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Applied Surface Science (v.258, #7)

Drop shaped zinc oxide quantum dots and their self-assembly into dendritic nanostructures: Liquid assisted pulsed laser ablation and characterizations by Subhash C. Singh; Ram Gopal (pp. 2211-2218).

.Display Omitted► Synthesis of drop shaped zinc oxide quantum dots and their self-assembly into novel and nice dendritic nanostructures. ► Mechanism of self-assembly based on the electrostatic attraction between the quantum dots has been manifested. ► Highly colloidal solution of drop shaped zinc oxide QDs with narrow size distribution has been reported. ► Dendritic assemblies are classifieds into three categories namely (i) linear axis with symmetrical branching, (ii) linear axis with asymmetrical branching, and (iii) curvilinear axis with asymmetrical branching. ► Ultraviolet to green broad photoluminescence is observed, which suggests its application as wide wavelength and white light source.Complex nanostructures and nano-assemblies have exhibited their potential application in the fabrication of future molecular machines and molecular devices. Liquid phase pulsed laser ablation is an easy, versatile, environmental friendly and rapidly growing method for the synthesis of nanostructured materials. Nanosecond pulsed laser ablation of zinc rod placed on the bottom of glass vessel containing methanol is used to produce colloidal solution of drop shaped zinc oxide quantum dots and their self-assembly into various dendritic nanostructures. UV–vis absorption, diffuse reflectance, transmission electron microscopy, and photoluminescence spectroscopy techniques are used for the optical, microscopic, structural and defect diagnosis of obtained colloidal quantum dots and their nano-assemblies. The average length, width and aspect ratio of drop shaped zinc oxide quantum dots are 6±2.4nm, 3.5±1.4nm and 1.69±0.4nm, respectively. Careful investigation of assemblies shows that most of them have linear growth, i.e. growth in longitudinal direction is higher as compared to the transverse direction with three types of classifications as (i) linear axis symmetrical branching, (ii) linear axis asymmetrical branching and (iii) curvilinear axis asymmetrical branching. Photoluminescence spectrum has emission peaks in UV, violet, blue and green spectral region corresponding to the excitonic and various defect related emissions.

Keywords: Laser ablation in liquid media; Liquid assisted laser processing; Semiconductor materials; Photoluminescence spectroscopy; Diffuse reflectance; Nanostructural evolution; Self-assembly; Drop shaped quantum dots; Dendritic nanostructures

The effects of carbon nanotube addition and oxyfluorination on the glucose-sensing capabilities of glucose oxidase-coated carbon fiber electrodes by Ji Sun Im; Jumi Yun; Jong Gu Kim; Tae-Sung Bae; Young-Seak Lee (pp. 2219-2225).

A high-performance glucose sensor was obtained with high sensitivity and rapid response time as a result of carbon nanotube addition, physical activation and surface modification.Display Omitted► High-performance glucose sensor by improved GOD immobilization. ► Efficient GOD immobilization by enlarged sites using physical activation. ► Rapid and high glucose-sensing ability by carbon nanotube additive. ► Improved interface affinity between GOD and sensing material by oxyfluorination.Glucose-sensing electrodes were constructed from carbon fibers by electrospinning and heat treatment. By controlling the pore size, the specific surface area and pore volume of the electrospun carbon fibers were increased for efficient immobilization of the glucose oxidase. Carbon nanotubes were embedded as an electrically conductive additive to improve the electrical property of the porous carbon fibers. In addition, the surface of the porous carbon fibers was modified with hydrophilic functional groups by direct oxyfluorination to increase the affinity between the hydrophobic carbon surface and the hydrophilic glucose oxidase molecules. The porosity of the carbon fibers was improved significantly with approximately 28- and 35-fold increases in the specific surface area and pore volume, respectively. The number of chemical bonds between carbon and oxygen were increased with higher oxygen content during oxyfluorination based on the X-ray photoelectron spectroscopy results. Glucose sensing was carried out by current voltagram and amperometric methods. A high-performance glucose sensor was obtained with high sensitivity and rapid response time as a result of carbon nanotube addition, physical activation and surface modification. The mechanism of the highly sensitive prepared glucose sensor was modeled by an enzyme kinetics study using the Michaelis–Menten equation.

Keywords: Glucose sensor; Carbon fiber; Oxyfluorination; Activation; Electrospinning

Structural stability of nano-sized crystals of HMX: A molecular dynamics simulation study by H. Akkbarzade; G.A. Parsafar; Y. Bayat (pp. 2226-2230).

► Molecular dynamics simulations of nanoparticles with 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 molecules of HMX are carried out at 300K. ► The intermolecular, intramolecular and total interaction energies per mole for the nanoparticles are calculated at 300K.► For the all sizes, the β-HMX is found to be more stable than α-HMX.► Also, α-HMX is more stable than δ-HMX. An increase in the sublimation enthalpy with the size of the nanoparticle can be seen.The interaction potential energy and heat of sublimation of nanoparticles of HMX crystal polymorphs are studied by using molecular dynamics methods with a previously developed force field [Bedrov, et al., J. Comput.-Aided Mol. Des. 8 (2001) 77]. Molecular dynamics simulations of nanoparticles with 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 molecules of HMX are carried out at 300K. The intermolecular, intramolecular and total interaction energies per mole for the nanoparticles are calculated at 300K. Then, we have calculated sublimation enthalpy of HMX crystal polymorphs with different sizes. For the all sizes, the β-HMX is found to be the most stable phase, due to having the least total interaction energy. Also, α-HMX is more stable than δ-HMX. An increase in the sublimation enthalpy with the size of the nanoparticle can be seen.

Keywords: Molecular-dynamics; HMX nanoparticle; Structural stability; Sublimation enthalpy

Layer-by-layer assembly and tribological property of multilayer ultrathin films constructed by modified graphene sheets and polyethyleneimine by Sheng Liu; Junfei Ou; Zhangpeng Li; Shengrong Yang; Jinqing Wang (pp. 2231-2236).

► A stable black dispersion of PSS-GS was obtained successfully. ► The graphene-based multilayer films were constructed by LBL assembly technique. ► The graphene-based films had high load affording ability and long anti-wear life.A series of graphene sheets (GS)-based multilayer films was constructed in virtue of layer-by-layer electrostatic self-assembly technique based on the negatively charged poly(sodium 4-styrenesulfonate) (PSS) mediated GS (PSS-GS) and the positively charged polyethyleneimine (PEI). High-resolution transmission electron microscope, atomic force microscope and micro-Raman spectrum characterizations demonstrated that the PSS-GS has been synthesized and could be assembled on the single-crystal silicon substrate. Ellipsometric thickness measurement and ultraviolet–visible absorption spectroscope confirmed the successive assemblies of GS. Finally, the macrotribological behaviors of different multilayer films were evaluated on a ball-on-plate macrotribometer and the results indicated that the prepared three- and five-layer films had high load affording ability and long anti-wear life, which could be highly dependent upon the high coverage and excellent self-lubricant properties that the GS owns intrinsically.

Keywords: Graphene sheets; Layer-by-layer self-assembly technique; Tribological property

Conductivity modification of ZnO film by low energy Fe¹⁰⁺ ion implantation by Ashutosh Kumar; J.B.M. Krishna; Dipankar Das; Sunita Keshri (pp. 2237-2245).

► The structural, optical and electrical behaviours have been studied for 300keV Fe¹⁰⁺ ion implanted ZnO films with fluence in the range 3×10¹⁵–1×10¹⁷. ► Implanted ZnO film (at ≤200K) shows p-type behaviour. ► Its magnetoresistance is positive in the temperature range 200–300K, but it becomes negative below 200K. ► In visible-infrared region the transmittance of the unimplanted sample is ∼90%, whereas that for implanted samples is in the range 82–89%. ► The photoluminescence spectrum are significantly intense for the implanted samples with fluence 1×10¹⁷ and 1×10¹⁶/cm³.In this paper we report the structural, optical and electrical behaviours of ZnO films implanted with 300keV Fe¹⁰⁺ ions. From UV–vis spectroscopy it is observed that the band gap of the films decreases after implantation. Photoluminescence yield seems to increase in the implanted samples. From Hall measurements it is observed that the unimplanted sample shows n-type conductivity for the entire temperature range (100–300K), whereas after implantation the samples show p-type conductivity for ≤200K. The DC resistivity of the implanted samples is found to be lower than that of the unimplanted sample. We have found that the magnetoresistance of our samples is positive in the temperature range 200–300K, but it becomes negative below 200K.

Keywords: Ion implantation; p–type ZnO; Photoluminescence; Hall measurement

Electroless silver plating on tetraethoxy silane-bridged fiber glass by Wan-Fu Lien; Po-Chen Huang; Shi-Chang Tseng; Chia-Hsiang Cheng; Shih-Ming Lai; Wen-Chang Liaw (pp. 2246-2254).

► The electroless silver plated FG with tetraethoxy silane modification was compared to that with no modification. ► The silane bridge provided more stability for binding with silver ions. ► The Ag coating on TEOS modified FG was more durable than that on the unmodified FG. ► The Ag coating on the TEOS modified FG has the lowest electrical resistance.Tetraethoxy silane was used to functionalize the surface of fiber glass (FG) for adsorption with the electroless plated silver shell. The performance of electroless silver plated FG with tetraethoxy silane modification was compared to that of unmodified FG in terms of mechanical and electrical properties. The silane bridge provided more stability for binding with different concentrations of electroless plating silver ions. The characterization was investigated by using field emission scanning electron microscope (FESEM), X-ray diffraction patterns (XRD), energy-dispersion X-ray (EDX), metal microscope (MM) and electric resistance. The Ag coating on TEOS modified FG was more durable than that of unmodified FG in the ball milling test, as confirmed by the data of electric resistance and residue weight. The optimized conditions for producing the Ag coating FG were also investigated. The Ag–Si–FG-3- c product in this study has the lowest electrical resistance of 1.56×10³Ω/cm² and good mechanical stability as exhibited in ball milling tests.

Keywords: Modified fiber glass; Electroless plating; Silane coupling agent; Tetraethoxy silane

Growth of epitaxially oriented Ag nanoislands on air-oxidized Si(111)-(7×7) surfaces: Influence of short-range order on the substrate by Anupam Roy; K. Bhattacharjee; J. Ghatak; B.N. Dev (pp. 2255-2265).

► A short-range order is observed on an oxidized Si(111)-(7×7) surface. ► The order is revealed by taking FFT of STM images. ► Ag deposition on this oxidized surface causes growth of Ag nanoislands. ► Crystallographic orientations of these Ag islands are like epitaxial Ag growth on Si(111). ► Apparently the short-range order on the oxide surface influences the orientation of the nanoislands.Clean Si(111)-(7×7) surfaces, followed by air-exposure, have been investigated by reflection high-energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). Fourier transforms (FTs) of STM images show the presence of short-range (7×7) order on the air-oxidized surface. Comparison with FTs of STM images from a clean Si(111)-(7×7) surface shows that only the 1/7th order spots are present on the air-oxidized surface. The oxide layer is ∼2–3nm thick, as revealed by cross-sectional transmission electron microscopy (XTEM). Growth of Ag islands on these air-oxidized Si(111)-(7×7) surfaces has been investigated by in situ RHEED and STM and ex situ XTEM and scanning electron microscopy. Ag deposition at room temperature leads to the growth of randomly oriented Ag islands while preferred orientation evolves when Ag is deposited at higher substrate temperatures. For deposition at 550°C face centered cubic Ag nanoislands grow with a predominant epitaxial orientation[11¯0]Ag||[11¯0]Si, (111)_Ag||(111)_Si along with its twin[1¯10]Ag||[11¯0]Si, (111)_Ag||(111)_Si, as observed for epitaxial growth of Ag on Si(111) surfaces. The twins are thus rotated by a 180° rotation of the Ag unit cell about the Si[111] axis. It is intriguing that Ag nanoislands follow an epitaxial relationship with the Si(111) substrate in spite of the presence of a 2–3nm thick oxide layer between Ag and Si. Apparently the short-range order on the oxide surface influences the crystallographic orientation of the Ag nanoislands.

Keywords: Ag islands on oxidized Si surfaces; Reflection high-energy electron diffraction; Scanning tunneling microscopy

Tailoring the wettability of nanocrystalline TiO₂ films by Qiyu Liang; Yan Chen; Yuzun Fan; Yong Hu; Yuedong Wu; Ziqiang Zhao; Qingbo Meng (pp. 2266-2269).

► The nanocrystalline TiO₂ based surface with controllable wettability was discussed. ► The fine surface TiO₂ films improved the hydrophobic and hydrophilic properties. ► The surface wettability can be easily tuned. ► The hydrophobic–hydrophilic patterns were used to area-selectively grow PS particles.The water contact angle (WCA) of nanocrystalline TiO₂ films was adjusted by fluoroalkylsilane (FAS) modification and photocatalytic lithography. FAS modification made the surface hydrophobic with the WCA up to ∼156°, while ultraviolet (UV) irradiation changed surface to hydrophilic with the WCA down to ∼0°. Both the hydrophobicity and hydrophilicity were enhanced by surface roughness. The wettability can be tailored by varying the concentration of FAS solution and soaking time, as well as the UV light intensity and irradiation time. Additionally, with the help of photomasks, hydrophobic–hydrophilic micropatterns can be fabricated and manifested via area-selective deposition of polystyrene particles.

Keywords: Nanocrystalline TiO; ₂; films; Photocatalytic lithography; Wettability control; Superhydrophobic; Superhydrophilic; Micropattern

Highly flexible transparent and conductive ZnS/Ag/ZnS multilayer films prepared by ion beam assisted deposition by Zhinong Yu; Jian Leng; Wei Xue; Ting Zhang; Yurong Jiang; Jie Zhang; Dongpu Zhang (pp. 2270-2274).

ZnS/Ag/ZnS (ZAZ) multilayer films were prepared on polyethene terephthalate (PET) by ion beam assisted deposition at room temperature. The structural, optical and electrical characteristics of ZAZ multilayers dependent on the thickness of silver layer were investigated. The ZAZ multilayers exhibit a low sheet resistance of about 10Ω/sq., a high transmittance of 92.1%, and the improved resistance stabilities when subjected to bending. When the inserted Ag thickness is over 12nm, the ZAZ multilayers show good resistance stabilities due to the existence of a ductile Ag metal layer. The results suggest that ZAZ film has better optoelectrical and anti-deflection characteristics than conventional indium tin oxide (ITO) single layer.

Keywords: Transparent and conductive film; Zinc sulfide (ZnS); Ion beam assisted deposition (IBAD); Optical properties; Sheet resistance

Development of rf plasma sputtered Al₂O₃–TiO₂ multilayer broad band antireflecting coatings and its correlation with plasma parameters by P. Laha; A.B. Panda; S.K. Mahapatra; P.K. Barhai; A.K. Das; I. Banerjee (pp. 2275-2282).

TiO₂/Al₂O₃/TiO₂/Al₂O₃ multilayer structures were obtained at different oxygen:argon gas ratios of 20:80, 30:70, 50:50 and 60:40sccm and constant rf power of 200W using reactive magnetron sputtering. Grain size and elemental distribution in the films were studied from AFM image and XPS spectra respectively. The deposited grain size increased with increasing oxygen:argon gas ratio. The optical band gap, refractive index, extinction coefficient were calculated from UV–vis transmittance and reflectance spectra. It was observed that the value of refractive index, extinction coefficient and band gap increased with increasing oxygen. These variations are due to the defects levels generated by the heterostructure and explained by the PL spectrum. The antireflecting (AR) efficiency of the films was estimated from the reflectance spectra of the films. Broad band antireflecting coating for the visible range was achieved by varying oxygen content in the film. The plasma chemistry controlled the antireflecting property by the interface interdiffusion of atoms during layer transition in multilayer deposition. The in situ investigation of the plasma chemistry was performed using optical emission spectroscopy. The plasma parameters were estimated and correlated with the characteristics of the films.

Keywords: Al; ₂; O; ₃; TiO; ₂; X-ray photoemission spectroscopy (XPS); PL; Optical properties; OES

Influence of mesoporous substrate morphology on the structural, optical and electrical properties of RF sputtered ZnO layer deposited over porous silicon nanostructure by Yogesh Kumar; J. Escorcia Garcia; Fouran Singh; S.F. Olive-Méndez; V.V. Sivakumar; D. Kanjilal; V. Agarwal (pp. 2283-2288).

► Morphology and grain size of ZnO crystallites depends strongly on the morphology/pore size of mesoporous Si substrates. ► Controllable morphological features of ZnO could be used to control the optical and transport properties. ► Such substrates can be also be used to amplify or change the sensing response of thin zinc oxide films.Morphological, optical and transport characteristics of the RF sputtered zinc oxide (ZnO) thin films over the mesoporous silicon (PS) substrates have been studied. Effect of substrate porosity on the grain growth and transport properties of ZnO has been analyzed. Physical and optical properties of ZnO–PS structures were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), and photoluminescence (PL) spectroscopy. Our experimental results indicate that on changing porosity of the PS substrates, regularity of the spatial distribution of the ZnO nanocrystallites can be controlled. While the morphology and grain size of ZnO depended strongly on the morphology and pore size of the PS substrates, the rectifying factors of the metal semiconductor junction were found to be different by a factor of 3. The deposition of semiconducting oxides on such mesoporous substrates/templates offers the possibility to control their properties and amplify their sensing response.

Keywords: Zinc oxide; Porous silicon; RF sputtering; Mesoporous templates; Optical properties; Transport; Morphology

Laser assisted embedding of nanoparticles into metallic materials by Dong Lin; Sergey Suslov; Chang Ye; Yiliang Liao; C. Richard Liu; Gary J. Cheng (pp. 2289-2296).

► Half-embedding nanoparticles with diameter less than 100nm into metallic materials. ► Large area and uniform distribution of half-embedded nanoparticles are achieved using a pulsed laser irradiation to induce substrate melting. ► This process works for both transparent and opaque nanoparticles ► Various types of surface properties of metallic materials can be introduced by these half-embedded nanoparticles.This paper reports a methodology of half-embedding nanoparticles into metallic materials. Transparent and opaque nanoparticles are chosen to demonstrate the process of laser assisted nanoparticle embedding. Dip coating method is used to coat transparent or opaque nanoparticle on the surface of metallic material. Nanoparticles are embedded into substrate by laser irradiation. In this study, the mechanism and process of nanoparticle embedding are investigated. It is found both transparent and opaque nanoparticles embedding are with high densities and good uniformities.

Keywords: Embedding; Laser processing; Simulation; Nanoparticles; Surface functionization

Morphological transition of ZnO nanostructures influenced by magnesium doping by T. Premkumar; Y.S. Zhou; Y. Gao; K. Baskar; L. Jiang; Y.F. Lu (pp. 2297-2300).

Wurtzite zinc oxide (ZnO) nanochains have been synthesized through high-pressure pulsed laser deposition. The chain-like ZnO nanostructures were obtained from magnesium (Mg) doped ZnO targets, whereas vertically aligned nanorods were obtained from primitive ZnO targets. The Mg doping has influenced the morphological transition of ZnO nanostructures from nanorods to nanochains. The field emission scanning electron microscope images revealed the growth of beaded ZnO nanochains. The ZnO nanochains of different diameters 40 and 120nm were obtained. The corresponding micro-Raman spectra showed strong E_2H mode of ZnO, which confirmed the good crystallinity of the nanochains. In addition to near band edge emission at 3.28eV, ZnO nanochains show broad deep level emission at 2.42eV than that of ZnO nanorods.

Keywords: ZnO nanochains; ZnO nanorods; FESEM; Micro-Raman spectroscopy; HPPLD

In vitro biocompatibility study of electrospun copolymer ethylene carbonate-ɛ-caprolactone and vascular endothelial growth factor blended nanofibrous scaffolds by Xiangman Zhang; Zhengyu Shi; Weiguo Fu; Zhenjie Liu; Zhengdong Fang; Weifeng Lu; Yuqi Wang; Feng Chen (pp. 2301-2306).

► In this study, we synthesized a biodegradable polymer (poly(ethylene carbonate-ɛ-caprolactone) (poly(EC-CL)), and co-electrospun with vascular endothelial growth factor (VEGF) to construct a drug-released nano-scaffolds. ► Our results show that VEGF/poly(EC-CL) blended scaffolds provided good support for endothelial cell growth over the percentages 10ng/g (VEGF/poly(EC-CL)). ► Our work shows that poly(EC-CL) co-electrospun with VEGF has a great potential for vascular engineering application in the future.Electrospun blended nanofibrous scaffolds were fabricated from an synthetic biodegradable polymer (poly(ethylene carbonate-ɛ-caprolactone) (poly(EC-CL)) and vascular endothelial growth factor with different weight ratios. Results showed that the diameter of blended scaffolds was 440±55nm. VEGF on the surface of the blended scaffolds was identified by immunofluorescence. In vitro cell proliferation, viability assay results showed that human umbilical vein endothelial cells (HUVECs) had a good growth and spread morphology on the blended scaffolds. Scaffolds electrospun from this polymer contained VEGF had a good application in tissue engineering.

Keywords: Electrospinning; Vascular endothelial growth factor

Enhanced photoelectrochemical performance of Ti-doped hematite thin films prepared by the sol–gel method by Xiaojuan Lian; Xin Yang; Shangjun Liu; Ying Xu; Chunping Jiang; Jinwei Chen; Ruilin Wang (pp. 2307-2311).

► We synthesize pure and Ti-doped hematite films by the sol–gel route. ► Worm-like nano particles are prepared. ► The IPCE increases to 32.6% without any bias vs. SCE at 400nm. ► Ti⁴⁺ ions promote the separation of electrons and holes.Ti-doped α-Fe₂O₃ thin films were successfully prepared on FTO substrates by the sol–gel route. Hematite film was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). The XRD data showed α-Fe₂O₃ had a preferred (110) orientation which belonged to the rhombohedral system. Interestingly, the grains turned into worm-like shape after annealed at high temperature. The IPCE could reach 32.6% at 400nm without any additional potential vs. SCE. Titanium in the lattice can affect the photo electro chemical performance positively by increasing the conductivity of the thin film. So the excited electrons and holes could live longer, rather than recombining with each other rapidly as undoped hematite. And the efficient carrier density on the Ti-doped anode surface was higher than the undoped anode, which contribute to the well PEC performance.

Keywords: Hematite; Thin films; Ti-doped; Sol–gel; IPCE; Water splitting

Synthesis and properties of side-chain-type ion exchange membrane PEEK-g-StSO₃Na for bipolar membranes by Xuehong Huang; Dengbin Huang; Xiaojuan Ou; Fuchuan Ding; Zhen Chen (pp. 2312-2318).

. Side-chain-type ion exchange membranes (PEEK-g-StSO₃Na) were prepared by grafting poly(ether ether ketone) containing propenyl groups with sodium sulfonic styrenet (StSO₃Na), and use KH-570 as cross-linkable group. PEEK-g-StSO₃Na has clear microphase-separated structure composed of hydrophilic domains and hydrophobic moieties.Display Omitted► Side-chain-type ion exchange membranes (PEEK-g-StSO₃Na) were prepared by grafting poly(ether ether ketone) containing propenyl groups with sodium sulfonic styrene (StSO₃Na), employing KH-570 as cross-linkable group. ► The ion exchange capacities (IECs) of the membranes ranged from 2.27 to 2.50mmolg⁻¹. ► They displayed reasonably high H⁺ permeability and low AC impedance.Side-chain-type ion exchange membranes (PEEK-g-StSO₃Na) were prepared by grafting poly (ether ether ketone) (PEEK) containing propenyl groups with sodium sulfonic styrene (StSO₃Na) and KH570. PEEK was synthesized by the aromatic nucleophilic polycondensation reaction of 4,4′-difluorobenzophenone, bisphenol A and diallylbisphenol A. The synthesized copolymers with the –SO₃Na group on the side chain of polymers possessed high molecular weights. The cross-linking reaction was carried out through a sol–gel reaction of the trimethoxysilane group. The copolymer membranes exhibited excellent mechanical properties due to their aromatic structure extending through the backbone and flexible StSO₃Na aliphatic chains. The ion exchange capacities (IECs) of the membranes ranged from 2.27 to 2.50mmolg⁻¹ and the water content ranged from 107.2 to 126.1%, with both parameters increasing with StSO₃Na grafting degree. The H⁺ permeability of copolymer membranes increased with increasing IEC, reaching value above 0.3056mol/L at 2h, which is higher than that of Nafion^® 117 at the same measurement condition. They displayed reasonably high H⁺ permeability due to the higher acidity of benzoyl sulfonic acid group, the larger interchain spacing, which is available for water occupation, and the lower AC impedance of the bipolar membrane.

Keywords: Poly (ether ether ketone); Graft polymerization; Cation exchange membrane; Side-chain-type

Porous ceramic membrane with superhydrophobic and superoleophilic surface for reclaiming oil from oily water by Changhong Su; Youqian Xu; Wei Zhang; Yang Liu; Jun Li (pp. 2319-2323).

Porous ceramic membrane with superhydrophobic and superoleophilic surface used to reclaiming oily from oily water containing clay particles.Display Omitted► Porous ceramic membrane with superhydrophobic and superoleophilic inner surface has been fabricated via sol-gel method and then surface modification with a low surface energy coating. ► An oil- water separator based on the membrane can reclaim directly oil from oily water or even from oily water containing clay particles. ► The Separation efficiency and velocity depend on oil content of oily water and whether contains clay particles.A porous ceramic tube with superhydrophobic and superoleophilic surface was fabricated by sol-gel and then surface modification with polyurethane-polydimethysiloxane, and an oil-water separator based on the porous ceramic tube was erected to characterize superhydrophobic and superoleophilic surface's separation efficiency and velocity when being used to reclaim oil from oily water and complex oily water containing clay particle. The separator is fit for reclaiming oil from oily water.

Keywords: Porous ceramic membrane; Superhydrophobic, Superoleophilic, Oil-water separation

Study of temperature effects on the conduction and trapping of charges in the alkali-silicate glass under electron beam irradiation by S. Fakhfakh; B. Elsafi; Z. Fakhfakh; O. Jbara (pp. 2324-2331).

► Temperature effects on the charging behaviour of alkali-silicate glasses. ► Currents measurements obtained by the EIM using a setup adapted to the SEM. ► Charging ability of glasses decreases with increasing temperature. ► The higher is the temperature and the lower is the SEE yield.A scanning electron microscope (SEM) is employed to investigate the temperature effect on the charging behaviour of alkali-silicate glasses under electron beam irradiation using electrostatic influence method (EIM). A modified special arrangement adapted to the SEM allows to study charging mechanisms and charge transport characteristics of these glasses using the simultaneous measurement of displacement and leakage currents. The trapping process during continuous electron irradiation can be directly determined by the EIM. The experimental results reveal that the charging ability of glasses decreases with increasing temperature. The variation of charge process has been confirmed by measuring the surface potential in response to the sample temperature. In this report, we introduce also the secondary electron emission (SEE) yield. It was found the strong dependence of the SEE yield on the temperature variation. The higher is the temperature and the lower is the SEE yield. The trapping ability is analyzed taking into account the regulation mechanisms involved under electron irradiation.

Keywords: PACS; 61.80. Fe; 61.82 Ms; 68.49 JkSEM; Glasses; Charge effect; Temperature

Influence of He/O₂ atmospheric pressure plasma jet treatment on subsequent wet desizing of polyacrylate on PET fabrics by Xuming Li; Jun Lin; Yiping Qiu (pp. 2332-2338).

► Plasma as a pre-treatment for NaHCO₃ desizing of polyacrylate size on PET fabric. ► The change of surface morphology and surface chemical composition of polyacrylate treated by plasma were studied. ► Influence of plasma etching on weight loss of polyacrylate. ► Compare with control sized fabric, plasma pre-treatment can markedly facilitate NaHCO₃ desizing efficiency.The influence of He/O₂ atmospheric pressure plasma jet (APPJ) treatment on subsequent wet desizing of polyacrylate on PET fabrics was studied in the present paper. Weight loss results indicated that the weight loss increased with an increase of plasma treatment time. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) showed an increased surface roughness after the plasma treatment. SEM also showed that the fiber surfaces were as clean as unsized fibers after 35s treatment followed by NaHCO₃ desizing. X-ray photoelectron spectroscopy (XPS) analysis indicated that oxygen-based functional groups increased for the plasma treated polyacrylate sized fabrics. The percent desizing ratio (PDR) results showed that more than 99% PDR was achieved after 65s plasma treatment followed by a 5min NaHCO₃ desizing. Compared to conventional wet desizing, indicating that plasma treatment could significantly reduce desizing time.

Keywords: Atmospheric pressure plasma jet; Polyacrylate; Desizing; PET fabrics; AFM; XPS; SEM

Micro-punching process based on spallation delamination induced by laser driven-flyer by Jianke Di; Ming Zhou; Jian Li; Chen Li; Wei Zhang; George Amoako (pp. 2339-2343).

► We propose a micro-punching process for microstructure on films. ► This method is based on spallation delamination induced by laser driven-flyer. ► We examine this method for Au film on glass substrates and polyimide substrate. ► The spatial resolution of microstructure by this method is able to reach micron level.In this article, we proposed a micro-punching process for microstructure on films based on laser driven-flyer induced spallation delamination phenomenon at the interface between a film and its substrate. To validate such a micro-punching process, a series of experiments were carried out for fabrication of microstructures on Au films coated on K9 glass substrates and polyimide substrate. Results show that through such a punching process, the microstructure on Au films can be fabricated efficiently and the spatial resolution is able to reach micron level. Moreover, we found that this method was more suitable for films coated on soft substrates rather than that coated on brittle substrates due to the additional destruction of the brittle substrate. This micro-punching process has a wide range of potential application in microfluidic devices, biodevices and other MEMS devices.

Keywords: Micro-punching process; Spallation delamination; Laser driven-flyer; Microfabrication

Surface modification of poly(styrene-b-(ethylene-co-butylene)-b-styrene) elastomer via photo-initiated graft polymerization of poly(ethylene glycol) by Xiaomeng Li; Shifang Luan; Huawei Yang; Hengchong Shi; Jie Zhao; Jing Jin; Jinghua Yin; Paola Stagnaro (pp. 2344-2349).

► Saturated medical SBC was subjected to graft polymerization for the first time. ► The PEGMA-modified SEBS had a water contact angle of about 60°. ► Protein adsorption was reduced by 55% after PEGMA grafted on the SEBS. ► Platelet adhesion of SEBS was greatly improved by graft polymerization of PEGMA.Poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) copolymer biomedical elastomer was covalently grafted with poly(ethylene glycol) methyl ether methacrylate (PEGMA) via a photo-initiated graft polymerization technique. The surface graft polymerization of SEBS with PEGMA was verified by ATR–FTIR and XPS. Effect of graft polymerization parameters, i.e., monomer concentration, UV irradiation time and initiator concentration on the grafting density was investigated. Comparing with the virgin SEBS film, the PEGMA-modified SEBS film presented an enhanced wettability and a larger surface energy. Besides, the surface grafting of PEGMA imparted excellent anti-platelet adhesion and anti-protein adsorption to the SEBS surface.

Keywords: Poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) copolymer; Photo-initiated graft polymerization; Poly(ethylene glycol) methyl ether methacrylate (PEGMA); Wettability; Hemocompatibility

Microtribological study of perfluoropolyether with different functional groups coated on hydrogen terminated Si by Myo Minn; Nalam Satyanarayana; Sujeet K. Sinha; Hirofumi Kondo (pp. 2350-2355).

► Influence of hydrogen termination of the Si substrate on the tribological properties of PFPE films. ► H-termination of the Si surface prior to PFPE coating has increased the wear durability by several orders when compared to PFPE coating onto untreated Si. ► H-termination on Si is a simple and cost-effective means to modify the tribological properties of Si.Friction and wear properties of different perfluoropolyether (PFPE) films with and without hydrogen termination on Si (Si–H) were studied using a ball-on-disk tribometer. The physical and chemical properties of the films were evaluated using contact angle measurement, atomic force microscopy and X-ray photoelectron spectroscopy. Coating of PFPEs onto bare Si has lowered the coefficient of friction (from 0.6 for Si to ∼0.05 with PFPE) and enhanced the wear durability (20,000 times) in comparison with those for bare Si which failed immediately. The introduction of hydrogen termination onto Si prior to PFPE coating has further increased the wear durability of PFPE with different functional groups several times (>5 times) under a normal load of 30mN and a sliding speed of 0.052m/s.

Keywords: Hydrogen-termination; Tribology; PFPE

Interactions of ferrimagnetic glass/glass-ceramics with bovine serum albumin by K. Sharma; S. Bhattacharya; C. Murali; K.G. Bhushan; G.P. Kothiyal (pp. 2356-2361).

► Structural and surface properties of glassy materials 34 SiO₂–(45−x) CaO–16 P₂O₅–4.5 MgO–0.5 CaF₂–x Fe₂O₃ (x=10, 15, 20wt%) are studied. ► Iron oxide behaves as a structural modifier in the glass compositions. ► Surface properties are modified with addition of iron oxide. ► The better response in BSA was observed when iron oxide content was increased.Glasses/glass-ceramics with nominal composition 34 SiO₂–(45− x)CaO–16P₂O₅–4.5MgO–0.5CaF₂− xFe₂O₃ (where x=10, 15, 20wt%) have been prepared by melt quenching technique. These are characterized for structural and micro structural properties by using XRD and Raman spectroscopy. Interaction of glass-ceramics samples with bovine serum albumin (BSA) has been studied using SEM and TOF-SIMS. The formation of magnetite, apatite and wollastonite phases are observed. Typical sizes of crystallites as seen from SEM measurement are 30–50nm. The progressive addition of iron oxide to glass leads to increase in number of non-bridging oxygen, which in turn affects the response of glass-ceramics when immersed in BSA. The samples with 15 and 20wt% Fe₂O₃ have shown nearly full surface coverage with BSA, while the sample with 10wt% Fe₂O₃ shows poor adhesion.

Keywords: Glass; Glass-ceramics; SEM; XRD

Effect of surface film on sliding friction and wear of copper-impregnated metallized carbon against a Cu–Cr–Zr alloy by Y.A. Wang; J.X. Li; Y. Yan; L.J. Qiao (pp. 2362-2367).

► The composition of surface films are different under the condition of with and without electrical current. ► Oxide layer plays the key role in reducing friction coefficient. ► The lubricating performance of surface film is different under different electrical current.A block-on-ring wear test was performed between a copper-impregnated metallized carbon brush and a Cu–Cr–Zr alloy ring under ambient environment. After 50km of rubbing at 20A electrical current and 111kPa normal pressure at a constant velocity of 25km/h, a surface film, which was composed of Cu₂O, CuO, C and water, formed on the copper alloy ring due to graphite transfer from the brush to the copper alloy and oxidation of the copper. A second series of friction and wear tests was carried out both with and without this initial surface film and at different electrical currents. The friction coefficient and wear mass loss were compared. The results showed that the initial surface film could reduce the friction coefficient in the presence of an electrical current, but in the absence of an electrical current, the film's lubricating performance gradually degraded as the test progressed. Wear mass losses caused by the rubbing of the brushes against the rings having an initial surface film were lower when the electrical currents were 0A, 10A and 15A, respectively, while the situation was reversed when the electrical current was 20A, i.e., the wear mass loss of the brush specimen rubbing against a ring with an initial surface film was higher than that of a ring without it.

Keywords: Oxide layer; Electrical contacts; Friction; Wear

Depositing nanoparticles inside millimeter-size hollow tubing by Alexandra Friedman; Nina Perkas; Yuri Koltypin; Aharon Gedanken (pp. 2368-2372).

The picture demonstrates the ability to coat the inner walls of these tubings.Display Omitted► Evidence for the ability to deposit silver nanoparticles onto the inner side of hollow tubing is provided. ► The coating is done sonochemically. ► The inner surface was coated with a larger amount of nanoparticles than the outer surface. ► The same results were obtained on PVC, rubber, and Teflon tubing.The inner and the outer walls of hollow tubing with an inner diameter of 0.4–0.9cm and an outer diameter of 0.6–1.3cm were coated with silver nanoparticles (NPs) by a one-step process using ultrasound irradiation. The structure and morphology of the nanoparticles (NPs) inside the hollow tubing and on the outer surface were characterized using methods such as XRD, TEM, HR-TEM, and HRSEM. The inner surface of the tubing was found to be coated with more silver than the outer surface. The coating was done on tubing made of rubber, PVC, Teflon and polyethylene. Sonochemistry is demonstrated as a method for depositing nanoparticles on the inner wall of a tube.

Keywords: Sonochemistry; Nanoparticles; Coatings; Tubing

Photo-induced growth of silver nanoparticles using UV sensitivity of cellulose fibers by A. Alahgholipour Omrani; N. Taghavinia (pp. 2373-2377).

► Here we use UV irradiation to make the surface of cellulose fibers reductive. ► This situation provides a self-limiting condition to form stable silver nanoparticles. ► It was shown that the determining parameter is UV intensity rather than Ag⁺ concentration. ► Grown silver nanoparticles on the cellulose surface are recognized by XPS, SEM and DRS.A simple method has been demonstrated to grow silver nanoparticles on the surface of cellulose fibers. The preparation is based on photo-activation of surface by ultraviolet (UV) photons, followed by chemical reduction of silver nitrate. It is found that the concentration of silver nitrate in the solution is not a determining factor, while UV intensity affects the rate of initial growth and determines the final concentration of the loaded silver. We explain the phenomena based on a model including the number of reducing sites on the surface of cellulose fibers activated by UV photons, and a release mechanism that causes a slow rate of dissolution of silver back into the solution.

Keywords: Silver; Nanoparticles; UV irradiation; Cellulose

Wetting mode transition of nanoliter scale water droplets during evaporation on superhydrophobic surfaces with random roughness structure by Tsutomu Furuta; Toshihiro Isobe; Munetoshi Sakai; Sachiko Matsushita; Akira Nakajima (pp. 2378-2383).

Display Omitted► Small droplets were evaporated on superhydrophobic coatings with random roughness. ► The wetting mode transition was confirmed on the coatings. ► The calculated values of mode transition radii were close to the experimental values.During evaporation, shape changes of nanoliter-scale (80–100nL) water droplets were evaluated on two superhydrophobic surfaces with different random roughness (nm-coating, μm-coating). The square of the contact radius and the square of the droplet height decreased linearly with evaporation time. However, trend changes were observed at around 170s (nm-coating) and around 150s (μm-coating) suggesting a wetting mode transition. The calculated droplet radii for the wetting mode transition from the average roughness distance and the average roughness height of these surface structures were approximately equal to the experimental values at these trend changes. A certain level of correlation between the roughness size and droplet radius at the wetting mode transition was confirmed on surfaces with random roughness.

Keywords: Superhydrophobic; Wetting mode transition; Contact angle; Surface roughness

Theoretical study of breaking and slipping processes for HMX/graphite interface by Y. Long; Y.G. Liu; F.D. Nie; J. Chen (pp. 2384-2392).

► We study breaking and slipping processes of HMX/graphite interface. ► Three kinds of interfaces are investigated: normal, step and hollow. ► We find different defects play different roles in interface processes. ► And different interface processes have different energy dissipation ways.Interface dynamics is an important issue to understand the hot spot formation mechanism in high energy explosives. We have studied the interface between octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and graphite. The former is a good performance explosive but has high sensitivity. The latter is the desensitizer for the former. Two kinds of dynamic processes have been investigated: breaking and slipping. The structure evolution, energy variation, and breaking/slipping stresses were calculated. We found that different interface processes lead to different energy dissipation ways. For breaking, it is by surface relaxation. For slipping, it is by interface friction. Both the two ways contribute to the hot spot formation and shock sensitivity of explosives.

Keywords: PACS; 68.35.bm; 68.55.am; 68.60.BsMolecular dynamics; Linear response method; Energy dissipation; Interface friction

Synthesis of TiO₂ rutile nanoparticles by PLA in solution by V. Caratto; M. Ferretti; L. Setti (pp. 2393-2396).

This paper describes the synthesis of TiO₂ nanoparticles by laser ablation in solution synthesis (Lasis). The laser excimer beam passes through a focusing lens and it is sent to the reaction chamber. The frequency used during the synthesis was 20Hz, intensity 26kV The metal ablated by the laser beam undergoes an oxidation process resulting from the reaction with water. We obtain TiO₂ nanoparticles with average size of 6.5nm, crystallized in the rutile structure. The crystallographic and morphological structure was studied by transmission electron microscopy.

Keywords: TiO; ₂; Rutile; Lasis; Nanoparticle

Modification of laser induced damage threshold of ZrO₂ thin films by using time–temperature gradient annealing by Alireza Bananej; Amir Hassanpour (pp. 2397-2403).

► In this study we consider the effect of time–temperature gradient annealing, TTGA, on laser induced damage threshold. ► ZrO₂ optical coatings is one of the best candidate of optical films. ► Optical, thermal and mechanical improved by TTGA. ► Significant enhancement of LIDT via TTGA.As a result of using time–temperature gradient annealing, the structural and optical properties and hence, thermal properties of ZrO₂ thin films deposited by electron gun, enhanced considerably compared with rapid thermal annealing. Also, it can be seen time- temperature gradient annealing caused to decrease the total stress and number of thermal barrier along the film. Therefore, according to our experimental results, which is agree with theoretical analysis, the laser induced damage threshold of ZrO₂ films can be enhanced significantly compared with rapid annealing procedure.

Keywords: Thin films; Laser induced damage threshold; Grain size; Stress; Time–temperature gradient annealing

Surface modification of magnesium aluminum hydroxide nanoparticles with poly(methyl methacrylate) via one-pot in situ polymerization by Xiaojun Guo; Leihua Zhao; Li Zhang; Jing Li (pp. 2404-2409).

Display Omitted► DN-27 is applied to the surface modification of MAH nanoparticles by grinding method. ► Hydrophobic PMMA-MAH particles are obtained by a simple one-pot in situ polymerization reaction. ► The thermal stability of the PMMA-MAH composite particles had been improved. ► The sample obtained possesses a higher water contact angle of 108°.Hydrophobic magnesium aluminum hydroxide composite particles (PMMA-MAH) were obtained by means of grafting poly(methyl methacrylate) (PMMA) onto the surface of magnesium aluminum hydroxide(MAH) nanoparticles after a novel type of phosphate coupling agent (DN-27) modification. The introduction of functional double bonds was firstly conducted on the surface of nanoparticles by DN-27 modification, followed by one-pot in situ polymerization on the particles surface using methyl methacrylate (MMA) as monomer, azoisobutyronitrile (AIBN) as initiator and sodium dodecyl sulfate (SDS) as stabilizer to graft PMMA on the surface of DN-27-modified MAH particles. The obtained composite particles were characterized by field-emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD). The results show that the organic macromolecule PMMA could be successfully grafted on the surface of DN-27-modified MAH nanoparticles and the thermal stability of the PMMA-MAH composite particles had been improved. Compared with unmodified blank MAH sample, the product obtained with this method possesses better hydrophobic properties such as a higher water contact angle of 108° and a well dispersion.

Keywords: PMMA grafting; Magnesium aluminum hydroxide; Phosphate coupling agent; Modification; Hydrophobic property

N-containing carbons from styrene–divinylbenzene copolymer by urea treatment by Sergey V. Zhuravsky; Mykola T. Kartel; Yuriy O. Tarasenko; Silvia Villar-Rodil; Gábor Dobos; Ajna Tóth; Juan M.D. Tascón; Krisztina László (pp. 2410-2415).

► N-containing synthetic carbons were prepared in a cost-effective way. ► The final product has a surface area of 1135m²/g. ► Ca 70% of the pore volume comes from micropores with an average width of 0.7nm. ► Surface nitrogen content is 2.3at.%, 44% of which is quaternary nitrogen.N-containing synthetic carbons with narrow porosity were prepared from a chlorinated styrene and divinylbenzene copolymer by a multistep method with a yield of 34wt%. Surface chemical treatment and thermal carbonization of the starting copolymer was monitored by urea impregnation. Steam activation, oxidation and an additional heat treatment gave the final product. The synthesis route was designed in a cost-effective way. The porosity and the concentration of the introduced nitrogen atoms were determined at each step. The final product has a surface area of 1135m²/g. More than 70% of the pore volume comes from micropores with an average width of 0.7nm. The 2.3at.% surface nitrogen atoms are distributed among five detectable species, of which about 44% is quaternary nitrogen.

Keywords: Nanoporous carbon; Surface chemistry; Surface N-group; Pore structure; XPS

Preparation of ceramic coating on Ti substrate by plasma electrolytic oxidation in different electrolytes and evaluation of its corrosion resistance: Part II by M. Shokouhfar; C. Dehghanian; M. Montazeri; A. Baradaran (pp. 2416-2423).

► Formation of ceramic PEO coating on Titanium surface improves its properties. ► Effect of electrolyte composition on PEO coated samples was investigated. ► Coatings with different surface morphologies and thicknesses were obtained. ► The phase composition of coatings was different and had different amount of rutile and anatase phases. ► Coated samples showed better corrosion behavior than bare titanium.The aim of this work is to discuss the growth characteristics and corrosion behavior of the prepared ceramic coatings on titanium by plasma electrolytic oxidation (PEO) technique in different electrolytes. PEO process was carried out on titanium under constant voltage regime using a pulse power supply. Three kinds of electrolytes, phosphate, silicate and borate based solutions, were used to evaluate the influence of electrolyte composition on the structure, surface morphology, phase composition and corrosion behavior of prepared ceramic oxide films (titania). The phase composition of the coatings was investigated by X-ray diffraction. Scanning electron microscopy was employed to evaluate the growth and surface morphology of coatings. Elements of coatings were investigated with energy dispersive spectrometer. Corrosion behavior of the coatings was also examined by potentiodynamic polarization and electrochemical impedance spectroscopy. The spark voltage of oxide films had a significant effect on the surface morphology, size and homogeneity of micro-pores, thickness and corrosion properties of coatings.

Keywords: Titanium; Plasma electrolytic oxidation; Ceramic coatings; Growth characteristics; Corrosion behavior

Plasma modification of polypropylene surfaces and its alloying with styrene in situ by Gui-qiu Ma; Ben Liu; Chen Li; Dinghai Huang; Jing Sheng (pp. 2424-2432).

Display Omitted► Plasma processing can etch the surface of polymer and produce active free radical. ► The active free radical can induce monomer grafting polymerization without initiator and catalysts. ► The homopolymer of styrene can be formed under grafting copolymerization of styrene onto polypropylene, it follows that the alloying of polypropylene with styrene is achieved in situ.The treatment of polypropylene surfaces has been studied by dielectric barrier discharges plasma of Ar. The structure and morphology of polypropylene surfaces of Ar plasma modification are characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectrometers and scanning electron microscope. The modified by plasma treatment of iPP (isotactic polypropylene) surface properties have been examined in a determination of free radicals. The modified active surfaces of polypropylene can induce grafting copolymerization of styrene onto polypropylene. The structure of grafting copolymer is characterized and the grafting percent of styrene onto polypropylene is calculated. The homopolymer of styrene can be formed under grafting copolymerization of styrene onto polypropylene, which follows that the alloying of polypropylene with styrene is achieved in situ.

Keywords: Polymer surface; Plasma modification; Grafting copolymerization

Tribological properties of Ti-doped DLC coatings under ionic liquids lubricated conditions by Xin Feng; Yanqiu Xia (pp. 2433-2438).

► Ti-DLC coatings on AISI 52100 steel have a very fine structure. ► Ionic liquids reduce the friction and wear of Ti-DLC coatings. ► Ionic liquids are superior to PFPE under Ti-DLC coatings against steel conditions. ► Tribochemical films and chemical adsorption films were formed on the worn surface.In this paper, titanium doped diamond-like carbon (Ti-DLC) coatings were prepared onto AISI 52100 steel substrates using medium frequency magnetic sputtering process, and were analyzed using the Raman and transmission electron microscope (TEM). Two kinds of 1,3-dialkyl imidazolium ionic liquids (ILs) were synthesized and evaluated as lubricants for Ti-DLC/steel contacts at room temperature, and PFPE as comparison lubricant. The tribological properties of the ILs were investigated using a ball-on-disk type UMT reciprocating friction tester. The results indicated that the ILs have excellent friction-reducing properties, the friction coefficient kept at a relatively stable value of 0.07–0.06, which was reduced approximately by 47% compared with perfluoropolyether (PFPE). The worn surfaces of Ti-DLC coatings were observed and analyzed using a MICROXAM-3D non-contact surface profiler, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The Ti-DLC coatings using ionic liquids lubricating systems are considered as potential lubricating system in vacuum and space moving friction pairs.

Keywords: Ti-DLC coatings; Ionic liquids; Boundary lubrication; Friction coefficient

The effect of carbon nanotubes on the corrosion and tribological behavior of electroless Ni–P–CNT composite coating by Mostafa Alishahi; Seyed Mahmoud Monirvaghefi; Ahmad Saatchi; Seyed Mehdi Hosseini (pp. 2439-2446).

► CNTs lead to an increase in nanocrystalline phase's fraction of Ni-P-CNT coating. ► CNTs increase hardness of both as-deposited and heat treated coatings. ► CNTs significantly improve tribological behavior of composite coating. ► Ni-P-CNT composite coating exhibit better corrosion behavior than Ni-P coating. ► CNTs could accelerate the chemical passivation of the Ni–P–CNT composite coating.In this study, Ni–P–CNT composite coating was successfully deposited on the surface of copper by electroless plating. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were used to characterize the coatings. The wear behavior of the coatings was investigated using a pin-on-disk test rig and subsequently friction coefficient data were reported. The corrosion behavior of the Ni–P and Ni–P–CNT coated specimen were evaluated through polarization curves and electrochemical impedance spectroscopy (EIS) in 3.5wt.% NaCl aqueous solution at the room temperature. The results indicated that the incorporation of carbon nanotubes (CNTs) in the coating improved both tribological behavior and corrosion resistance. These improvements have been attributed to superior mechanical properties, unique topological structure and high chemical stability of nanotubes.

Keywords: Carbon nanotubes; Electroless plating; Composite coating; Tribological behavior; Corrosion resistance

SMA-g-MPEG comb-like polymer as a dispersant for Al₂O₃ suspensions by Qianping Ran; Min Qiao; Jiaping Liu; Changwen Miao (pp. 2447-2453).

► Polycarboxylate-type comb-like polymer was first successfully employed as the dispersant for Al₂O₃ suspensions in this paper. ► The SMA-g-MPEG comb-like polymer was proven to be an excellent dispersant of Al₂O₃ suspensions. ► The impact of the length of side chains on the dispersion was investigated in detail. ► The comb-like polymer with mezzo length of side chains was found to be the best dispersant for Al₂O₃ suspensions.SMA-g-MPEG comb-like polymer is first employed as the dispersant of Al₂O₃ suspensions in this paper. The comb-like polymer has anionic polycarboxylate backbone, which makes the polymer easily absorbed on the cationic surface of Al₂O₃ particles; on the other hand, the comb-like polymer has hydrophilic MPEG side chains, which extend into the solution to provide steric repulsion after the comb-like polymer is absorbed on the surface of Al₂O₃ particles. The adsorption behavior, zeta potential, apparent viscosity, granularity and TEM images of the Al₂O₃ suspensions using SMA-g-MPEG as dispersant are investigated. The addition of SMA-g-MPEG improves the dispersibility and decreases the apparent viscosity of the Al₂O₃ suspension observably. The impacts of the length of side chains on the dispersion of Al₂O₃ suspensions are particularly discussed. The adsorbed molecular number of the dispersant decreased by increasing the length of side chains. The zeta potential of Al₂O₃ suspension is more negative by using comb-like polymer with shorter side chains. Based on the steric repulsion and adsorbed molecular number, SMA-g-MPEG with moderate length of side chain is found to have the best dispersibility for Al₂O₃ suspension.

Keywords: Comb-like polymer; SMA-g-MPEG; Al; ₂; O; ₃; Dispersant

Surface properties and water treatment capacity of surface engineered silica coated with 3-(2-aminoethyl) aminopropyltrimethoxysilane by Peter Majewski; Alexandra Keegan (pp. 2454-2458).

This study's focus was on the water-based, one-pot preparation and characterisation of silica particles coated with 3-(2-aminoethyl)aminopropyltrimethoxysilane (Diamo) and the efficiency of the material in removing the pathogens Escherichia coli, Pseudomonas aeruginosa, Mycobacterium immunogenum, Vibrio cholerae, poliovirus, and Cryptosporidium parvum. The water-based processing resulted in Diamo coated silica particles with significantly increased positive surface charge as determined by zeta potential measurements. In addition, X-ray photoelectron spectrometry of pure and Diamo coated silica confirmed the presence of Diamo on the surface of the particles. Thermogravimetric measurements and chemical analysis of the silica indicated a surface concentration of amine groups of about 1mmol/g_silica. Water treatment tests with the pathogens showed that a dose of about 10g appeared to be sufficient to remove pathogens from pure water samples which were spiked with pathogen concentrations between about 10² and 10⁴cfu/mL.

Keywords: Functionalised silica; Water treatment

Structural, optical and electrical properties of Cd-doped SnO₂ thin films grown by RF reactive magnetron co-sputtering by F. de Moure-Flores; J.G. Quiñones-Galván; A. Hernández-Hernández; A. Guillén-Cervantes; M.A. Santana-Aranda; M. de la L. Olvera; M. Meléndez-Lira (pp. 2459-2463).

► The physical properties of SnO₂:Cd were investigated as a function of the doping level. ► The obtained films have high transmittance and conductivity. ► The SnO₂:Cd films have potential as transparent electrodes.Transparent conducting SnO₂:Cd thin films were prepared by RF reactive magnetron co-sputtering on glass slides at a substrate temperature of 500°C using CdO as cadmium source. The films were deposited under a mixed argon/oxygen atmosphere. The structural, optical and electrical properties were analyzed as a function of the Cd amount in the target. The X-ray diffraction shows that polycrystalline films were grown with both the tetragonal and orthorhombic phases of SnO₂. The obtained films have high transmittance and conductivity. The figure of merit of SnO₂:Cd films are in the order of 10⁻³Ω⁻¹, which suggests that these films can be considered as candidates for transparent electrodes.

Keywords: Cd-doped tin oxide; Thin films; RF-magnetron sputtering; High transmittance; Transparent electrodes

Optical and hydrophilic properties of Cr doped TiO₂–SiO₂ nanostructure thin film by Akbar Eshaghi; Ameneh Eshaghi (pp. 2464-2467).

► The Cr doped TiO₂–SiO₂ thin film on glass substrate was deposited by a sol gel process. ► Cr doping decreased the band gaps of the TiO₂–SiO₂ thin film. ► The Cr doped TiO₂–SiO₂ thin film showed large photocatalytic activity to degradation of methyl orange.Cr doped TiO₂–SiO₂ nanostructure thin film on glass substrates was prepared by a sol–gel dip coating process. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the structural and chemical properties of the films. A UV–vis spectrophotometer was used to measure the transmittance spectra of the thin film. The hydrophilicity of the thin film during irradiation and storage in a dark place was measured by a contact angle analyzer. The results indicated that Cr doping has a significant effect on the transmittance and super-hydrophilicity of TiO₂–SiO₂ thin film.

Keywords: Sol–gel processes; Thin film; TiO; ₂; –SiO; ₂; Cr doping; Super-hydrophilicity

Superhydrophobic conductive textiles with antibacterial property by coating fibers with silver nanoparticles by Chao-Hua Xue; Jia Chen; Wei Yin; Shun-Tian Jia; Jian-Zhong Ma (pp. 2468-2472).

Display Omitted► Silver nanoparticles were in situ produced and coated on cotton fibers. ► Silver nanoparticle coated textiles became superhydrophobic after hydrophobization. ► Coating of silver on fibers made the textile conductive and antibacterial. ► Superhydrophobic multifunctional textiles were fabricated.Silver nanoparticles (Ag NPs) were produced on cotton fibers by reduction of [Ag(NH₃)₂]⁺ complex with glucose. Further modification of the fibers coated by Ag NPs with hexadecyltrimethoxysilane led to superhydrophobic cotton textiles. Scanning electron microscopy images of the textiles showed that the treated fibers were covered with uniform Ag NPs, which generate a dual-size roughness on the textiles favouring the formation of superhydrophobic surfaces, and the Ag NPs formed dense coating around the fibers rendering the intrinsic insulating cotton textiles conductive. Antibacterial test showed that the as-fabricated textiles had high antibacterial activity against the gram-negative bacteria, Escherichia coli. These multifunctional textiles might find applications in biomedical electronic devices.

Keywords: Superhydrophobic; Conductive; Textiles; Antibacterial; Silver nanoparticles

Graphene–CdS composite, synthesis and enhanced photocatalytic activity by Zhiyong Gao; Ning Liu; Dapeng Wu; Wenguang Tao; Fang Xu; Kai Jiang (pp. 2473-2478).

Display Omitted► Graphene–CdS composites with uniform scattering of CdS on graphene sheets were synthesized by hydrothermal method. ► The graphene–CdS composites demonstrated improved visible light induced photocatalytic activity and well stability. ► The photodegradation mechanism was investigated using fluorescence technique and analyzed from thermodynamics viewpoint.Graphene–CdS (G–CdS) composites were synthesized through a simple solvothermal method. The formed CdS nanospheres were homogeneously scattered on the surface of graphene sheets. Fluorescence quenching effect of the G–CdS composites indicated effective transfer of photo-excited electrons from CdS to graphene, suppressed the recombination of photo-generated electron–hole pairs, so that the enhanced visible light induced photodegradation activity for Rhodamine B (RhB) was achieved. Based on the high photocatalytic activity and well stability, the G–CdS composite containing 70% CdS can be expected to be a practical visible light photocatalyst.

Keywords: Graphene–CdS composites; Photocatalysis; Fluorescence; Hydroxyl radicals

Effect of annealing temperature and annealing atmosphere on the structure and optical properties of ZnO thin films on sapphire (0001) substrates by magnetron sputtering by Lin Cui; Hua-Yu Zhang; Gui-Gen Wang; Fang-Xu Yang; Xu-Ping Kuang; Rui Sun; Jie-Cai Han (pp. 2479-2485).

ZnO thin films were epitaxially grown on sapphire (0001) substrates by radio frequency magnetron sputtering. ZnO thin films were then annealed at different temperatures in air and in various atmospheres at 800°C, respectively. The effect of the annealing temperature and annealing atmosphere on the structure and optical properties of ZnO thin films are investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL). A strong (002) diffraction peak of all ZnO thin films shows a polycrystalline hexagonal wurtzite structure and high preferential c-axis orientation. XRD and AFM results reveal that the better structural quality, relatively smaller tensile stress, smooth, uniform of ZnO thin films were obtained when annealed at 800°C in N₂. Room temperature PL spectrum can be divided into the UV emission and the Visible broad band emission. The UV emission can be attributed to the near band edge emission (NBE) and the Visible broad band emission can be ascribed to the deep level emissions (DLE). By analyzing our experimental results, we recommend that the deep-level emission correspond to oxygen vacancy (V_O) and interstitial oxygen (O_i). The biggest ratio of the PL intensity of UV emission to that of visible emission ( I_NBE/ I_DLE) is observed from ZnO thin films annealed at 800°C in N₂. Therefore, we suggest that annealing temperature of 800°C and annealing atmosphere of N₂ are the most suitable annealing conditions for obtaining high quality ZnO thin films with good luminescence performance.

Keywords: ZnO; Magnetron sputtering deposition; Annealing; X-ray diffraction; Photoluminescence

Theoretical studies of the structure of C₂H₂ adsorbed on Si(001) by Tai-Quan Wu; Ping Zhu (pp. 2486-2489).

► The MSC calculation shows there is only one possible structure model when C₂H₂ adsorbed on Si(001)-(2×1) surface. ► The calculated curves of the coexistence of the dimerized structure and the rotational one are in good agreement with the experimental data, not the coexistence of the dimerized and end-bridge structures.The carbon 1s near-edge X-ray absorption fine structure (NEXAFS) spectra of the acetylene (C₂H₂) at 1ML coverage adsorbed on the Si(001)-(2×1) surface at room temperature have been investigated by multiple-scattering cluster (MSC). The MSC result shows that the correct adsorption model of C₂H₂/Si(001)-(2×1) is unique, i.e. the dimerized structure with two domains, (2×1) and (1×2).

Keywords: PACS; 61.10.HtC; ₂; H; ₂; /Si(0; 0; 1)-(2; ×; 1); Near edge X-ray absorption fine structure (NEXAFS); Multiple-scattering cluster method (MSC); Dimerized structure

An upgraded TOF-SIMS VG Ionex IX23LS: Study on the negative secondary ion emission of III–V compound semiconductors with prior neutral cesium deposition by C.A.A. Ghumman; A.M.C. Moutinho; A. Santos; O.M.N.D. Teodoro; A. Tolstogouzov (pp. 2490-2497).

► Newly developed data acquisition and control system for TOF-SIMS VG Ionex IX23LS. ► Neutral Cs deposition onto surface of III–V semiconductors prior to SIMS analysis. ► Surface cesiation enhances the peak intensity of all negative ion species. ► An enhancement is larger for In-based than for Ga-based compounds. ► The greater bond ionicity of In-based compound is responsible for such an enhancement.A TOF-SIMS VG Ionex IX23LS with upgraded data acquisition and control system was used to study the secondary emission of negative atomic and cluster ions of non-metallic elements (P, As and Sb) upon a 19keV Ga⁺ bombardment of non-degenerated III–V semiconductors (GaP, GaAs, GaSb, InP, InAs and InSb) with prior neutral Cs deposition from a getter dispenser. It was found that surface cesiation enhances the peak intensity of all negative ion species; in the case of atomic ions, the greatest increase (360) was observed for P⁻ emitted from InP. Such an enhancement was larger for In-based than for Ga-based compounds. We explained that in terms of an electronegativity difference between the composing atoms of III–V semiconductors. The greater electronegativity difference (bond ionicity) of In-based compounds resulted in the greater Cs-induced work function decrease leading to a higher increase in the ionization probability of secondary ions.

Keywords: TOF-SIMS; III–V semiconductors; Neutral cesium deposition; Work function; Secondary ion yield enhancement; Electronegativity

Hydrogen storage in different carbon materials: Influence of the porosity development by chemical activation by Vicente Jiménez; Ana Ramírez-Lucas; Paula Sánchez; José Luís Valverde; Amaya Romero (pp. 2498-2509).

► It was obtained a carbon material with hydrogen adsorption capacity of 4wt.%. ► It was study the hydrogen adsorption in different carbon materials. ► Activation process increased the hydrogen adsorption capacity by a factor of 4.5. ► It was correlated the adsorption capacity with surface area and pore volume.The hydrogen adsorption capacity of different types of carbon nanofibers (platelet, fishbone and ribbon) and amorphous carbon have been measured as a function of pressure and temperature. The results showed that the more graphitic carbon materials adsorbed less hydrogen than more amorphous materials. After a chemical activation process, the hydrogen storage capacities of the carbon materials increased markedly in comparison with the non-activated ones.BET surface area of amorphous carbon increased by a factor of 3.5 and the ultramicropore volume doubled, thus increasing the hydrogen adsorption by a factor of 2. However, BET surface area in platelet CNFs increased by a factor of 3 and the ultramicropore volume by a factor of 6, thus increasing the hydrogen storage by a factor of 4.5. The dependency of hydrogen storage capacity of carbon materials on the BET surface area was evaluated using both a condensation model and experimental results. Comparison of data suggests that the hydrogen adsorption capacity clearly depends on the pore structure and so, on the accessibility to the internal surface.

Keywords: Hydrogen storage; Carbon nanofibers; Chemical activation; Linear scaling; Surface area

Hydrothermal synthesis of highly nitrogen-doped carbon powder by Deyi Zhang; Yuan Hao; Ying Ma; Huixia Feng (pp. 2510-2514).

► Nitrogen-doped carbon powder was synthesized via hydrothermal treatment of sucrose. ► Precursor was prepared by aminization reaction between sucrose and ammonia. ► Dopant concentration can be adjusted by careful choice of the reaction conditions.Nitrogen-doped carbon powder (NCP) with high and controllable dopant concentration was facilely synthesized via hydrothermal treatment of sucrose under ammonia followed by calcination. The dopant concentration of the as-synthesized carbon powder can be easily adjusted in the range of 4.37–17.82wt.% by careful choice of the reaction conditions. The precursor with high nitrogen content was prepared by aminization reaction between sucrose and ammonia in hydrothermal condition, amine groups are successfully introduced into the precursor molecule, which groups convert finally to pyridinic-like and graphitic-like structure in the followed heat-treatment process. Various techniques, including the elemental analysis, TG–DTA, XPS, XRD, SEM and FTIR, were employed to characterize and assess the compositional and structural properties of the precursor and final nitrogen-doped materials. The present work propose a novel method for synthesis of highly nitrogen-doped carbon materials.

Keywords: Carbon; Nitrogen doping; Sucrose; Ammonia; Hydrothermal treatment

Photocatalytic activity of multielement doped TiO₂ in the degradation of congo red by R. Ramakrishnan; S. Kalaivani; J. Amala Infant Joice; T. Sivakumar (pp. 2515-2521).

Display Omitted► Nanosized titania catalyst was prepared successfully by sol–gel method. ► Doping of multielement over TiO₂ decreased the band gap. ► Increase in calcinations temperature resulted in of rutile phase formation. ► Maximum decolourisation of CR was obtained over CNBF/TiO₂ (600°C). ► Catalysts which are in rutile phase showed less photocatalytic activity.TiO₂ although considered a promising photocatalyst for the degradation of aqueous pollutants, it suffers from poor absorption in the visible region and hence requires ultraviolet (UV) light for activation. To make TiO₂ a visible active photocatalyst, multielement (C, N, B, and F) doping has been done. The synthesised CNBF/TiO₂ catalysts were calcined at different temperatures and characterized by XRD, BET surface area, UV DRS, XPS, HRSEM–EDAX, and TEM techniques. These catalysts found to show less band gap values when compared to bare TiO₂. These catalysts were tested for their catalytic activity towards the degradation of a textile dye – congo red (CR) under different reaction conditions. It was found that the photocatalytic activity was dependent on both doping of multielement and the calcination temperature of CNBF/TiO₂. The co-doped catalysts which were calcined at 400°C and 600°C (100% intensity in anatase phase) were found to be the best catalysts (100% decolourisation of CR in 21/2h and 2h respectively). TOC analysis carried out for the samples at the reaction time of 5h showed very high percentage (83%) degradation of CR over CNBF/TiO₂ catalysts calcined at 600°C when compared to the other catalysts calcined at different temperatures. CNBF/TiO₂ (1000°C) showed very less photocatalytic activity due to the formation of rutile phase.

Keywords: Photodegradation; Photodecolourisation; Element doped titania; Congo red; Multi lamp photo reactor; Pseudo first order

Classification of stacking faults and dislocations observed in nonpolar a-plane GaN epilayers using transmission electron microscopy by Bo Hyun Kong; Qian Sun; Jung Han; In-Hwan Lee; Hyung Koun Cho (pp. 2522-2528).

► We characterized various defects observed in a-plane GaN epilayers using TEM. ► We presented comparative discrimination methods to identify various line and planar defects observed in a-GaN. ► Investigations of the types of defects observed under different two-beam conditions of the various zone axes were performed in detail.In this study, we presented comparative discrimination methods to identify various line and planar defects observed in nonpolar a-GaN epilayers on r-sapphire substrates. Unlike the case of conventional c-GaN, which is dominated by perfect threading dislocations, systematic identification of undistinguishable defects using transmission electron microscopy (TEM) is necessary to suppress the propagation of defects in nonpolar GaN epilayers. Cross-sectional TEM images near the [0001] zone axis revealed that perfect mixed and pure screw type dislocations are visible, while pure edgeand basal stacking faults (BSFs) are not discernible. In tilted cross-sectional TEM images along the[12¯10] zone axis, the dominant defects were BSFs and partial dislocations for theg→=1¯010 and 0002 two-beam images, respectively. From plan-view TEM images taken along the[112¯0] axis, it was found that the dominant partial and perfect dislocations were Frank–Shockley and mixed dislocations, respectively. Prismatic stacking faults were observed as inclined line contrast near the [0001] zone axis and were visible as band contrast in the two-beam images along the[12¯10] and[112¯0] zone axes.

Keywords: PACS; 61.72.Ff; 68.37.Lp; 81.05.Ea; 81.15.GhDefects; Metalorganic chemical vapor deposition; Nitrides; Semiconducting III–V materials

Hydrophobic modification of wood via surface-initiated ARGET ATRP of MMA by Yanchun Fu; Gang Li; Haipeng Yu; Yixing Liu (pp. 2529-2533).

► ARGET ATRP is employed to graft MMA onto wood surface. ► Both the ratio of sacrificial initiator to the monomer and the polymerization time positively influence the amount of MMA polymer grafting. ► Hydrophobic wood surface with contact angles ranged from 101.5̊ to 130̊.To convert the hydrophilic surface of wood into a hydrophobic surface, the present study investigated activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP) as a method of grafting methyl methacrylate (MMA) onto the wood surface. The wood treated with 2-bromoisobutyryl bromide and with the subsequently attached MMA via ARGET ATRP under different polymerization times (2h, 4h, 6h, 8h) were examined using scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. All the analyses confirmed that PMMA had been grafted onto the wood surface. Water contact angle measurement proved that the covering layer of PMMA on wood made the surface hydrophobic. Polymerization time had a positive influence on the contact angle value and higher contact angle can be produced with the prolongation of the polymerization time. When the reaction time was extended to 8h, the contact angle of treated wood surface reached 130° in the beginning, and remained at 116° after 60s. The ARGET ATRP method may raise an alteration on the wood surface modification.

Keywords: ARGET ATRP; Wood; MMA; Hydrophobic; Surface modification

Simultaneous determination of cation exchange capacity and surface area of acid activated bentonite powders by methylene blue sorption by Nilgün Yener; Cengiz Biçer; Müşerref Önal; Yüksel Sarıkaya (pp. 2534-2539).

The ion exchanged ( m_ex) and physically adsorbed ( m_ad) methylene blue contents were obtained as the values of sorption capacity at c=0 and the increase to a plateaus of adsorption isotherms, respectively. The m_ad value was taken to be monolayer adsorption capacity. Cation exchange capacity and specific surface area for each powder were calculated from the m_ex and m_ad values, respectively.Display Omitted► Modification of the ionic surfaces of a bentonitic clay by acid treatment. ► Cation exchange capacity of the ionic solids. ► Determination of surface area from physical adsorptions. Correlation between methylene blue and nitrogen surfaces areas.To distinguish the ion exchanged and physically adsorbed methylene blue cations (MB⁺) on ionic surfaces, acid activated bentonite samples were used as porous adsorbents. A natural calcium bentonite (CaB) sample from Enez/Edirne, Turkey, was acid activated at 90°C for 16h with various HCl/CaB ratios. The irreversible exchange and physical adsorption of MB⁺ cations on the ionic solids have simultaneously occurred. The ion exchanged ( m_ex) and physically adsorbed ( m_ad) MB⁺ contents were obtained as the values of sorption capacity at c=0 and the increase to a plateaus of adsorption isotherms, respectively. The m_ad value was taken to be monolayer adsorption capacity. Cation exchange capacity ( CEC) and specific surface area ( S_MB) for each sample were calculated from the m_ex and m_ad values, respectively. Also, the BET specific surface areas ( S_BET) and pore size distribution were determined from low temperature nitrogen adsorption/desorption data. A linear correlation between the S_MB and S_BET values was found.

Keywords: Methylene blue; Bentonite; Smectite; Acid activation; Cation exchange capacity; Surface area

Synthesis of nanocomposites based on nanotubes and silicates by J. Breza; K. Pastorková; M. Kadlečíková; K. Jesenák; M. Čaplovičová; M. Kolmačka; F. Lazišťan (pp. 2540-2543).

► Preparation of nanocomposites based on carbon nanotubes and aluminosilicates. ► Base and tip growth of nanotubes. ► Nanotube bridges and grids. In situ synthesis of nanocomposites based on carbon nanotubes and zeolite/montmorillonite was carried out in a hot filament CVD reactor where the precursors (methane and hydrogen) are activated by carbonized tungsten filaments heated up to 2200°C. In nanocomposites formed both on zeolite and montmorillonite we observed cross-linking of the catalytic particles by nanotubes and creation of carbon nanotube bridges and three-dimensional networks. The length of nanotube bridges was in a range from several nm to nearly 10μm. A high density of carbon nanotubes was observed in the whole volume of zeolite. The high catalytic efficiency of zeolite is most likely caused by its structure that allows anchoring of Fe³⁺ catalytic particles in the pores and prevents their migration from the sample. At the ends of the nanotubes grown on zeolite we observed particles of the catalyst. In montmorillonite, the particles catalyzing the growth of carbon nanotubes may be present not only on the external surface but also in the interlayer voids of the mineral. Its catalytic efficiency is enhanced as proved by the higher amount of CNTs and their bundles. In the course of CNTs synthesis probably also clumps of Fe³⁺ catalytic particles arise, which may be the reason for formation of bundles of nanotubes.

Keywords: Carbon nanotube; Aluminosilicate; Zeolite; Montmorillonite

Fabrication of superhydrophobic coating via a facile and versatile method based on nanoparticle aggregates by Zhoukun He; Meng Ma; Xiangchuan Xu; Jianying Wang; Feng Chen; Hua Deng; Ke Wang; Qin Zhang; Qiang Fu (pp. 2544-2550).

The multi-scale structures and formed networks of SiO₂ nanoparticle aggregates can be observed clearly by SEM and treated AFM images. The large area superhydrophobicity is readily regenerated after mechanical damage.Display Omitted► A facile and versatile method is provided to fabricate superhydrophobic coating. ► Multi-scale structures and the networks of nanoparticle aggregates are shown more clearly with treated AFM images. ► The networks of nanoparticle aggregates are equally important for surface superhydrophobicity with multi-scale structures. ► The large area superhydrophobic surface is long-term stable and readily regenerated after mechanical damage. ► The provided method is facile and versatile enough to be expanded to other approaches to obtain superhydrophobicity.Herein, we report a facile and low cost method for the fabrication of superhydrophobic surface via spin coating the mixture of polydimethylsiloxane precursor (PDMS) and silicon dioxide (SiO₂) nanoparticles. The surface hydrophobicity can be well tuned by adjusting the weight percent of PDMS and SiO₂. The water contact angle (WCA) can increase from 106.8±1.2° on PDMS film to 165.2±2.3° on PDMS/SiO₂ coating, companying with a change from adhering to rolling which was observed from tilting angle (TA) characterization. Multi-scale physical structures with SiO₂ nanoparticle aggregates and networks of SiO₂ nanoparticle aggregates are characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM), and they can be observed more clearly from the AFM images treated with software (WSxM). Then the relationship between surface hydrophobicity and structures is further discussed based on Wenzel and Cassie models, indicating that the appearance of networks of nanoparticle aggregates is important in the Cassie state. The superhydrophobic coating can keep the superhydrophobicity at least for one month under environment conditions and readily regenerate after mechanical damage. Additionally, the superhydrophobic coating can be fabricated using other methods including dip coating, spray coating and casting. Thus, a large area of superhydrophobic coatings can be easily fabricated. Therefore the range of possible applications for these facile and versatile methods can be expanded to various actual conditions.

Keywords: Superhydrophobic; Nanoparticle aggregate; Network; Silicon dioxide; PDMS

Studies on adsorptions of metallic ions in water by zirconium glyphosate (ZrGP): Behaviors and mechanisms by Yunjie Jia; Yuejuan Zhang; Runwei Wang; Faying Fan; Qinghong Xu (pp. 2551-2561).

A new layered materials of zirconium glyphosate (ZrGP) was studied on adsorptions to some metallic ions. Results indicate that ZrGP exhibited a high selective adsorption to Pb²⁺, and the loaded ZrGPs could be regenerated effectively by HCl solution. Memory effect on structural of ZrGP was also found when it was used as adsorbent on adsorption of Mg²⁺ and Ca²⁺ ions.Display Omitted► ZrGP exhibits a high selective adsorption to Pb²⁺. ► Adsorbed ZrGP can be regenerated effectively without capacity loss. ► ZrGP has memory effect on structural after M²⁺ ions (M²⁺ is Mg²⁺ and Ca²⁺ ions) were desorbed.A new adsorbent named zirconium glyphosate [Zr(O₃PCH₂NHCH₂COOH)₂·0.5H₂O, denoted as ZrGP] and its selective adsorptions to Pb²⁺, Cd²⁺, Mg²⁺ and Ca²⁺ ions in water were reported in this paper. Compared to other zirconium adsorbents, such as zirconium phosphate [Zr(HPO₄)₂], ZrGP exhibited highly selective adsorption to Pb²⁺ in solution which contained Pb²⁺, Cd²⁺, Mg²⁺ and Ca²⁺ ions. The loaded ZrGP with metallic ions can be efficaciously regenerated by aqueous solution of HCl (1.0M) without any noticeable capacity loss, and almost all of it can be reused and recycled. The memory effect on structural regeneration of ZrGP was also found when Mg²⁺ and Ca²⁺ were adsorbed. To be specific, the structure of ZrGP was destroyed due to adsorbing these two ions, but it could be regenerated after the loaded materials were dipped in HCl solution (1.0M) for several minutes to remove metallic ions.

Keywords: Adsorption; Desorption; Memory effect; Metallic ions

Deep reduction behavior of iron oxide and its effect on direct CO oxidation by Changqing Dong; Xinglei Liu; Wu Qin; Qiang Lu; Xiaoqiang Wang; Simo Shi; Yongping Yang (pp. 2562-2569).

► Electron transfer and repopulation play a direct role on each step of CO oxidation. ► Generation of atomic oxygen at the transition state acts as the key step for CO oxidation. ► Reasonable control of the degree of reduction favors CO oxidation and optimization of chemical looping combustion.Reduction of metal oxide oxygen carrier has been attractive for direct CO oxidation and CO₂ separation. To investigate the reduction behaviors of iron oxide prepared by supporting Fe₂O₃ on γ-Al₂O₃ and its effect on CO oxidation, fluidized-bed combustion experiments, thermogravimetric analyzer (TGA) experiments, and density functional theory (DFT) calculations were carried out. Gas yield(γCO2) increases significantly with the increase of temperature from 693K to 1203K, while carbon deposition decreases with the increase of temperature from 743K to 1203K, where temperature is a very important factor for CO oxidation by iron oxide. Further, it were quantitatively detected that the interaction between CO and Fe₂O₃, breakage of O–Fe bonds and formation of new C–O bonds, and effect of reduction degree were quantitatively detected. Based on adsorptions under different temperatures and reducing processes from Fe³⁺ into Fe²⁺, Fe⁺ and then into Fe, it was found that Fe²⁺→Fe⁺ was the reaction-controlling step and the high oxidation state of iron is active for CO oxidation, where efficient partial reduction of Fe₂O₃ into FeO rather than complete reduction into iron may be more energy-saving for CO oxidation.

Keywords: CO oxidation; Iron oxide; Chemical-looping; Density functional theory

Synthesis of water-soluble FeOOH nanospindles and their performance for magnetic resonance imaging by Leyong Zeng; Wenzhi Ren; Jianjun Zheng; Aiguo Wu; Ping Cui (pp. 2570-2575).

► A simple and green method was developed for the synthesis of FeOOH nanospindles. Due to the absence of additional organic reaction agents, the as-prepared FeOOH nanospindles would benefit for the applications in biomedicine. ► A simple and green method was developed for the synthesis of FeOOH nanospindles. Due to the absence of additional organic reaction agents, the as-prepared FeOOH nanospindles would benefit for the applications in biomedicine. ► The as-prepared FeOOH nanospindles showed T₁- and T₂-weighted magnetic resonance imaging (MRI) performance, and will have potential as MRI contrast agents.Water soluble FeOOH nanospindles with small size were synthesized by a simple hydrolysis method of inorganic salts and water bath treatment with different incubation time. The morphology, microstructure, magnetic resonance imaging (MRI) performance and cytotoxicity of the as-prepared FeOOH nanospindles were investigated, respectively. The results showed that the longitudinal length of FeOOH nanospindles was about 40–50nm, and the incubation time had important effect for the morphology and production rate of FeOOH nanospindles. MRI test showed that the longitudinal and transverse relaxivities ( r₁ and r₂ values) of FeOOH nanospindles were about 3.06mM⁻¹s⁻¹ and 5.06mM⁻¹s⁻¹, respectively. Furthermore, the experimental results of the Prussian Blue staining showed the clusters of FeOOH nanospindles in the cytoplasm of the labeled cells, and the cytotoxicity characterization indicated that FeOOH nanospindles have low cytotoxicity. Therefore, the as-prepared FeOOH nanospindles will have potential applications as T₁- and T₂-weighted MRI contrast agents.

Keywords: FeOOH nanospindles; Magnetic resonance imaging; Cytotoxicity

Experimental and numerical study of surface alloying by femtosecond laser radiation by E.L. Gurevich; S. Kittel; R. Hergenröder (pp. 2576-2579).

► We study femtosecond-laser induced metal alloying experimentally. ► We produce a sandwich-like structure by evaporating Au then Cu on glass substrate. ► XPS in-depth profiling reveals metal mixing on the Au/Cu interface after the laser alloying. ► Dependence of the mixed layer thickness on the processing parameters is studied.Here we report on experimental studies of femtosecond laser induced surface metal alloying. We demonstrate that layers of different metals can be mixed in a certain range of laser pulse energies. Numeric simulations demonstrate that the sub-surface melting and mixing is advantaged through the difference in the electron–phonon coupling constants of the metals in the multi-layer system. Dependence of the depth of the mixed layer on the number of laser pulses per unit area is studied. Numeric simulations illustrate physical picture of the laser alloying process.

Keywords: PACS; 61.80.Ba; 81.40.Wx; 68.37.−dFemtosecond laser; Surface alloying; X-ray photoelectron spectroscopy

Modelling the formation of nanostructures on metal surface induced by femtosecond laser ablation by M. Djouder; T.E. Itina; D. Deghiche; O. Lamrous (pp. 2580-2583).

Simulation results obtained for circular polarization (after ∼10fs, laser electrical field of 10⁹V/m, λ_D=7×10⁻¹¹m): (a) electronic density profile and (b) surface electrical field profile.Display Omitted► We use the PIC method to simulate the interaction of femtosecond laser with a metallic target. ► We characterize the rippling phase. ► We provide new insights into the mechanisms responsible for surface grating formation.We employ the particle-in-cell method to simulate the mechanisms of femtosecond (fs) laser interactions with a metallic target. The theoretical approach considers the solid as a gas of free electrons in a lattice of immobile ions and the laser fluences close to the ablation threshold. At first moments of the interaction, our simulations mapped out different nanostructures. We carefully characterized the rippling phase and found that its morphology is dependent on the distribution of the electron density and the period of the ripples depends on the laser intensity. The simulation method provides new insights into the mechanisms that are responsible for surface grating formation.

Keywords: PACS; 62.20.M; 78.66.Tr; 78.47.−p; 79.20.Ds; 81.16.RfFemtosecond laser; Ablation; Nanostructure; Ripple; Particle in cell method; Modelling

Facile fabrication of SERS-active substrates based on discarded silver compact disks by Yonghai Song; Dan Luo; Shuhong Ye; Haoqing Hou; Li Wang (pp. 2584-2590).

. SERS-active substrates based on discarded silver (Ag) compact disks (CDs) were fabricated. The revealed Ag layer on the discarded CDs after removing its protective film can be used as SERS substrate directly and exhibited a good SERS activity.Display Omitted► SERS-active substrates based on discarded Ag compact disks (CDs) were fabricated. ► The Ag layer on CDs used as SERS substrate exhibited a good SERS activity. ► The Ag CDs roughened by electrochemical method improved its SERS activity greatly. ► A sandwich structure was fabricated to further improve the SERS activity.Surface-enhanced Raman spectroscopy (SERS) as a powerful analytical tool has gained extensive attention. Despite of many efforts in the design of SERS substrates, it still remains a grand challenge for creating a general substrate by a simple and low-cost way. Herein, we report our attempt to address this issue by fabricating SERS-active substrates based on discarded silver (Ag) compact disks (CDs). The revealed Ag layer on the CDs after removing its protective film can be used as SERS substrate directly and exhibited a good SERS activity. The Ag CDs was further roughened by electrochemical oxidation–reduction cycle in 0.1M KCl and improved its SERS activity greatly. The effects of roughened parameters on the SERS activity were investigated in detail. Moreover, a sandwich structure consisting of Ag nanoparticles, p-aminobenzenethiol and roughened Ag CDs was fabricated as an example to further enhance the SERS activity for detection in ultra-high sensitivity. These SERS-active substrates based on Ag CDs are all low-cost and allowing a “one way use”. The fabrication is also very simple and exhibits great potential for extensive application.

Keywords: Surface-enhanced Raman spectroscopy; Silver compact disks; Electrochemical oxidation–reduction cycle; p; -Aminobenzenethiol; Rhodamine 6G; Methylene blue

Effect of humidity and UV-assistance on the preparation of erbium doped alumina by aerosol MOCVD process by Rached Salhi; Carmen Jimenez; Patrick Chaudouët; Ramzi Maalej; Mohieddine Fourati; Jean-Luc Deschanvres (pp. 2591-2596).

► We have studied erbium doped aluminium oxide films deposited by aerosol-assisted MOCVD under high air humidity and with UV-assistance. ► The deposition rate increased and the activation energy of the deposition reaction was a small as 4kJ/mol. ► With UV and under high air humidity was improved films purity by facilitating removal of organic contamination from the growing surface. ► The films were shown a have high density and refractive index.The effect of deposition temperature, relative humidity of carrier gas and UV-assistance on the growth of Erbium-doped aluminium oxide films has been studied. The films were prepared from aluminium acetylacetonate (Al(C₅H₇O₂)₃) and erbium (III) Tris(2,2,6,6-tetramethyl-3,5-heptanedionate) (Er(TMHD)₃) by UV and aerosol-assisted metal–organic chemical vapour deposition, using air with controlled humidity as carrier gas. Amorphous transparent films were deposited between 350 and 460°C. It was observed that UV assistance allows a large decrease down to 5kJ/mol of the activation energy of the deposition reaction for deposition temperatures lower than 420°C. More over, depositing under high air humidity induced higher deposition rate, lower level of organic contamination and higher film density. Under these conditions Er-doped aluminium oxide films with a refractive index value of 1.71 were obtained at 460°C.

Keywords: Aerosol MOCVD; UV assistance; Humidity; Al; ₂; O; ₃; Er; Thin films; Structural and optical properties

Preparation of the Ni–P composite coating co-deposited by nano TiC particles and evaluation of it's corrosion property by S. Afroukhteh; C. Dehghanian; M. Emamy (pp. 2597-2601).

► Effects of different concentration of nano-sized TiC particles on the surface morphology, deposition rate and corrosion resistance of electroless Ni–P platings were investigated. ► With trapping TiC particles in EN coating, another nodular nucleation mechanism will be initiated. ► Addition of different concentrations of nano-sized TiC not only changed the surface morphology of the Ni–P coating, but also improves corrosion resistance significantly. ► The corrosion resistance increased despite the P content decreased with addition of TiC particles.In current research, low carbon steel plates were coated by Ni–P electroless method. The effect of adding different concentrations (ranging from 0.01g/l to 0.5g/l) of TiC nano-sized particles to the plating bath on deposition rate, surface morphology and corrosion behavior of Ni–P–TiC composite coatings were investigated. The surface morphology and the relevant structure were evaluated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Corrosion behavior of the coated steel was evaluated by electrochemical impedance spectroscopy (EIS) and polarization techniques. The results showed that addition of TiC nano-particles to Ni–P electroless bath not only changes the surface morphology of Ni–P coating, but also improves corrosion resistance of the steel in comparison with TiC free Ni–P electroless coating. In addition, the deposition rate of coating was also affected by incorporation of TiC particles. It was also found that improvement in corrosion resistance largely depends on the phosphorous and TiC concentrations on the coatings.

Keywords: Electroless; Composite coating; Titanium carbide; Morphology; Corrosion resistance

First-principles study on the catalytic role of Ag in the oxygen adsorption of LaMnO₃(001) surface by Yongjun Zhou; Zhe Lü; Pengzhen Guo; Yanting Tian; Xiqiang Huang; Wenhui Su (pp. 2602-2606).

► The catalytic role of Ag in the oxygen adsorption of LaMnO₃(001) surface. ► The most stable position for Ag adsorption is hollow site. ► Ag facilitate O₂ adsorption on surface. ► Ag facilitates O₂ molecule to dissociate to an O atom. ► Ag enhances the electrocatalytic activity of LaMnO₃ at low temperature.In the present paper, the catalytic role of Ag in the oxygen adsorption of LaMnO₃(001) surface has been theoretically investigated using first-principles calculations based on the density functional theory (DFT) and pseudopotential method. The O₂ adsorption energy is larger for the vertical adsorption and the covalent bond was formed between O₂ molecule and surface Mn. The calculation of electronic properties of interaction between Ag atom and LaMnO₃(001) surface demonstrates that the most stable position for Ag adsorption is hollow site. The O₂ adsorption energy dramatically increased from 0.298eV to 1.108eV due to Ag pre-adsorbed. It is Ag pre-adsorbed that facilitates O₂ adsorption on surface. The bond length and bond population of O₂ molecule indicate that Ag atom facilitates O₂ molecule dissociative adsorption. The Ag atom strengthens LaMnO₃(001) substrate activity and activity center was formed on surface, which enhances the electrocatalytic activity of LaMnO₃ as solid oxide fuel cells cathode material at low temperature.

Keywords: LaMnO; ₃; First-principles calculation; Ag catalytic; Solid oxide fuel cells

Synthesis and photocatalytic properties of porous TiO₂ films prepared by ODA/sol–gel method by Wenjie Zhang; Jiawei Bai (pp. 2607-2611).

► Porous TiO₂ films were deposited on glass-slides using octadecylamine template. ► Methyl orange degradation rate reached the maximal value at 2.0g addition of ODA. ► Activity of porous TiO₂ film decreased from 30.5% to 28.5% after 4 recycles.Porous TiO₂ films were deposited on SiO₂ pre-coated glass-slides by sol–gel method using octadecylamine (ODA) as template. The amount of ODA in the sol played an important role on the physicochemical properties and photocatalytic performance of the TiO₂ films. The films prepared at different conditions were all composed of anatase titanium dioxide crystals, and TiO₂ crystalline size got larger with increasing ODA amount. The maximum specific surface area of 41.5m²/g was obtained for TiO₂ powders prepared from titanium sol containing 2.0g ODA. Methyl orange degradation rate was enhanced along with increasing ODA amount and reached the maximal value at 2.0g addition of ODA. After 40min of UV-light irradiation, methyl orange degradation rate reached 30.5% on the porous film, which was about 10% higher than that on the smooth film. Porous TiO₂ film showed almost constant activity with slight decrease from 30.5% to 28.5% after 4 times of recycles.

Keywords: Sol–gel; Porous TiO; ₂; film; Octadecylamine; Photocatalysis

The role of target-to-substrate distance on the DC magnetron sputtered zirconia thin films’ bioactivity by Arisara Thaveedeetrakul; Nirun Witit-anun; Virote Boonamnuayvitaya (pp. 2612-2619).

► Zirconium dioxide thin films were synthesized by DC unbalanced magnetron sputtering with different target-to-substrate distance ( d_t-s). ► ZrO₂ thin film is composed of monoclinic phase only. ► Bone-like apatites were formed on the surface of the ZrO₂ thin film in SBF immersion experiments. ► The distance d_t-s greater than 80mm was found to be good condition for inducing the hydroxyapatite.Zirconium dioxide thin films were deposited on 316L-stainless steel type substrates using DC unbalanced magnetron sputtering. The process parameter of this work was the target-to-substrate distance ( d_t-s), which was varied from 60 to 120mm. The crystal structure and surface topography of zirconium dioxide thin films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). The results demonstrate that all of the ZrO₂ thin films are composed monoclinic phase. The film sputtered at short d_t-s (60mm) shows a rather heterogeneous, uneven surface. The grain size, roughness, and thickness of thin films were decreased by increasing d_t-s. The bioactivity was assessed by investigating the formation of hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) on the thin film surface soaked in simulated body fluids (SBF) for 7days. XRD and scanning electron microscopy (SEM) were used to verify the formation of apatite layers on the samples. Bone-like apatites were formed on the surface of the ZrO₂ thin film in SBF immersion experiments. A nanocrystalline hydroxyapatite (HA) with a particle size of 2–4μm was deposited. Higher crystallinity of HA on the surface was observed when the distance d_t-s increased to more than 80mm. Therefore, it seems that a d_t-s greater than 80mm is an important sputtering condition for inducing HA on the zirconia film.

Keywords: Zirconium dioxide; Magnetron sputtering; Simulated body fluid; Thin film; Hydroxyapatite

Study on the nano machining process with a vibrating AFM tip on the polymer surface by Weitao Liu; Yongda Yan; Zhenjiang Hu; Xuesen Zhao; Jiucun Yan; Shen Dong (pp. 2620-2626).

► The AFM tip in tapping mode is modeled as a driving oscillator with damping. ► The maximum contact pressure is used as a criterion to judge the deformation. ► Effects of factors on the nano machining process on polymer surfaces are studied.The polymer has been proved to be nano machined by a vibrating tip in tapping mode of Atomic Force Microscope (AFM). The force between the tip and the surface is an important factor which determines success of the machining process. Controlling this force with high accuracy is the foundation of nanomachining in AFM tapping mode. To achieve a deeper understanding on this process, the tip is modeled as a driving oscillator with damping. Factors affecting the nano machining process are studied. The Hertz elastic contact theory is used to calculate the maximum contact pressure applied by the tip which is employed as a criterion to judge the deformation state of the sample. The simulation results show that: The driven amplitude can be used as a main parameter of controlling the machined depth. Sharper tips and harder cantilevers should be used for successful nanomachining with the vibrating tip. Under the same conditions, a larger tip radius will not only result in the machining error, but also lead to failure of the nanomachining process. The higher driving frequency will lead to a larger tapping force. However it cannot be used as a parameter to control the machined depth because of its narrow variation range. But it is a main error source for the nanomachining process in AFM tapping mode. Moreover, a larger Young's modulus polymer sample will induce a smaller machined depth, a larger maximum contact pressure and a bigger tapping force.

Keywords: AFM; Tapping mode; Dynamic ploughing; Polymer; Nanomachining

Synthesis and characterization of Co/cenosphere core–shell structure composites by Xian-Feng Meng; Xiang-Qian Shen; Wei Liu (pp. 2627-2631).

► Co coated cenosphere composites are successfully fabricated by heterogeneous precipitation thermal reduction method using metal salts, ammonium hydro-carbonate and cenospheres as starting reagents for the first time. ► Relatively uniform, smooth and compact Co coating has been successfully coated onto cenospheres, and the grain size is about 24.5nm. ► The magnetic properties of Co coated cenosphere composites are affected by core layer.The cobalt film was successfully coated on the cenosphere particles using heterogeneous precipitation thermal reduction method. The morphology and microstructure of the products were analyzed by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). FE-SEM results implied that the Co film was relatively uniform and compact. XRD results indicated that the Co film coated on cenospheres was a face-centered cubic structure (fcc) and the crystallite size of Co particles was about 24.5nm. The magnetic property of Co/cenosphere composites was measured by vibrating sample magnetometer (VSM), and the results showed that the Co/cenosphere composites were of the weak soft magnetic property at room temperature, the Ms and Hc value was 18.2Am²kg⁻¹ and 28.4kAm⁻¹, respectively.

Keywords: Heterogeneous precipitation thermal reduction; Nano-Co; Fly-ash cenosphere; Nanoparticles; Composite materials

Bioactivity and cytocompatibility of dicalcium phosphate/poly (amino acid) biocomposite with degradability by Yunfei Zhang; Wenpeng Shan; Xiangde Li; Jie Wei; Hong Li; Jian Ma; Yonggang Yan (pp. 2632-2638).

A bioactive composite of dicalcium phosphate and poly (amino acid) was fabricated, and the in vitro bioactivity of the composite was investigated. The results indicated that the composite is bioactive with apatite formation on its surfaces after immersion into simulated body fluid for 7 days.Display Omitted► Dicalcium phosphate and poly (amino acid) bioactive composite. ► Apatite formed on composite surfaces after immersion into simulated body fluid. ► Composite could be slowly degradable in phosphate buffered saline. ► Dicalcium phosphate in composite improved cell proliferation and differentiation.A bioactive composite of dicalcium phosphate (DCP) and poly (amino acid) (PAA) was fabricated, and the in vitro bioactivity, degradability, and cellular responses to the DCP/PAA composite (DPC) were investigated as compared to PAA. Apatite formation on DPC surfaces occurred after immersion into simulated body fluid (SBF) for 7 days, but not on the surface of PAA. The weight loss ratio of DPC could reach 18.6±0.3wt% after soaking into phosphate buffered saline (PBS) for 2 months, which was higher than PAA (11.0±0.2wt%). Cell attachment and proliferation of MG-63 cells on DPC was obviously higher than on PAA. Moreover, the cells spread and formed confluent layer on the DPC surfaces. The alkaline phosphatase activity (ALP) of the cells on DPC was significantly greater than PAA at day 5 and day 7. The results suggested that introducing DCP into PAA makes the composite bioactive and more degradable, and meanwhile enhances osteoblast-like cells attach, proliferation and osteogenic differentiation.

Keywords: Dicalcium phosphate; Composite; Bioactivity; Degradation; Cytocompatibility

Site-specific electron-induced cross-linking of ortho-carborane to form semiconducting boron carbide by Frank L. Pasquale; Jeffry A. Kelber (pp. 2639-2642).

► Semiconducting boron carbide films were formed by electron beam bombardment of ortho-carborane. ► Site-specific decomposition and cross-linking between boron sites of adjacent icosahedra is the result of electron bombardment at 200eV. ► A surface photovoltage effect is observed in the valence band photoemission spectra after electron bombardment indicative of a p-type semiconductor.Semiconducting boron carbide (B₁₀C₂H_x) films have been formed by bombardment of condensed ortho-carborane (closo-1,2-dicarbadodecaborane) multilayers on polycrystalline copper substrates by 200eV electrons under ultra-high vacuum conditions. The film formation process was characterized by X-ray and ultraviolet photoelectron spectroscopies. Electron bombardment results in the cross-linking of the icosahedral units. The cross-linking is accompanied by a shift in the B(1s) binding energy indicating site-specific cross-linking between two boron sites on adjacent carborane icosahedra. An additional shift in valence band binding energies attributed to the surface photovoltage effect is indicative of the formation of a p-type semiconductor. This is the first report of B₁₀C₂H_x formation by electron bombardment of condensed films, and the data indicate that this method is a viable route towards formation of ultra-thin films of tailored composition and cross-linkages for emerging nanoelectronics and sensor applications.

Keywords: Boron carbide; Semiconducting solid films; Electron beam bombardment; UPS and XPS

The effect of pretreatment on adhesive strength of Cu-plated liquid crystal polymer (LCP) by Meisheng Zhou; Wenlong Zhang; Dongyan Ding; Ming Li (pp. 2643-2647).

► Potassium permanganate was found to be the most effective for pretreatment of LCP. ► The maximum adhesion strength was obtained, which is much higher than that of the reports. ► Hydrophilic groups and a nanometer-scale surface roughness were created on LCP surface by etching. ► The shearing failure mode was found to be dependent on the etching time.Copper metallization on LCP was carried out by means of electroless plating followed by electroplating and the effect of pretreatment on the adhesive strength of the Cu-plated LCP was investigated in detail. Compared with the other etching agents used here, potassium permanganate was found to be the most effective and the optimum etching time is 20min. With potassium permanganate as the etching agent, the adhesive strength could reach 12.08MPa, which is much higher than the reported maximum adhesive strength (lower than 8.0MPa). XPS spectra of LCP film indicated that hydrophilic groups were introduced into the LCP surface by etching, creating a nanometer-scale surface roughness and improving the wettability between copper and LCP. SEM and AFM observations revealed that the distinctly increased adhesive strength could be attributed to the improved wetting and the mechanical interlocking effect. The failure mode of Cu-plated LCP film was found to be dependent on the etching time. When the etching time was short, the failure mode of Cu-plated LCP film was mainly adhesive. As the etching time increased, cohesive failure gradually occurred, causing an adhesive/cohesive mixed failure mode.

Keywords: LCP film; Etching pretreatment; Adhesive strength

Molybdate and molybdate/permanganate conversion coatings on Mg–8.5Li alloy by Wang Guixiang; Zhang Milin; Wu Ruizhi (pp. 2648-2654).

Surface morphology of molybdate (a, 10g/L; b, 14g/L; c, 16g/L) and molybdate/permanganate (d, 14g/L molybdate+3.5g/L permanganate) conversion coating.Display Omitted► Molybdate and molybdate/permanganate conversion coatings have been formed on Mg–8.5Li alloy. ► The molybdate conversion coating had better corrosion resistance than bare alloy and chromate conversion coating. ► The molybdate/permanganate conversion coating performed better in certain condition than the molybdate conversion coating in 3.5% NaCl solution.A novel environment-friendly conversion coating for Mg–8.5Li alloy was obtained by immersing in a solution of molybdate. The concentration of ammonium molybdate and the addition of potassium permanganate were discussed in this experiment. The surface morphology of the conversion coatings was observed by scanning electron microscopy (SEM), and the chemical composition was investigated by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The corrosion resistance of Mg–8.5Li alloy and conversion coatings were investigated by means of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurement. The results showed that the coatings with cracked morphology were homogeneous and uniform. The conversion coatings were mainly composed of metal-oxide as detected by XPS. The results of electrochemical measurement and weight loss measurement revealed that the molybdate conversion coating had better corrosion resistance than bare alloy and chromate conversion coating, and the molybdate/permanganate conversion coating had lower corrosion current density and higher coating resistance than the molybdate conversion coating.

Keywords: Mg–Li alloy; Molybdate; Permanganate; Conversion coating; Corrosion resistance

In-situ formation of silver nanoparticles stabilized by amphiphilic star-shaped copolymer and their catalytic application by Xiujuan Huang; Yan Xiao; Wei Zhang; Meidong Lang (pp. 2655-2660).

Display Omitted► Silver nanoparticles were in situ synthesized by a “green” route. ► Polymeric micelles were utilized as nanoreactors for silver nanoparticles formation. ► PDMAEMA segments served as a reducing agent and a stabilizer.Silver nanoparticles (Ag NPs) were prepared via in situ reduction of silver nitrate (AgNO₃) using polymeric micelles as nanoreactors without any additional reductant. The micelles were constructed from the amphiphilic star-shaped copolymer composed of poly(ɛ-caprolactone) (PCL) segment, 2-(dimethylamino)ethyl methacrylate (DMAEMA or DMA) units and oligo(ethylene glycol)monomethyl ether methacrylate (OEGMA or OEG) units. The Ag NPs stabilized by those star-shaped copolymers were characterized using UV–vis spectrum, DLS, TEM and FTIR. It confirmed that PDMAEMA exhibited the reducing property unless pH was above 7. The Ag NPs were sphere-like with a diameter of 10–20nm, which was independent of the architecture of the copolymer and AgNO₃ concentration. Furthermore, the catalytic activity of these Ag NPs was investigated by monitoring the reduction of p-nitrophenol (4-NP) by NaBH₄. The result showed that the Ag NPs formed by coordination reduction can be effectively applied in catalytic reaction.

Keywords: Silver nanoparticles; Star-shaped copolymers; Coordination reduction; Nanoreactors; Catalytic activity

The growth of multi-walled carbon nanotubes on natural clay minerals (kaolinite, nontronite and sepiolite) by K. Pastorková; K. Jesenák; M. Kadlečíková; J. Breza; M. Kolmačka; M. Čaplovičová; F. Lazišťan; M. Michalka (pp. 2661-2666).

► Verification of the synthesis of nanocomposites based on carbon nanotubes and three microcrystalline phyllosilicates. ► Variability of phyllosilicates allows to prepare catalyst carriers with various contents of active metal. ► The type of catalyst carrier affects the morphology and structure of the final nanotube product markedly. ► Each of the prepared nanocomposites may be advantageous for a certain field of applications.The suitability of clay minerals – kaolinite, nontronite and sepiolite – is studied for synthesis of nanocomposites based on carbon nanotubes. Particles of iron were used as catalysts. Prior to synthesis, kaolinite and sepiolite were doped by the catalytically active metal, whereas in the case of nontronite the presence was used of this metal in the matrix of this mineral. Synthesis of CNTs was performed by hot filament chemical vapor deposition method. The produced nanocomposites were examined by transmission and scanning electron microscopies and energy dispersive X-ray spectroscopy. The experiment verified the potential of the three microcrystalline phyllosilicates for the growth of carbon nanotubes. Under the same technology conditions, the type of catalyst carrier affects the morphology and structure of the nanotube product markedly.

Keywords: Carbon nanotubes; CVD; Kaolinite; Nontronite; Sepiolite

Preparation and characterization of inorganic colored coating layers on lamellar mica-titania substrate by Min Ren; Hengbo Yin; Chaoqun Ge; Jichuan Huo; Xian Li; Aili Wang; Longbao Yu; Tingshun Jiang; Zhanao Wu (pp. 2667-2673).

The inorganic composite pigments, Fe₂O₃-, Bi₄Ti₃O₁₂-, and CoAl₂O₄-coated mica-titania, were prepared. The inorganic coating layers were anchored at mica-titania substrate surfaces tightly. The pigmentary performances of the inorganic composite pigments were significantly affected by the morphology and loading of inorganic coating layers.Display Omitted► Fe₂O₃-, Bi₄Ti₃O₁₂-, and CoAl₂O₄-coated lamellar mica-titania pigments were prepared. ► The coating layers were anchored at mica-titania substrates tightly. ► The morphology and loading of coating layers affected the pigmentary performances. ► The color and color purity of the mica-titania based inorganic pigments were tunable.The inorganic colored composite pigments, such as Fe₂O₃-, Bi₄Ti₃O₁₂-, and CoAl₂O₄-coated mica-titania composites, were prepared by hydrolysis of FeCl₃, Bi(NO₃)₃, and Co(NO₃)₂/Al(NO₃)₃ in the presence of mica-titania substrate and calcination at different temperatures. The inorganic coating layers on mica-titania substrate surfaces were explored by X-ray diffraction, scanning electron microscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. Dense and uniform Fe₂O₃ coating layers were formed on the surfaces of mica-titania substrates. At lower Bi₂O₃ loading, Bi₄Ti₃O₁₂ nanoparticles were formed on the surfaces of mica-titania substrates. But at higher Bi₂O₃ loading, Bi₄Ti₃O₁₂ nanosheets were formed and perpendicularly oriented to the substrate surfaces. CoAl₂O₄ nanosheets were formed on the mica-titania substrates and perpendicularly oriented to the substrate surfaces. The pigmentary performances of the inorganic composite pigments were analyzed by CIE, indicating that red, yellow, and blue colored pigments were achieved by coating Fe₂O₃, Bi₄Ti₃O₁₂, and CoAl₂O₄ on mica-titania substrate surfaces, respectively. The pigmentary performances of the inorganic composite pigments were significantly affected by the morphology and loading of inorganic coating layers.

Keywords: Mica-titania; Inorganic coating layer; Composite; Pigmentary property

Effect of deposition temperature on orientation and electrical properties of (K_0.5Na_0.5)NbO₃ thin films by pulsed laser deposition by Aifen Tian; Wei Ren; Lingyan Wang; Peng Shi; Xiaofeng Chen; Xiaoqing Wu; Xi Yao (pp. 2674-2678).

► Lead-free ferroelectric K_0.5Na_0.5NbO₃ thin films have been prepared by pulsed laser deposition. ► The deposition temperature plays an important role in the structure, crystal orientation and electrical properties of the thin films deposited at a temperature range from 680°C to 760°C. ► The crystallization of the films improves with increasing deposition temperature. ► The thin film deposited at 760°C exhibits strong (001) preferential orientation, large dielectric constant of 930 and remnant polarization of 8.54μC/cm².Lead-free ferroelectric K_0.5Na_0.5NbO₃ (KNN) thin films have been prepared on Pt/TiO₂/SiO₂/Si substrates by pulsed laser deposition process. The structures, crystal orientations and electrical properties of thin films have been investigated as a function of deposition temperature from 680°C to 760°C. It is found that the deposition temperature plays an important role in the structures, crystal orientations and electrical properties of thin films. The crystallization of thin films improves with increasing deposition temperature. The thin film deposited at 760°C exhibits strong (001) preferential orientation, large dielectric constant of 930 and the remnant polarization of 8.54μC/cm².

Keywords: Lead-free potassium sodium niobate; Thin films; Pulsed laser deposition; Dielectric and ferroelectric properties

Dependence of developing magnetic hysteresis characteristics on stages of evolving microstructure in polycrystalline yttrium iron garnet by N. Rodziah; M. Hashim; I.R. Idza; I. Ismayadi; A.N. Hapishah; M.A. Khamirul (pp. 2679-2685).

► Parallel evolutions of morphological and magnetic properties and their relationships at various sintering temperatures. ► A complete phase of Yttrium Iron Garnet was formed at sintering temperature lower than that in the conventional technique. ► 3 hysteresis loop groups evolved indicating three evolution stages: weak, moderate and strong ferromagnetism. ► Phase purity, crystallinity and microstructural effect clearly described the evolution of these 3 groups of hysteresis loops. ► Crystallinity could be estimated from B_s and M_s value; magnetization process could be identified from H_c value at particular grain size.The microstructure evolution in several polycrystalline yttrium iron garnet samples as a result of a sintering scheme was studied in detail, in parallel with the changes in their magnetic properties. Samples with nanometer sized starting powder were synthesized by employing the High-Energy Ball Milling technique and then sintering toroidal compacts of the milled powder. Nine sintered samples were obtained, each corresponding to a particular sintering from 600°C to 1400°C. The samples were characterized for their evolution in crystalline phases, microstructure and magnetic hysteresis-loops parameters. The results showed an increasing tendency of the saturation magnetization and saturation induction with grain size, which is attributed to crystallinity increase and to reduction of demagnetizing fields in the grains. The variation in coercivity could be related to anisotropy field changes within the samples due to grain size changes. In particular, the starting appearance of room temperature ferromagnetic order suggested by the sigmoid-shaped B–H loops seems to be dependent on a sufficient number of large enough magnetic domain-containing grains having been formed in the microstructure. Viewed simultaneously, the hysteresis loops appear to belong to three groups with different magnetism-type dominance, respectively dependent on phase purity and three different groups of grain size distributions.

Keywords: Sintering temperature; Microstructure; Magnetic properties; B–H hysteresis behaviour

Surface oxidability of pure liquid metals and alloys by E. Arato; M. Bernardi; D. Giuranno; E. Ricci (pp. 2686-2690).

► Evaporation and diffusion phenomena are driving the liquid metal surface oxidation. ► A pseudo-thermodynamics approach describes the surface oxidation mechanisms. ► The formation of volatile oxides prevents surface oxidation of liquid metals. ► Dynamic surface tension measurements successfully validate the theory.The analysis of the oxygen–liquid metal interaction is a topic of particular technological interest. A deep knowledge of the kinetics and transport mechanisms involved in the oxidation phenomena is necessary: the effect of oxidation reactions taking place in the gas phase and the evaporation of oxides must be considered.This paper aims to review our works in order to provide a systematic analysis of the oxidation of pure metals and determine the most likely to keeping oxygen-free the surface in a binary alloy.In addition, the upgrading of this theoretical approach, here briefly described, is addressed to give a contribution to a better understanding of the evolution of oxidation phenomena close to the solid–liquid–gas interfaces.

Keywords: Metal and alloys; Interfaces; Oxidation; Transport mechanism

Plasma sprayed Al₂O₃/FeCrAl composite coatings for electromagnetic wave absorption application by Liang Zhou; Wancheng Zhou; Jinbu Su; Fa Luo; Dongmei Zhu; Yanli Dong (pp. 2691-2696).

► Microstructure shows a uniform dispersion of metal particles with litter pores. ► Relaxation polarization and interfacial polarization would contribute to enhance ɛ′. ► Loss associated with relaxation polarization is the dominating factor enhancing ɛ″. ► The optimal reflection loss exceeds −10dB in 9.1–10.6GHz when the thickness is 1.3mm.Al₂O₃/FeCrAl composite coatings were fabricated by atmosphere plasma spraying technique. Microstructure and dielectric properties in the frequency range from 8.2 to 12.4GHz were investigated. The microstructure of composite coatings shows a uniform dispersion of metal particles with litter pores and microcracks in the composite coatings. The relaxation polarization and interfacial polarization in the coatings would contribute to enhance ɛ′ with rising FeCrAl content, and the associated loss could be considered as a dominating factor enhancing ɛ″. By calculating the microwave-absorption as a single-layer absorber, for the composite coatings with 41wt.% FeCrAl content, the reflection loss values exceeding −10dB are achieved in the frequency range of 9.1–10.6GHz when the coating thickness is 1.3mm.

Keywords: Plasma spraying; Dielectric properties; Radar absorbing coating; Al; ₂; O; ₃; /FeCrAl composite coatings

Double-chain phospholipid end-capped polyurethanes: Synthesis, characterization and platelet adhesion study by Dongsheng Tan; Xiaoqing Zhang; Jiehua Li; Hong Tan; Qiang Fu (pp. 2697-2706).

Top surface view of polyurethane film (a) and phosphorylcholine-analogue end-capped polyurethane film (b). Dark lines: hard segment domains; blue dots: phosphorylcholine-analogue.Display Omitted► A double-chain phospholipid was synthesized and end-capped to polyurethanes. ► Phospholipids enrich on the top surface (2nm) of polyurethanes. ► The phospholipid polyurethanes possess both anti-platelet adhesion property and good mechanical properties simultaneously.A novel phospholipid containing double chains and phosphotidylcholine polar head groups, 2-(10-(2-aminoethylamino)-10-oxodecanamido)-3-(decyloxy)-3-oxopropyl phosphorylcholine (ADDPC), was synthesized and characterized. Two kinds of double-chain phospholipid end-capped polyurethanes with different soft segments were prepared. The structure of prepared polyurethanes was characterized by X-ray photoelectron spectroscopic (XPS), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectrometry and atomic force microscope (AFM), which indicated that the double-chain phospholipids enriched onto the top surface of the prepared polyurethane films. The preliminary evaluation of blood compatibility showed that these novel phospholipid end-capped polyurethanes could suppress platelet adhesion and activation effectively. This property did not depend on the chemical structure of polyurethanes. In addition, according to tensile test results, the phospholipid polyurethanes kept good mechanical properties in comparison with original polyurethanes. It is suggested that double-chain phospholipid end-caption has good potential for achieving both hemocompatibility and good mechanical properties simultaneously for polyurethanes.

Keywords: Polyurethane; Platelet adhesion; Mechanical properties; Phospholipid

A new model for thermodynamic analysis on wetting behavior of superhydrophobic surfaces by Hongyun Zhang; Wen Li; Guoping Fang (pp. 2707-2716).

Changes of droplet states while water being added into droplet (the microsyringe not being marked). (a) Initial state (being from less droplet after advancing), apparent CA of θ_w, radius of droplet and three-phase contact-line of R₁ (as known value) andr1=R1sinθw, respectively; (b) pre-advancing state (three-phase contact line not being moved) as the instantaneous state (unsteady), advancing angle of θ_a, radius of droplet and three-phase contact-line of R₂ and r₂= r₁, respectively; (c) advancing state (three-phase contact line having been moved away), CA back to θ_w, radius of droplet and three-phase contact-line of R₃ and r₃ ( r₃= r₂), respectively, the volume of droplet ( V₂, V₃ represents volume of the droplet in pre-advancing or advancing state, respectively) keeps constant from (b) to (c) (namely V₃= V₂); (d) overall diagram of Longitudinal section of changes of states passing through the center while droplet advancing; (e) and (f) longitudinal section diagram passing through the center, before and after advancing, respectively.Display Omitted► A dynamic equation is intuitively established between static apparent CA and θ_a or θ_r. ► The relationships are established between CA, CAH, CFE, FEB and micro/nanoscale. ► Change of surfaces free energy (CFE), as measurement of ability of droplet. ► New concept of free energy barrier (FEB) is presented to illustrate CAH from macroscopic. ► Making strict explanations in math on CAH along with relevant phenomena.Superhydrophobic surfaces have shown inspiring applications in microfluidics, and self-cleaning coatings owing to water-repellent and low-friction properties. However, thermodynamic mechanism responsible for contact angle hysteresis (CAH) and free energy barrier (FEB) have not been understood completely yet. In this work, we propose an intuitional 3-dimension (3D) droplet model along with a reasonable thermodynamic approach to gain a thorough insight into the physical nature of CAH. Based on this model, the relationships between radius of three-phase contact line, change in surface free energy (CFE), average or local FEB and contact angle (CA) are established. Moreover, a thorough theoretical consideration is given to explain the experimental phenomena related to the superhydrophobic behavior. The present study can therefore provide some guidances for the practical fabrications of the superhydrophobic surfaces.

Keywords: Superhydrophobic; Contact angle hysteresis; Changes of surface free energy; Free energy barrier; Symmetry

Ag-deposited silica-coated Fe₃O₄ magnetic nanoparticles catalyzed reduction of p-nitrophenol by Xiaoyan Du; Jiang He; Jie Zhu; Lijuan Sun; Songsong An (pp. 2717-2723).

► We have synthesized Ag-deposited silica-coated Fe₃O₄ magnetic nanoparticles through a simple electroless-deposition method. ► The catalytic activiey of the Ag-deposited silica-coated Fe₃O₄ magnetic nanoparticles was explored. ► We verified that the nanoparticle perform high efficiency in catalytic reduction of p-nirtophenol. ► The nanoparticles also can be used as convenient and efficient recyclable catalyst.In this paper, a novel approach was successfully developed for advanced catalyst Ag-deposited silica-coated Fe₃O₄ magnetic nanoparticles, which possess a silica coated magnetic core and growth active silver nanoparticles on the outer shell using n-butylamine as the reductant of AgNO₃ in ethanol. The as-synthesized nanoparticles have been characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), Fourier transform infrared spectra (FT-IR), vibration sample magnetometer (VSM), and have been exploited as a solid phase catalyst for the reduction of p-nitrophenol in the presence of NaBH₄ by UV–vis spectrophotometry. The obtained products exhibited monodisperse and bifunctional with high magnetization and excellent catalytic activity towards p-nitrophenol reduction. As a result, the as-obtained nanoparticles showed high performance in catalytic reduction of p-nitrophenol to p-aminophenol with conversion of 95% within 14min in the presence of an excess amount of NaBH₄, convenient magnetic separability, as well as remained activity after recycled more than 6 times. The Fe₃O₄@SiO₂–Ag functional nanostructure could hold great promise for various catalytic reactions.

Keywords: Fe; ₃; O; ₄; @SiO; ₂; –Ag magnetic nanoparticles; Silver deposition; p; -Nitrophenol; Catalytic activity

Ageing of nickel used as sensitive material for early detection of sudomotor dysfunction by Hanna Ayoub; Virginie Lair; Sophie Griveau; Anouk Galtayries; Philippe Brunswick; Fethi Bedioui; Michel Cassir (pp. 2724-2731).

► The surface ageing of nickel electrodes was studied for the development of non-invasive biomedical devices. ► Electrochemical measurements coupled to surface chemical characterizations (XPS, ToF-SIMS) were performed on Ni samples, immersed in buffered chloride solutions. ► At anodic potentials, we showed that nickel was gradually passivated by a 1nm-thick duplex layer of nickel hydroxide and nickel oxide. ► At negative extended potentials, the inner layer was thickening, indicating a surface degradation of the nickel electrode. ► At breakdown potentials, ToF-SIMS imaged adsorbed chloride in pits.The surface ageing of nickel electrodes was studied in the frame of the development of non-invasive biomedical devices, dedicated to the detection of sudomotor dysfunction manifested by an alteration of the ionic balance in human sweat. In this kind of technology, low voltage potentials with variable amplitudes are applied to nickel electrodes, placed on skin regions with a high density of sweat glands, and the electrical responses are measured. The trick is that nickel electrodes play alternately the role of anode and cathode, thus the analysis of the temporal evolution of the physico-chemical properties of nickel is of prime importance to ensure the good performance of the device. Electrochemical measurements coupled to surface chemical characterizations (X-ray photoelectron spectroscopy (XPS), Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS)) were performed on pure Ni samples, immersed in buffered chloride solutions mimicking human sweat. The shapes of voltammograms, recorded in a restricted anodic potential range, show that the nickel surface was gradually passivated as a function of the number of scans. This was confirmed by XPS data, with the formation of a 1nm thick duplex layer composed by nickel hydroxide (outermost layer) and nickel oxide (inner layer). In a negative extended potential range, though the electrochemical behavior of electrodes was not modified upon cycling the potential, XPS data show that the inner layer was thickening, indicating a surface degradation of the nickel electrode. Below pitting potentials, adsorbed chloride was only hardly detected by XPS, and the surface composition of the nickel samples was similar after treatments in chloride or chloride-free buffered solutions. In a larger potential range enabling to reach the breakdown potential, the highly chemically sensitive ToF-SIMS characterization pointed out that the surface concentration of adsorbed chloride was higher in pits than elsewhere on the surface sample.

Keywords: Nickel; Ni ageing; Nickel oxide; XPS; ToF-SIMS; Electrochemistry; Chloride; Physiological pH; Synthetic sweat

Effect of precursor concentration and bath temperature on the growth of chemical bath deposited tin sulphide thin films by Y. Jayasree; U. Chalapathi; P. Uday Bhaskar; V. Sundara Raja (pp. 2732-2740).

► SnS is a potential solar cell absorber material. ► Effect of concentration of bath constituents and temperature on the CBD grown tin sulphide films. ► XRD and Raman Spectra for phase analysis.SnS is a promising candidate for a low-cost, non-toxic solar cell absorber layer. Tin sulphide thin films have been deposited by chemical bath deposition technique from a solution containing stannous chloride, thioacetamide, ammonia and triethanolamine (TEA). The effects of concentration of tin salt, triethanolamine and bath temperature on the growth of tin sulphide films have been investigated in order to optimize the growth conditions to obtain tin monosulphide (SnS) films. SnS films obtained under optimized conditions were found to be polycrystalline in nature with orthorhombic structure. The optical band gap of these films was found to be 1.5eV.

Keywords: SnS; Chemical bath deposition; Solar cell absorber; Triethanolamine; XRD; Band gap

Surface modification of the titanium implant using TEA CO₂ laser pulses in controllable gas atmospheres – Comparative study by J. Ciganovic; J. Stasic; B. Gakovic; M. Momcilovic; D. Milovanovic; M. Bokorov; M. Trtica (pp. 2741-2748).

► Surface modification of the titanium implant with nanosecond TEA CO₂ laser. ► Irradiation with high number of pulses in air, N₂, O₂ and He atmospheres. ► Surface roughness increased on the strictly localized area. ► Depending on the surrounding, titanium oxides and nitrides were formed. ► A sterilizing effect on localized surface area as a consequence of plasma formation.Interaction of a TEA CO₂ laser, operating at 10.6μm wavelength and pulse duration of 100ns (FWHM), with a titanium implant in various gas atmospheres was studied. The Ti implant surface modification was typically studied at the moderate laser beam energy density/fluence of 28J/cm² in the surrounding of air, N₂, O₂ or He. The energy absorbed from the TEA CO₂ laser beam is partially converted to thermal energy, which generates a series of effects, such as melting, vaporization of the molten material, shock waves, etc. The following titanium implant surface changes and phenomena were observed, depending on the gas used: (i) creation of cone-like surface structures in the atmospheres of air, N₂ and O₂, and dominant micro-holes/pores in He ambient; (ii) hydrodynamic features, most prominent in air; (iii) formation of titanium nitride and titanium oxide layers, and (iv) occurrence of plasma in front of the implant. It can be concluded from this study that the reported laser fluence and gas ambiences can effectively be applied for enhancing the titanium implant roughness and creation of titanium oxides and nitrides on the strictly localized surface area. The appearance of plasma in front of the implants indicates relatively high temperatures created above the surface. This offers a sterilizing effect, facilitating contaminant-free conditions.

Keywords: Titanium implant surface modification; Nanosecond TEA CO; ₂; laser; Laser-induced damage

Hydrogen adsorption on activated carbon nanotubes with an atomic-sized vanadium catalyst investigated by electrical resistance measurements by Ji Sun Im; Jumi Yun; Seok Chang Kang; Sung Kyu Lee; Young-Seak Lee (pp. 2749-2756).

The improved pore structure worked as a route for easy adsorption of hydrogen molecules in the carbon nanotubes, and the introduced vanadium catalyst played a role in high-efficiency hydrogen storage through the dissociation of hydrogen molecules in the spill-over phenomenon.Display Omitted► Investigation of hydrogen storage behavior by changes in electrical resistance. ► Creation of a pathway for hydrogen storage inside MWCNTs. ► Improvement of the specific surface area for hydrogen adsorption sites. ► Size-controlled vanadium catalyst to attract the electrons in the hydrogen molecule.Activated multi-walled carbon nanotubes were prepared with appended vanadium as a hydrogen storage medium. The pore structure was significantly improved by an activation process that was studied using Raman spectroscopy, field emission transmission electron microscopy and pore analysis techniques. X-ray photoelectron spectroscopy and X-ray diffraction results reveal that the vanadium catalyst was introduced into the carbon nanotubes in controlled proportions, forming V₈C₇. The improved pore structure functioned as a path through the carbon nanotubes that encouraged hydrogen molecule adsorption, and the introduced vanadium catalyst led to high levels of hydrogen storage through the dissociation of hydrogen molecules via the spill-over phenomenon. The hydrogen storage behavior was investigated by electrical resistance measurements for the hydrogen adsorbed on a prepared sample. The proposed mechanism of hydrogen storage suggests that the vanadium catalyst increases not only the amount of hydrogen that is stored but also the speed at which it is stored. A hydrogen storage capacity of 2.26wt.% was achieved with the activation effects and the vanadium catalyst at 30°C and 10MPa.

Keywords: Hydrogen storage; Carbon nanotube; Activation; Vanadium catalyst; Adsorption

Preferential surface oxidation of Gd in Gd₅Ge₄ by Chad D. Yuen; Gordon J. Miller; Patricia A. Thiel (pp. 2757-2760).

► Gd undergoes preferential oxidation at the (010) surface of Gd₅Ge₄, a model magnetocaloric material. ► The oxide covers or replaces Ge at the surface. ► Oxidation in vacuum is more extensive at 600K than at 300K.Gd oxidizes preferentially at the (010) surface of Gd₅Ge₄. This is consistent with thermodynamic data for the bulk oxides. Upon oxidation in vacuum, the gadolinium oxide displaces or covers the Ge. Oxidation is more extensive at 600K than at 300K, because more oxygen is incorporated into the surface and the shift of the Gd binding energy is larger.

Keywords: Binary alloy; X-ray photoelectron spectroscopy; Oxidation

Iron-containing coatings obtained by microplasma method on aluminum with usage of homogeneous electrolytes by A.B. Rogov; O.P. Terleeva; I.V. Mironov; A.I. Slonova (pp. 2761-2765).

► Alkaline homogeneous electrolyte with transition metal complexes. ► Coatings contain metallic iron and its oxides in alumina–silica matrix. ► Good reproducibility of coatings properties.The microplasma synthesis method of multicomponent oxide coatings including iron oxide on an aluminum alloy surface has been studied. The homogeneous electrolytes containing iron complexes with Edta⁴⁻ under pH 9–10 have been used. The dynamics reducing the pH of the electrolyte during formation process have been studied. The content of iron in the coatings has been measured spectrophotometricaly. Morphlogy and phase composition of the coatings have been studied by the scanning electron microscopy and X-ray powder diffraction.

Keywords: Microplasma electrochemical process; Aluminum alloy; Homogeneous electrolytes; Transition metal

Photocatalytic properties of TiO₂ thin films obtained by glancing angle deposition by Zhengcao Li; Yu Zhu; Qin Zhou; Jie Ni; Zhengjun Zhang (pp. 2766-2770).

► Nanostructured TiO₂ films were prepared by E-beam evaporation via Glancing Angle Deposition. ► Their structural, optical and photocatalytic properties have been investigated. ► The surface factor is proved a good parameter to estimate films’ surface area and to judge the photocatalytic property. ► The film's surface factor can be tuned to enhance photocatalytic activities by controlling the glancing angle.Titanium dioxide (TiO₂) thin films with different nanostructures such as nano-particles and separated vertical columns were grown by glancing angle deposition (GLAD) in an electron beam evaporation system. The photocatalytic properties of grown TiO₂ films with different deposition angles and different annealing temperatures were evaluated by following decomposition of methyl orange under ultraviolet (UV) light irradiation. The results suggest that increased surface area due to the GLAD process could improve the photocatalytic properties of TiO₂ films.

Keywords: Titanium dioxide; Glancing angle deposition; Photocatalytic properties

Molecular dynamics investigation of deposition and annealing behaviors of Cu atoms onto Cu(001) substrate by Xing-bin Jing; Zu-li Liu; Kai-lun Yao (pp. 2771-2777).

► The film grows approximately in a layer-island mode as the incident energy is from 1 to 5eV, while surface intermixing can be significantly observed at 10eV. ► The surface roughness of the film decreases with increasing the incident energy, and the film after annealing becomes smoother and more ordered. ► The radial distribution function, the residual stress, Poisson ratio and the density of thin film are obviously affected by substrate temperature and annealing process. ► High incident energy, substrate temperature and thermal annealing could help to enhance the surface morphology and promote the microstructure of the film.The deposition growth and annealing behaviors of Cu atoms onto Cu(001) are investigated in atomic scale by molecular dynamics (MD) simulation. The results indicate that the film grows approximately in a layer-island mode as the incident energy is from 1 to 5eV, while surface intermixing can be significantly observed at 10eV. The surface roughness of the film decreases with increasing the incident energy, and the film after annealing becomes smoother and more ordered. These phenomena may be attributed to the enhanced atomic mobility for higher incident energy and thermal annealing. It also indicates that atomic mixing is more significant with increasing both the incident energy and substrate temperature. In addition, the peak-to-peak distances of radial distribution function (RDF) clearly indicate that the films before and after annealing are still fcc structure except for that at the melting temperature of 1375.6K. After annealing, the film at the melting temperature returns to fcc structure instead of amorphous. Moreover, the residual stress and Poisson ratio of the film are remarkably affected by the thermal annealing. Furthermore, the density of thin film is obviously affected by the substrate temperature and annealing process. Therefore, one can conclude that high incident energy, substrate temperature and thermal annealing could help to enhance the surface morphology and promote the microstructure of the film.

Keywords: PACS; 68.35.Fx; 68.55.a; 81.40.Ef; 71.15.PdMD simulation; Annealing; Surface roughness; Radial distribution function

Preparation and tribological properties of stearic acid-modified hierarchical anatase TiO₂ microcrystals by Jianhua Qian; Xiangyu Yin; Ning Wang; Lin Liu; Jinjuan Xing (pp. 2778-2782).

► Hierarchical anatase TiO₂ microcrystals were synthesized through a facile solvothermal method. ► These TiO₂ microcrystals after surface modification could be readily dispersed in non-polar solvents. ► The modified TiO₂ microcrystals significantly improve tribological performances of liquid paraffin.Hierarchical TiO₂ microcrystals were synthesized through a facile solvothermal method. X-ray diffraction (XRD) and scanning electron microscope (SEM) measurements were used to characterize the structure of the as-prepared samples. The results indicated that the synthesized hierarchical titania (TiO₂) microspheres were composed of numerous anatase phase TiO₂ particles. The as-prepared samples were chemically modified with stearic acid to improve their dispersion in oil. Fourier transmission infrared spectroscopy (FT-IR) and thermogravimetry analysis (TGA) were carried out to evaluate the characteristics of the modified TiO₂ microcrystals. The tribological properties of the modified TiO₂ microcrystals as additives of liquid paraffin were studied by a four-ball tester, and the results showed that they could significantly improve anti-wear performance, friction-reduction property and load-carrying capacity of liquid paraffin. These advantages make the modified TiO₂ microcrystals promising for green lubricating oil additives.

Keywords: Hierarchical anatase TiO; ₂; microcrystal; Solvothermal synthesis; Surface modification; Tribological property

Enzymes immobilization on Fe₃O₄–gold nanoparticles by B. Kalska-Szostko; M. Rogowska; A. Dubis; K. Szymański (pp. 2783-2787).

► Core–shell magnetic nanoparticles were biofunctionalized. ► Trypsin and glucose oxidase was successfully immobilized at the particle surface. ► Characterization of obtained biocomposites was done by IR, DSC, XRD, TEM and Mossbauer spectroscopy.In the present study Fe₃O₄ magnetic nanoparticles were synthesized by coprecipitation of Fe²⁺ and Fe³⁺ from chlorides. In the next step magnetite–gold core–shell nanoparticles were synthesized from HAuCl₄ using an ethanol as a reducing agent. Finally, magnetic nanoparticles were functionalized by hexadecanethiol. The immobilization of biological molecules (trypsin and glucose oxidase) to the thiol-modified and unmodified magnetite–gold nanoparticles surface was tested. The resulting nanoparticles were characterized by infrared spectroscopy, differential scanning calorimetry, Mössbauer spectroscopy and transmission electron microscopy.

Keywords: Magnetite; Magnetite–gold; Thiol modification; Enzyme immobilization

Electrochemical synthesis of Ag nanoparticles supported on glassy carbon electrode by means of p-isopropyl calix[6]arene matrix and its application for electrocatalytic reduction of H₂O₂ by Jahan Bakhsh Raoof; Reza Ojani; Ehteram Hasheminejad; Sahar Rashid-Nadimi (pp. 2788-2795).

► Ag nanoparticles were deposited on the surface of glassy carbon electrode by templating method. ► We used p-isopropyl calix[6]arene as a convenient template for synthesis of silver nanoparticles. ► Ag nanoparticles showed good electrocatalytic activity towards H₂O₂ reduction.The silver nanoparticles were prepared on the glassy carbon (GC) electrode, modified with p-iso propyl calix[6]arene, by preconcentration of silver ions in open circuit potential and followed by electrochemical reduction of silver ions. The stepwise fabrication process of Ag nanoparticles was characterized by scanning electron microscopy and electrochemical impedance spectroscopy. The prepared Ag nanoparticles were deposited with an average size of 70nm and a homogeneous distribution on the surface of electrode. The observed results indicated that the presence of calixarene layer on the electrode surface can control the particle size and prevent the agglomeratione and electrochemical deposition is a promising technique for preparation of nanoparticles due to its easy-to-use procedure and low cost of implementation. Cyclic voltammetry experiments showed that Ag nanoparticles had a good catalytic ability for the reduction of hydrogen peroxide (H₂O₂). The effects of p-isopropyl calix[6]arene concentration, applied potential for reduction of Ag⁺, number of calixarene layers and pH value on the electrocatalytic ability of Ag nanoparticles were investigated. The present modified electrode exhibited a linear range from 5.0×10⁻⁵ to 6.5×10⁻³M and a detection limit 2.7×10⁻⁵M of H₂O₂ (S/N=3) using amperometric method.

Keywords: Silver nanoparticles; p; -Isopropyl calix[6]arene; Hydrogen peroxide; Electrocatalytic reduction; Glassy carbon electrode

Visible-light photocatalytic degradation of methylene blue with laser-induced Ag/ZnO nanoparticles by Thou-Jen Whang; Mu-Tao Hsieh; Huang-Han Chen (pp. 2796-2801).

► The catalytic behavior of Ag/ZnO nanoparticles in the visible-light range is notably improved by the method of laser-induction. ► The maximum efficiency of 92% photodegradation of MB is reached with 2.0wt% Ag/ZnO at pH 11. ► Increasing the content of AgNO₃ in the preparation process will increase the size of Ag particles on ZnO matrix.The preparation of Ag doped ZnO nanoparticles conducted through the method of laser-induction is presented in this work. The Ag/ZnO nanoparticles attained from various weight percentages of added AgNO₃ relative to ZnO were applied under visible-light irradiation for evaluating the heterogeneous photocatalytic degradations of methylene blue (MB) solutions. It was shown that the catalytic behavior of Ag/ZnO nanoparticles in the visible-light range is notably improved through the Ag deposition onto ZnO nanoparticles by the method of laser-induction with a maximum effectiveness of 92% degradation. The properties of the nanoparticles were characterized by the employments of UV–vis spectroscopy (UV–vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and selected-area electron diffraction (SAED).

Keywords: Photocatalysis; Nanoparticles; Zinc oxide; Methylene blue; Laser

Hydrogen peroxide biosensor based on gold nanoparticles/thionine/gold nanoparticles/multi-walled carbon nanotubes–chitosans composite film-modified electrode by Shenfeng Li; Xiaoying Zhu; Wei Zhang; Guoming Xie; Wenli Feng (pp. 2802-2807).

► An electrochemical biosensor for the detection of hydrogen peroxide was fabricated based on the GNPs in situ synthesized. ► Covalent immobilization of HRP on the modified electrode shows good stability. ► The method would be helpful for the further fabrication of biosensors.In this paper, an amperometric electrochemical biosensor for the detection of hydrogen peroxide (H₂O₂), based on gold nanoparticles (GNPs)/thionine (Thi)/GNPs/multi-walled carbon nanotubes (MWCNTs)–chitosans (Chits) composite film was developed. MWCNTs–Chits homogeneous composite was first dispersed in acetic acid solution and then the GNPs were in situ synthesized at the composite. The mixture was dripped on the glassy carbon electrode (GCE) and then the Thi was deposited by electropolymerization by Au–S or Au–N covalent bond effect and electrostatic adsorption effect as an electron transfer mediator. Finally, the mixture of GNPs and horseradish peroxidase (HRP) was assembled onto the modified electrode by covalent bond. The electrochemical behavior of the modified electrode was investigated by scanning electron microscope, cyclic voltammetry and chronoamperometry. This study introduces the in situ-synthesized GNPs on the other surface of the modified materials in H₂O₂ detection. The linear response range of the biosensor to H₂O₂ concentration was from 5×10⁻⁷molL⁻¹ to 1.5×10⁻³molL⁻¹ with a detection limit of 3.75×10⁻⁸molL⁻¹ (based on S/N=3).

Keywords: Hydrogen peroxide; Gold nanoparticles; Carbon nanotubes; Thionine

Thermodynamic evolution of antiphase boundaries in GaP/Si epilayers evidenced by advanced X-ray scattering by W. Guo; A. Bondi; C. Cornet; A. Létoublon; O. Durand; T. Rohel; S. Boyer-Richard; N. Bertru; S. Loualiche; J. Even; A. Le Corre (pp. 2808-2815).

► It is here demonstrated that APD can be detected with simple X-ray lab experimental setups in heterogeneous growth. ► It is shown that statistical information can be extracted to understand how the APD modify thermodynamics of the growth. ► Finally, a link is made between the observed roughness of the samples and APDs and a new growth mechanism is proposed.We have investigated quantitatively anti-phase domains (APD) structural properties in 20nm GaP/Si epilayers grown by molecular beam epitaxy, using fast, robust and non-destructive analysis methods. These analyses, including atomic force microscopy and X-ray diffraction, are applied to samples grown by various molecular beam epitaxy growth modes. Roughness, lateral crystallite size of the epilayer, ratio of antiphase domains and their relationship are discussed. It is shown that both these analysis methods are useful to clarify the physical mechanisms occurring during the heterogeneous growth. Low temperature migration enhanced epitaxy is found to guarantee smoother surface than conventional molecular beam epitaxy. Effect of annealing temperature on antiphase boundaries (APBs) thermodynamics is discussed. The modification of the thermodynamic equilibrium through a thermal activation of APBs motion is expected to play an important role in the dynamic evolution of surfaces during thermal annealing and growth.

Keywords: PACS; 68.55.ag; 61.72.Dd; 68.37.Ps; 78.70.CkX-ray scattering; Growth models; Planar defects; Molecular beam epitaxy; Migration enhanced epitaxy; Semi-conducting III–V materials

Synthesis and characterization of chemically anchored adenosine with PHEMA grafted gold nanoparticles by Long Giang Bach; Md. Rafiqul Islam; Yeon Tae Jeong; Yeong Soon Gal; Kwon Taek Lim (pp. 2816-2822).

Display Omitted► Chemically anchored adenosine with PHEMA grafted gold nanoparticles (Ado- i-PHEMA- g-AuNPs) was synthesized. ► Disulfide-containing PHEMA was initially synthesized by ATRP. ► DT-PHEMA was used for the synthesis of PHEMA- g-AuNPs by a grafting to protocol. ► Boronic acid was used for functionalization of PHEMA- g-AuNPs for covalent immobilization with adenosine. ► Characterization and properties of the Ado- i-PHEMA- g-AuNPs were investigated by FT-IR, XPS, EDX, and UV–visible spectroscopy.The synthesis of chemically anchored adenosine with biocompatible poly(2-hydroxylethyl methacrylate) grafted gold nanoparticles (Ado- i-PHEMA- g-AuNPs) was realized by employing a simple strategy. Disulfide-containing poly(2-hydroxylethyl methacrylate) (DT-PHEMA) was initially synthesized by atom transfer radical polymerization (ATRP). The formation of DT-PHEMA was confirmed by¹H-NMR and FT-IR. The molecular weight and molecular weight distribution were found to be 9.6kg/mol and 1.40 from GPC analysis. DT-PHEMA was subsequently used for the synthesis of PHEMA- g-AuNPs by a grafting to protocol. The grafting of DT-PHEMA on the surface of AuNPs was confirmed by FT-IR, TGA, XPS, and EDX analyses. The particle size of the PHEMA- g-AuNPs was found to be ca. 5.0nm from HR-TEM analysis. Boronic acid was used for functionalization of PHEMA- g-AuNPs, which was then subjected for covalent immobilization with adenosine via strong interaction between free hydroxyl groups of adenosine and boronic acid. Characterization and properties of the Ado- i-PHEMA- g-AuNPs were investigated by taking advantage from FT-IR, XPS, EDX, and UV–visible spectroscopy. The Ado- i-PHEMA- g-AuNPs nanocomposite exhibits a surface plasmon resonance peak at 586nm which is red shifted from AuNPs (521nm), indicating significant changes of surface property upon PHEMA-adenosine immobilization onto the surface of AuNPs.

Keywords: Gold nanoparticles; PHEMA; Polymer brush; ATRP; Adenosine; Covalent immobilization; Boroester linkage

Effect of precursors on structure, optical and electrical properties of chemically deposited nanocrystalline ZnO thin films by C.S. Prajapati; P.P. Sahay (pp. 2823-2828).

► ZnO thin films were grown using different precursors ZnSO₄·7H₂O and Zn(NO₃)₂·6H₂O. ► Lower packing density of grains in the film using Zn(NO₃)₂·6H₂O is observed. ► Film using Zn(NO₃)₂·6H₂O exhibits normal dispersion for wavelength 450–750nm. ► Two energy levels – one deep and one shallow are found in the energy bandgap.Nanocrystalline ZnO thin films were chemically deposited on glass substrates using two different precursors namely, zinc sulphate and zinc nitrate. XRD studies confirm that the films are polycrystalline zinc oxide having hexagonal wurtzite structure with crystallite size in the range 25–33nm. The surface morphology of film prepared using zinc sulphate exhibits agglomeration of small grains throughout the surface with no visible holes or faulty zones, while the film prepared using zinc nitrate shows a porous structure consisting of grains with different sizes separated by empty spaces. The film prepared using zinc sulphate shows higher reflectance due to its larger refractive index which is related to the packing density of grains in the film. Further, the film prepared using zinc sulphate is found to have normal dispersion for the wavelength range 550–750nm, whereas the film prepared using zinc nitrate has normal dispersion for the wavelength range 450–750nm. The direct optical band gaps in the two films are estimated to be 3.01eV and 3.00eV, respectively. The change in film resistance with temperature has been explained on the basis of two competing processes, viz. thermal excitation of electrons and atmospheric oxygen adsorption, occurring simultaneously. The activation energies of the films in two different regions indicate the presence of two energy levels – one deep and one shallow near the bottom of the conduction band in the bandgap.

Keywords: Zinc oxide; Nanocrystalline thin films; Structural properties; Optical Properties; Activation energy

Thermal radiative properties of carbon materials under high temperature and vacuum ultra-violet (VUV) radiation for the heat shield of the Solar Probe Plus mission by M. Balat-Pichelin; J. Eck; J.L. Sans (pp. 2829-2835).

► We measure the evolution of the thermal radiative properties of carbon materials at high temperature and also with adding VUV radiation. ► VUV radiation modifies the microstructure and acts on the thermal radiative properties. ► A mean value of the α/ ɛ ratio of 1.14 can be retained for C/C composites for the Solar Probe Plus mission.The Solar Probe Plus (SP+) mission will approach the Sun as close as 9.5 solar radii in order to understand the origin of the solar corona heating and the acceleration of the solar wind. Submitted to such extreme environmental conditions, a thermal protection system is considered to protect the payload of the SP+ spacecraft. Carbon-based materials are good candidate to fulfill this role and critical point remains the equilibrium temperature reached at perihelion by the heat shield. In this paper, experimental results obtained for the solar absorptivity α, the total hemispherical emissivity ɛ and its ratio α/ ɛ, conditioning the equilibrium temperature of the thermal protection system, are presented for different kinds of carbon materials heated at high temperatures with or without vacuum-UV (100< λ<200nm) radiation. The synergistic effect of ion bombardment is also presented for one kind of material.

Keywords: Thermal radiative properties; Carbon material; High temperature; VUV radiation; Ion etching

Functionalization of vertically aligned carbon nanotubes with polystyrene via surface initiated reversible addition fragmentation chain transfer polymerization by Thomas Macdonald; Christopher T. Gibson; Kristina Constantopoulos; Joseph G. Shapter; Amanda V. Ellis (pp. 2836-2843).

► We demonstrate successful chemical attachment of acid treated carbon nanotubes vertically on a silicon substrate. ► We derivatized the sidewall functionalities of the vertically aligned carbon nanotubes with chain transfer agents for reversible addition fragmentation chain transfer (RAFT) in situ on the silicon substrate. ► Raman and atomic force microscopies showed successful modification of the substrates with polystyrene after in situ RAFT polymerization.Here we demonstrate the covalent attachment of vertically aligned (VA) acid treated single-walled carbon nanotubes (SWCNTs) onto a silicon substrate via dicyclohexylcarbodiimide (DCC) coupling chemistry. Subsequently, the pendant carboxyl moieties on the sidewalls of the VA-SWCNTs were derivatized to acyl chlorides, and then finally to bis(dithioester) moieties using a magnesium chloride dithiobenzoate salt. The bis(dithioester) moieties were then successfully shown to act as a chain transfer agent (CTA) in the reversible addition fragmentation chain transfer (RAFT) polymerization of styrene in a surface initiated “grafting-from” process from the VA-SWCNT surface. Atomic force microscopy (AFM) verified vertical alignment of the SWCNTs and the maintenance thereof throughout the synthesis process. Finally, Raman scattering spectroscopy and AFM confirmed polystyrene functionalization.

Keywords: Vertically aligned carbon nanotubes; Bis(dithioester); Reversible addition fragmentation chain transfer (RAFT); Polystyrene

Towards anode with low indium content as effective anode in organic solar cells by S. Touihri; L. Cattin; D-T. Nguyen; M. Morsli; G. Louarn; A. Bouteville; V.Froger; J.C. Bernède (pp. 2844-2849).

► The manuscript is dedicated to the realization of anode with low indium content. ► We show that a very thin In₂O₃ film deposited onto another transparent conductive oxide (TCO=ZnO, SnO₂) allows to improve the contact between the TCO and the organic material. ► Optima results are achieved when a thin MoO₃ thin film is added to these bilayer structures.In₂O₃ thin films (100nm thick) have been deposited by reactive evaporation of indium, in an oxygen partial atmosphere. Conductive ( σ=3.5×10³S/cm) and transparent films are obtained using the following experimental conditions: oxygen partial pressure=1×10⁻¹Pa, substrate temperature=300°C and deposition rate=0.02nm/s. Layers of this In₂O₃ thick of 5nm have been introduced in AZO/In₂O₃ and FTO/In₂O₃ multilayer anode structures. The performances of organic photovoltaic cells, based on the couple CuPc/C₆₀, are studied using the anode as parameter. In addition to these bilayers, other structures have been used as anode: AZO, FTO, AZO/In₂O₃/MoO₃, FTO/In₂O₃/MoO₃ and FTO/MoO₃. It is shown that the use of the In₂O₃ film in the bilayer structures improves significantly the cell performances. However the open circuit voltage is quite small while better efficiencies are achieved when MoO₃ is present. These results are discussed in the light of surface roughness and surface work function of the different anodes.

Keywords: Organic solar cell; Reactive evaporation; In; ₂; O; ₃; Surface roughness; Surface work function

Surface modification of hydroxyapatite nanoparticles by poly(l-phenylalanine) via ROP ofl-phenylalanine N-carboxyanhydride (Pha-NCA) by Yanfeng Dai; Min Xu; Junchao Wei; Haobin Zhang; Yiwang Chen (pp. 2850-2855).

► The surface of hydroxyapatite nanoparticles were modified by poly(l-phenylalanine)(PPha) via the ring opening polymerization method. ► PPha chains on the surface of HA could main its colloid stability in organic solvent and prevent the aggregation of HA nanoparticles. ► The biocompatibility of PPha modified HA was good, demonstrating its potential application in bone tissue engineering.The surface of hydroxyapatite nanoparticles was modified by poly(l-phenylalanine) via the ring opening polymerization (ROP) ofl-phenylalanine N-carboxyanhydride. The preparation procedure was monitored by Fourier transform infrared spectroscopy (FTIR), and the modified hydroxyapatite was characterized by thermal gravimetric analysis (TGA) and X-ray diffraction (XRD). The results showed that the surface grafting amounts of poly(l-phenylalanine) on HA ranging from 20.26% to 38.92% can be achieved by tuning the reaction condition. The XRD patterns demonstrated that the crystalline structure of the modified hydroxyapatite was nearly the same with that of HA, implying that the ROP was an efficient surface modification method. The MTT assay proved that the biocompatibility of modified HA was very good, which showed the potential application of modified HA in bone tissue engineering.

Keywords: Hydroxyapatite; Surface modification; Ring opening polymerization; Bone tissue engineering

Facile surface glycosylation of PVDF microporous membrane via direct surface-initiated AGET ATRP and improvement of antifouling property and biocompatibility by Jing Yuan; Jian-qiang Meng; Yin-lin Kang; Qi-yun Du; Yu-feng Zhang (pp. 2856-2863).

► A facile method was developed for surface glycosylation of the PVDF membrane. ► A glycopolymer PGAMA was grafted onto the membrane surface via AGET ATRP initiated directly from the membrane surface. ► The PGAMA grafts obviously improved the membrane surface hydrophilicity. ► The protein adsorption of the glycosylated membrane can be controlled at 20% of the pristine membrane. ► The platelets adhesion of the glycosylated membrane was greatly decreased.This paper describes a facile and novel approach for the surface glycosylation of poly(vinylidene difluoride) (PVDF) microporous membrane. A glycopolymer poly(d-gluconamidoethyl methacrylate) (PGAMA) was tethered onto the membrane surface via activators generated by electron transfer atom transfer radical polymerization (AGET ATRP) directly initiated from the PVDF surface. Chemical changes of membrane surface were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). It was revealed that PGAMA was successfully grafted onto the membrane surface and its grafting density can be modulated in a wide range up to 2.4μmol/cm². The effects of glycosylation on membrane morphology, flux and surface hydrophilicity were investigated. Field emission scanning electron microscopy (FESEM) results indicated shrinkage of the surface pore diameters and the growth of the glycopolymer layer on the membrane surface. The static water contact angle (WCA) of the membrane surface decreased from 110° to 30.4° with the increase of grafting density, indicating that the PGAMA grafts dramatically improved the surface hydrophilicity. The protein adsorption and platelets adhesion experiments indicated that the grafted PGAMA could effectively improve the membrane antifouling property and biocompatibility.

Keywords: AGET ATRP; PVDF membrane; Glycosylation; Antifouling property; Biocompatibility

Deposition of titanium nitride (TiN) on Co–Cr and their potential application as vascular stent by Vuong-Hung Pham; Shin-Hee Jun; Hyoun-Ee Kim; Young-Hag Koh (pp. 2864-2868).

► TiN film was deposited on a Co–Cr substrate by reactive DC sputtering. ► The TiN film improved the mechanical properties of the Co–Cr significantly. ► The film also enhanced the activity of endothelial cells on the substrate.This study reports the effect of a TiN film on the mechanical properties and endothelial compatibility of a Co–Cr substrate. A dense, columnar TiN film with a preferential orientation of the (111) plane was deposited successfully on a Co–Cr substrate by reactive DC sputtering, particularly by applying a negative substrate bias during deposition. Good adhesion between the TiN film and Co–Cr substrate was achieved using a thin Ti film as an intermediate layer. The TiN film improved the mechanical properties of the Co–Cr significantly, such as the surface hardness and elastic modulus. In addition, the attachment and proliferation of endothelial cells were enhanced remarkably, which was attributed mainly to the favorable absorption of proteins on a biocompatible TiN surface.

Keywords: Biomaterials; Metals and alloys; Sputtering; Biocompatibility; Deposition; Endothelial cell

Characterization of oxide structures on stainless steel sternal wires by electrochemical reduction by Yea-Yang Su; Chun-Che Shih; Lung-Ching Chen; Chun-Ming Shih; Shing-Jong Lin (pp. 2869-2875).

► Potential variation is the basis for the cathodic reduction of oxide films. ► Distinguished potentials are the characters of each oxide species for polycrystalline oxide and transition potential is for amorphous oxide. ► Cathodic reduction has the capability to differentiate oxide structures.Different oxide structures can be formed on passive stainless steel sternal wires by various surface modifications. Oxide structure has a significant influence on the efficacy and biocompatibility of the medical devices. In this study, cathodic reduction was used to distinguish the oxide structures on 316L stainless steel sternal wires in a buffered phosphate electrolyte. TEM, Auger depth profile, XPS, and SEM were applied to examine the oxide structures. Interfacial resistance was measured using electrochemical impedance spectroscopy. Results indicate that cathodic reduction profiles have the capability to identify oxide structures on the passivated medical devices.

Keywords: Stainless steel; Surface modification; Surface analysis

Preparation of kapok–polyacrylonitrile core–shell composite microtube and its application as gold nanoparticles carrier by Haosen Fan; Xiaolan Yu; Yuhua Long; Xiaoyan Zhang; Haifan Xiang; Chunting Duan; Ning Zhao; Xiaoli Zhang; Jian Xu (pp. 2876-2882).

► A new catalyst support kapok–PAN composite microtube was fabricated based on the natural kapok fiber by a cetyltrimethylammonium bromide (CTAB) assisted self-assembly method. ► Au nanoparticles (NPs) were immobilized on the surface of kapok–PAN microtubes via in situ reduction of chloroauric acid (HAuCl₄) by sodium borohydride (NaBH₄). ► The obtained kapok–PAN–Au composites exhibited excellent catalytic activity and reusability as demonstrated via the reduction of 4-nitrophenol to 4-aminophenol by NaBH₄.In this article, a new catalyst carrier kapok–polyacrylonitrile (PAN) composite microtube was fabricated based on the natural kapok fiber. Kapok-PAN core–shell composite microtubes were prepared by a cetyltrimethylammonium bromide (CTAB) assisted self-assembly method. The formation mechanism was proposed and the influence of the concentration of acrylonitrile (AN) monomer and CTAB on the morphology of kapok–PAN was investigated. The hydrophilicity and specific surface area of kapok microtubes were improved because of the outside PAN coating constructed by the PAN nanoparticles aggregation. Gold nanoparticles (Au NPs) were immobilized on the surface of kapok–PAN microtubes via in situ reduction of chloroauric acid (HAuCl₄) by sodium borohydride (NaBH₄). The obtained Au NPs with mean diameter of 3.1nm were well dispersed without any aggregation. In addition, kapok–PAN–Au composites exhibited excellent catalytic activity and could be recovered easily without apparent decrease of activity, as demonstrated via the reduction of 4-nitrophenol to 4-aminophenol by NaBH₄. The kapok–PAN composite microtubes may be one of the promising supporting materials in developing low-cost, high-efficiency catalyst carriers for metal NPs.

Keywords: Kapok; Polyacrylonitrile (PAN); Gold nanoparticles; Microtube; Catalyst carriers

Influence of Dy content on the structure and giant magnetoresistance of Dy_x(Co₄₀Ag₆₀)100−_x granular films by Cheng Gang; Wu Xiaofei; Chen Wei; Geng Shengdong; Li Lin; Gu Zhengfei (pp. 2883-2885).

► The first study to effect Dy element on structure and magnetic properties of CoAg films. ► The first study showing the average size of magnetic particles as a parameter of Dy content. ► For relatively low addition Dy to CoAg granular films, Dy can enhance GMR value.Dy_x(Co₄₀Ag₆₀)100−_x ( x=0, 0.7, 1.4, 2.1, 2.8, 3.5) granular films have been prepared by DC magneto controlled sputtering method. The XRD data indicated that Dy element restrained the (111) plane preferential orientation. Magnetic measurements indicated that the average size of magnetic particles increased with the increasing in Dy content. For relatively low addition Dy to CoAg granular films, Dy element can enhance GMR value as a maximum value of the GMR value ∼−18.1% at x=0.7.

Keywords: Giant magnetoresistance; Granular films; Magnetic particle

Pulsed electrodeposition of Co–W amorphous and crystalline coatings by Mrinalini Mulukutla; Vamsi Karthik Kommineni; Sandip P. Harimkar (pp. 2886-2893).

► Amorphous and crystalline Co–W coatings using pulsed electrodeposition. ► The Co–W coatings exhibited better wear and corrosion resistance than steel substrate. ► Nanostructured Co–W coatings with microhardness in the range of ∼575–725HV were formed at optimized pulse processing conditions.Replacement of hard chromium plating has been of particular interest to many industrial applications, including automotive, aircraft, and machinery parts that require high hardness and wear/corrosion resistance. Co–W alloy coatings, owing to their eco-friendly processing and high hardness/wear resistance, are promising for electrolytic chromium replacement. In the present study, pulsed electrodeposition of amorphous and crystalline Co–W coating is reported. Systematic investigations on the effect of pulse duty cycle and pulse frequency on development of surface microstructure, phases, composition, surface roughness, and micro-hardness are presented. Furthermore, detailed analysis of micro-/nano-mechanical (using ball-on-disc wear tester and nanoindentor) and corrosion (using potentiodynamic polarization method) behavior of optimized Co–W coatings is presented.

Keywords: Electrodeposition; Amorphous coatings; X-ray diffraction; Microhardness; Wear resistance

The impact of substrate properties and thermal annealing on tantalum nitride thin films by M. Grosser; M. Münch; H. Seidel; C. Bienert; A. Roosen; U. Schmid (pp. 2894-2900).

► Tantalum nitrides were deposited by magnetron sputtering on SiO₂, Si and LTCC-UEN. ► The study focuses on three different TaN_x and the influence of annealing on them. ► Different facts to resistivity, surface morphology, near surface composition and phase stability are reported. ► The surface morphology undergoes strong changes with temperature. ► Two of three TaN_x show superior phase stability.In this study film properties of sputter-deposited tantalum nitride (TaN_x) thin layers are investigated focusing on the impact of substrate properties, varying nitrogen content for film synthetization as well as post-deposition annealings in the temperature range up to 500°C. For comparison, these investigations are done on low temperature co-fired ceramics and on silicon based substrates whereas the latter approach ensures defined and well-known surface properties. Furthermore, results on the phase evolution with high temperature annealings are presented showing a transformation of Ta₄N to Ta₂N in the temperature range between 350°C and 500°C. With increasing nitrogen content (i.e. nitrogen flow during film deposition) in the TaN_x layers the topography shows first an increase in surface roughness, next a range where a smoothing of the surface characteristics is observed, and finally buckling and the existence of grain agglomerates. All these analyses are further evaluated with electrical measurements on the film resistivity and on the oxidation behaviour to gain deeper insight into material parameters relevant for micromachined devices which are operated under harsh environmental conditions.

Keywords: Tantalum nitride; Thin films magnetron sputtering; Microstructure; Thermal annealing; LTCC; SiO; ₂; Resistivity

The effect of SiO₂-doped boron nitride multiple coatings on mechanical properties of quartz fibers by Yu Zheng; Shubin Wang (pp. 2901-2905).

► A new kind of fiber coatings: SiO₂/BN multiple coatings are prepared. ► Effect of SiO₂/BN multiple coatings on quartz fibers strength is researched. ► The SiO₂ powders suppress the crystallization of the quartz fiber.SiO₂-doped boron nitride multiple coatings (SiO₂/BN multiple coatings) were prepared on quartz fibers surface at 700°C. Single fiber tensile test was employed to evaluate fiber tensile strength; Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were employed to evaluate morphology and structure of the fibers. Fiber tensile test results indicated that the strength of quartz fibers with SiO₂/BN multiple coatings was about twice of the fibers with BN coatings and original fibers which were heated at 700°C for 10h. The SiO₂/BN multiple coatings would provide compressive stress on quartz fibers, which would help to seal the defects on fiber surface. Furthermore, TEM images showed that the nano-SiO₂ powders crystallized in advance of quartz fibers, which would suppress crystallization of quartz fibers and reduce damage from crystallization. Thus, nano-SiO₂ powders would help to keep mechanical properties of quartz fibers.

Keywords: SiO; ₂; /BN multiple coatings; Quartz fibers; Crystallization

The ferromagnetic properties of Ge magnetic quantum dots doped with Mn by Xiying Ma; Caoxin Lou (pp. 2906-2909).

► Monodispersed and perfect Ge:Mn magnetic quantum dots were grown from a GeH₄/Ar mixed gas, then doped with Mn. ► The as-grown and annealed QDs showed widely opened hysteresis loops and large remnant magnetizations M_r. ► The QDs show an average value of the moment per Mn atom to be as high as 2.36μ_B at room temperature. ► The colossal moment is attributed to an effective RKKY exchange coupling interaction between the Mn ions mediated by holes.We present a synthesis of Ge:Mn magnetic quantum dots (QDs) and an evaluation of their ferromagnetic properties. The QDs were grown from a GeH₄/Ar mixed gas under constant flow conditions at 400°C by means of a plasma-enhanced chemical vapor deposition (PECVD) process, then doped with Mn by a magnetic sputtering technique and annealed at 600°C. The QDs, with a composition of Ge_0.88Mn_0.12 according to their energy spectrum, showed widely opened hysteresis loops, with large remnant magnetizations M_r of 0.14×10⁻⁴ and 0.25×10⁻⁴emu/g for the as-grown and annealed samples, respectively. Moreover, the average value of the moment per Mn atom was found to be as high as 2.36μ_B at room temperature, showing that the Ge1−_xMn_x QDs constitute an intrinsic diluted magnetic semiconductor. The unprecedented colossal moment is attributed to an effective RKKY exchange coupling interaction between the Mn ions mediated by holes.

Keywords: PACS; 42.70.Qs; 42.25B; 78.20.P; 78.55EGe:Mn QDs; Ferromagnetic properties; Magnetic moment

Ion trajectories and shadow effects in mesh-assisted plasma immersion ion implantation of insulator by Yongxian Huang; Xiubo Tian; Shixiong Lv; Shiqin Yang; R.K.Y. Fu; Paul K. Chu; Jinsong Leng; Yao Li (pp. 2910-2913).

► A PIC model considering SEE with ion instantaneous incident energy is developed. ► Ions trajectories under the assisted mesh are specifically described. ► Mesh-assisted PIII can provide better implantation dynamics for insulators. ► An aluminum plasma implanted coating is achieved on 5mm thick polymer.A two-dimensional particle-in-cell (PIC) model considering secondary electron emission (SEE) as a function of ion instantaneous incident energy is developed for describing ion trajectories and shadow effects in mesh-assisted plasma immersion ion implantation (PIII) of insulator. The simulation results indicate that mesh-assisted PIII can improve the equivalent surface potential, suppress the emission of secondary electrons and provide better implantation dynamics for ions implantation on insulator. On 5mm thick polymer substrate, an aluminum plasma implanted coating is achieved with excellent adhesion strength by mesh-assisted PIII with 10mm mesh height. Consistent results are obtained from experiments and numerical simulation disclosing that shallow effects can be eliminated, and ions incident energy is enhanced.

Keywords: Ion trajectory; Shadow effect; Mesh-assisted plasma immersion ion implantation; Insulator; Particle-in-cell

Generation of cavities in silicon wafers by laser ablation using silicon nitride as sacrificial layer by B. Lerner; M.S. Perez; C. Toro; C. Lasorsa; C.A. Rinaldi; A. Boselli; A. Lamagna (pp. 2914-2919).

Display Omitted► Laser ablation on silicon wafers with a sacrificial layer was performed. ► An alternative to the traditional michomachining method was introduced. ► The optimal fluence able to remove the sacrificial layer was found. ► When increasing the pulses number, the pyramidal cavity's capacity is greater.Throughout this investigation, experiments on laser ablation with silicon (Si) wafers have been performed using silicon nitride (Si₃N₄) as a sacrificial layer to find the optimal fluence capable of removing the Si₃N₄, which allows the subsequent anisotropic etching in Si with potassium hydroxide. As a result, an alternative to the traditional micromachining techniques that require more steps and processing times has been introduced. The effect of the pulse numbers on Si wafers has been studied and it has been observed that when increasing the pulse numbers at the same fluence, the capacity of the pyramidal cavity formed was greater than using only one pulse at higher fluences.Microcavities were performed with a floating Si₃N₄ layer. This happens to be very useful for the development of drug delivery systems and the manufacture of microarrays. Microcavities were also used as masters for the fabrication of microionizers in polydimethyl siloxane (PDMS).

Keywords: Laser ablation; Silicon wet etching; Si; ₃; N; ₄; sacrificial layer; Microcavities

Conductive-probe AFM characterization of graphene sheets bonded to gold surfaces by Fanny Hauquier; David Alamarguy; Pascal Viel; Sophie Noël; Arianna Filoramo; Vincent Huc; Frédéric Houzé; Serge Palacin (pp. 2920-2926).

► Graphene sheets are bonded to polyaminophenylene films grafted on gold substrates. ► CP-AFM is a powerful tool to discern different numbers of stacked graphene sheets. ► Friction is reduced on graphene sheets in comparison with the organic coating. ► Current–voltage curves display characteristics of metal–molecule–metal junctions.Conducting probe atomic force microscopy (CP-AFM) has been used to perform mechanical and electrical experiments on graphene layers bonded to polyaminophenylene (PAP) films grafted on gold substrates. This technique is a new approach for the characterization of graphene sheets and represents a complementary tool to Raman spectroscopy. The combination of friction and electrical imaging reveals that different stacked graphene sheets have been successfully distinguished from each other and from the underlying PAP films. Lateral force microscopy has shown that the friction is greatly reduced on graphene sheets in comparison with the organic coating. The electrical resistance images show very different local conduction properties which can be linked to the number of underlying graphene sheets. The resistance decreases very slowly when the normal load increases. Current–voltage curves display characteristics of metal–molecule–metal junctions.

Keywords: Graphene; AFM; Friction; Electrical properties; Raman

Tailoring the in-plane epitaxial relationship of InN films on (111)SrTiO₃ substrates by substrate pretreatment by C.H. Jia; Y.H. Chen; B. Zhang; X.L. Liu; S.Y. Yang; W.F. Zhang; Z.G. Wang (pp. 2927-2930).

► We grow InN films on as-received and water-immersed (111)SrTiO₃ substrates by MOCVD. ► The epitaxial relationships between InN and STO are investigated by XRD. ► Two kinds of in-plane alignment with a 30° rotation have been observed. ► The in-plane orientation is strongly dependent on substrate pretreatment. ► Different terminated surface is responsible for the change in epitaxial relationship.Wurtzite InN films of c-axis orientation have been grown on as-received and water-immersed (111)SrTiO₃ (STO) substrates by metal–organic chemical vapor deposition. The epitaxial relationships between InN films and STO substrates are investigated by X-ray diffraction. Two kinds of in-plane alignment of[112¯0]InN∥[11¯0]STO and[11¯00]InN∥[11¯0]STO with a 30° rotation relative to each other have been realized on as-received and water-immersed (111)STO substrates, respectively. The in-plane orientation of InN relative to STO is strongly dependent on substrate pretreatment, but not sensitive to growth temperature and trimethylindium flow rates. The difference in terminated surfaces of as-received and water-immersed STO substrates are postulated to be responsible for the change in epitaxial relationships. Compared with each other, the in-plane epitaxial relationships of[11¯00]InN∥[11¯0]STO and[112¯0]InN∥[11¯0]STO are respectively energetically preferred due to a higher bonded density and thus a lower interface energy on SrO₃- and Ti-terminated STO substrates.

Keywords: In-plane orientation; InN; SrTiO; ₃; MOCVD

Surface modification of diamond-like carbon films to graphene under low energy ion beam irradiation by S.S. Tinchev (pp. 2931-2934).

► Modification of the surface of diamond-like carbon to graphene. ► Modification by low-energy Ar ion irradiation. ► Point defect creation and enhanced diffusion caused by the ion bombardment enable growth of nano-sized graphene particles at low temperature.Low-energy ion beam modification was proposed to create graphene on the top of the insulated diamond-like carbon (DLC) films. In such low-temperature process the surface of the amorphous carbon could crystallize to graphene as a result of point defect creation and enhanced diffusion caused by the ion bombardment. In the experiment 130eV argon ion irradiation was used. After the modification the resistivity of the sample surface drops and the underlying DLC remained highly insulating. Raman spectra of the samples measured at 633nm showed partial crystallization and were similar to the spectra of defected graphene. This result is very encouraging and we hope that by improving this technology it will be possible to fabricate defect-free graphene, which can be used in electronics without transfer to other substrates.

Keywords: Diamond-like carbon; Graphene; Ion beam modification

A novel method for the preparation of Cu/Al₂O₃ nanocomposite by Yueli Wen; Wei Huang; Bin Wang (pp. 2935-2938).

► Synthesis method is novel, simple and low cost compared to conventional method. ► Two phases of the Cu/Al₂O₃ nanocomposite disperse homogenously. ► The Cu/Al₂O₃ nanocomposites self-assemble into columnar structure. ► Plausible mechanism for this reaction is proposed.Well-dispersed Cu/Al₂O₃ nanocomposite was prepared by a novel chemical reduction method using paraffin as reductant and solvent. The product was characterized by X-ray diffraction measurements (XRD), transmission electron microscope (TEM), energy dispersive analysis of X-ray (EDS), X-ray photoelectron spectra (XPS), and X-ray Auger electron spectroscopy (XAES). TEM images show the Cu/Al₂O₃ nanocomposite particles are spherical with an average size of 20nm, and self-assemble into columnar structure.

Keywords: Cu/Al; ₂; O; ₃; nanocomposite; Nanoparticle; Self-assemble; Columnar nanostructure

Composite coating prepared by micro-arc oxidation followed by sol–gel process and in vitro degradation properties by Yi Zhang; Kuifeng Bai; Zhenya Fu; Caili Zhang; Huan Zhou; Liguo Wang; Shijie Zhu; Shaokang Guan; Dongsheng Li; Junhua Hu (pp. 2939-2943).

► We prepared a TiO₂/MAO composite coating on home-developed Mg alloy. ► The porous MAO layer was sealed by subsequently coated TiO₂ layer. ► The anticorrosion properties were improved obviously by composite coatings in term of corrosion potential and corrosion current density.A Mg phosphate coating was prepared on home-developed Mg–Zn–Ca alloy to improve its anticorrosion performance in simulated body fluid (SBF, Kokubo solution). The coating was prepared by micro-arc oxidation (MAO) method at the working voltage of 120–140V. Evident improvement of anticorrosion was obtained even through the surface was porous. To further diminish the contact with SBF, a TiO₂ layer was coated on the porous MAO layer by sol–gel dip coating followed by an annealing treatment. The coatings were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS). The electrochemical performance of the MAO and TiO₂/MAO coated alloys was evaluated by anodic polarization measurements. The pores on Mg phosphate layer provided accommodation sites for the subsequent TiO₂ sol–gel coating which sealed the pores and hence significantly enhanced the anticorrosion while single MAO coating only improve anticorrosion within a limited range. The present result indicates that fabrication of composite coatings is a significant strategy to improve the corrosion resistance of Mg–Zn–Ca alloy and other alloys, thus enhancing the potential of using Mg alloys as bio-implants.

Keywords: Mg–Zn–Ca; Mg phosphate; TiO; ₂; Corrosion resistance

Room temperature oxidation of magnetron sputtered Si–C–N films by E. Hüger; D. Gao; A. Markwitz; U. Geckle; M. Bruns; H. Schmidt (pp. 2944-2947).

► We demonstrated that room temperature oxidation takes place in magnetron sputtered amorphous silicon carbonitride films of composition Si₁₉C₂₁N₆₀. ► The oxide layer growth kinetics was determined by infra-red spectroscopy and X-ray reflectometry. ► A linear growth law is found which can be explained by the presence of nano-pores in the oxide layer. ► The existence of nano-pores is indicated by atomic force microscopy.We produced nitrogen- and carbon-rich amorphous Si–C–N thin films of chemical composition Si₁₉C₂₁N₆₀ by reactive magnetron co-sputtering on Si substrates and investigated their thermal stability in air at room temperature. Infra-red spectroscopy and X-ray reflectometry measurements demonstrated that the films show a pronounced oxidation in air already at room temperature, a behaviour which was previously not found for other compositions. A linear growth law is observed, which can be explained by a nano-porous structure of the formed SiO₂ oxide scale. High-resolution atomic force microscopy indicated the presence of such a nano-porous structure with a pore diameter of 5nm and a diameter of the pore walls of 3nm.

Keywords: Silicon carbonitrides; Oxidation, X-ray reflectivity; Infra-red spectroscopy

Detector surface preparation of Cd_0.9Zn_0.1Te for electrode patterning by J. Crocco; Q. Zheng; H. Bensalah; E. Dieguez (pp. 2948-2952).

► The results presented here have been obtained using novel approaches for removing surface contamination. ► Results for polishing and cleaning using capillary force templates are presented. ► Detailed procedure for preparing surface of CZT for electrode deposition described. ► Darkfield microscopy mapping of surface before and after cleaning presented. ► Using the capillary for templates, the wax bonding step may be eliminated for fixing wafer to optical flat.One of the challenges in fabricating radiation detectors based on CZT is the surface engineering for electrode deposition. Prior to electrode deposition, it is important the removal of residual contamination from the surface. Using abrasive slurries with micron and sub-micron particulates results in particle adherence to the surface, as can be readily observed using Darkfield microscopy. In addition, the wax bonding of wafers to glass plates for polishing results in further contamination as a result of solvent cleaning and inefficient wax removal in the de-bonding process.In this work, wafer mounting holders which rely upon the surface tension of a liquid are used to replace wax bonding. Using this method, detector surfaces can be prepared without the need for wax bonding and removal. As a result, the pristine nature of the surface is maintained.

Keywords: Gradient freeze technique; Cadmium compounds

The structure and electrical properties of HfTaON high- k films prepared by DIBSD by Tao Yu; Chenggang Jin; Xumin Yang; Yaojun Dong; Haiyan Zhang; Lanjian Zhuge; Xumei Wu; Zhaofeng Wu (pp. 2953-2958).

► High-quality HfTaON MIS capacitors fabricated by a novel method—DIBSD. ► As compared with other high- k materials, HfTaON has a higher dielectric constant and lower leakage current. ► Excellent microstructure, thermal stability and dielectric property can be observed below 1000°C. ► Phase separation is not completely suppressed after 1100°C PDA.We have investigated the microstructure and electrical properties of HfTaON high- k films deposited on n-type Si (100) substrate using a dual ion beam sputtering deposition technique (DIBSD). It is worth noting that HfO₂ begin to precipitate from four-compound HfTaON and crystallize as a monoclinic phase after annealing at 1100°C. From FTIR spectra, one strong absorption peak at 512cm⁻¹, which is characteristic of the HfO₂ monoclinic structure is also observed. The interfacial SiO_x can be formed during the annealing procedure rather than sputtering process, and the increase of atomic percentage of SiO bands and transition from SiO_x ( x<2) to SiO₂ are observed with the increase of annealing temperature. High efficiency HfTaON film prepared by novel DIBSD has a higher dielectric constant of 24 and lower leakage current of 2.28×10⁻⁸A at V_g=( V_fb−1), as compared with that of SiO₂ HfSiON HfTaO films with same thickness.

Keywords: HfTaON; XPS; TEM; FTIR; Crystallization temperature; Electrical characteristic

Encapsulation of Fe₃O₄ magnetic nanoparticles with poly(methyl methacrylate) via surface functionalized thiol-lactam initiated radical polymerization by Long Giang Bach; Md. Rafiqul Islam; Jong Tae Kim; SungYong Seo; Kwon Taek Lim (pp. 2959-2966).

Display Omitted► PMMA grafted MNPs were synthesized by thiol-lactam initiated radical polymerization (TLIRP). ► The surface of MNPs was functionalized by thiol groups using MPTMS. ► The grafting of PMMA on the surface of MNPs was confirmed by spectral analyses. ► Core/shell structured PMMA- g-MNPs nanocomposites was confirmed by HR-TEM. ► The magnetic and dispersibility properties of the MNPs were also investigated.Poly(methyl methacrylate) (PMMA) was grafted onto Fe₃O₄ magnetic nanoparticles (MNPs) by using a thiol-lactam initiated radical polymerization (TLIRP) via grafting from approach. The surface of the MNPs was treated with the (3-mercaptopropyl)trimethoxysilane coupling agent to give thiol functionalized MNPs (MNPs-SH). Subsequently, the polymerization of MMA performed in the presence of the MNPs-SH and butyrolactam efficiently afforded PMMA- g-MNPs. The grafting of PMMA on the surface of the MNPs was investigated by FT-IR,¹H NMR, TGA, XPS, and EDX analyses. The morphology of the core/shell type PMMA- g-MNPs was confirmed by HR-TEM. GPC analysis showed that the molecular weight of PMMA and monomer conversion increased with the reaction time. The amount of the grafted polymer on the surface of the MNPs was found to be ca. 82.5% as estimated from TGA analysis. The MNPs and PMMA- g-MNPs were subjected to magnetic property investigation by SQUID, and the PMMA- g-MNPs showed relatively high saturated magnetization (53.3emu/g) without any remanence or coercivity, which made the nanocomposites easily separable from solid–liquid phases suggesting their superparamagnetic character. The magnetic nanocomposites had an exceptionally good dispersibility in organic solvents as demonstrated by UV–Vis spectroscopy as well as time-dependent digital photographic monitoring.

Keywords: Fe; ₃; O; ₄; magnetic nanoparticles (MNPs); Hybrid nanocomposites; TLIRP; PMMA; Surface initiated polymerization; Grafting from

Sprayed lanthanum doped zinc oxide thin films by Y. Bouznit; Y. Beggah; F. Ynineb (pp. 2967-2971).

► High quality films have been prepared using improved pneumatic spray method. ► Lanthanum doping improve the grain growth rather the crystallites growth. ► ZnO film showed good optic transmission.Lanthanum doped zinc oxide thin films were deposited on soda-lime glass substrates using a pneumatic spray pyrolysis technique. The films were prepared using different lanthanum concentrations at optimum deposition parameters. We studied the variations in structural, morphological and optical properties of the samples due to the change of doping concentration in precursor solutions. X-ray diffraction (XRD) patterns show that pure and La-doped ZnO thin films are highly textured along c-axis perpendicular to the surface of the substrate. Scanning electron micrographs show that surface morphology of ZnO films undergoes a significant change according to lanthanum doping. All films exhibit a transmittance higher than 80% in the visible region.

Keywords: Spray; Zinc oxide; Thin films; Doping; Lanthanum

Superhydrophobic RTV silicone rubber insulator coatings by Seyed Amirhossein Seyedmehdi; Hui Zhang; Jesse Zhu (pp. 2972-2976).

► This study relates to a new type of superhydrophobic RTV silicone rubber coatings for insulators. ► These new coatings demonstrate high contact angles and low sliding angles. ► They passed electrical and mechanical tests. ► This coating can be used in industry to reduce the problem of existing insulator coatings.On wet days, environmental contamination of outdoor insulation surfaces can reduce the reliability of electrical transmission systems and lead to flashover and arcing over the entire insulator. The use of superhydrophobic coatings would resolve this problem due to their self-cleaning effect. Water droplets can pick up dirt particles and remove contamination from the surfaces of insulators. This paper reports on a study to make a superhydrophobic RTV silicone rubber coating that has contact angles of higher than 145° and good UV durability. The Inclined Plane Test, water durability test and adhesion test are presented to show the effectiveness of this coating and the best formulations. The results of tracking and erosion resistance test (Inclined Plane Test) showed that formulations with at least 35wt% ATH can be used for superhydrophobic RTV insulator coatings.

Keywords: RTV silicone rubber coating; Superhydrophobic surface; Nano fluoric particle; Inclined Plane Test; UV durability; Alumina tri-hydrate

Template-based synthesis of Ni nanorods on silicon substrate by Xiaoyun Jin; Yan Hu; Yao Wang; Ruiqi Shen; Yinghua Ye; Lizhi Wu; Shouxu Wang (pp. 2977-2981).

► Large surface area Ni nanorods were fabricated on Ti pre-coated silicon substrate by pulsed electrodeposition. ► Al/Ni heterostructure can be formed by depositing a layer of Al on the Ni nanorods. ► This heterostructure has the potential application as a heat source or energetic material in silicon-based MEMS compatible devices.Free-standing nickel (Ni) nanorods were successfully prepared by pulsed electrodeposition using porous alumina membrane (PAM) on titanium (Ti) pre-coated silicon (Si) substrate. Initially, Si substrate was coated with subsequent layers of Ti (∼200nm) and Al (∼600nm) by sputtering process. The PAM/Ti/Si structure was fabricated by a two-step anodization in 0.3M oxalic acid under a constant voltage of 40V, and then used to grow Ni nanorods by pulsed electrodeposition. Finally, an Al layer was deposited on the Ni nanorods. The relationship between the pore-widening time and the pore diameter of the PAM on Si was also investigated. Field emission scanning electron microscopy (FESEM) was employed to observe the morphology of PAM, Ni nanorods and Al/Ni heterostructure. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to study the morphological and structural properties of Ni nanorods, respectively. Also, the compositional properties of the samples were characterized by energy dispersive X-ray spectra (EDS). The pore diameter and the pore length of the PAM were approximately 54.2±12.2nm and 800nm, respectively. The Ni nanorods stand perpendicularly on the substrate, whose diameter and length were similar to the PAM. The Ni nanorods give an XRD pattern of face-centered cubic crystal structure. Ni nanorods with deposited a layer of Al have the potential application of a heat source or energetic material in the silicon-based micro-electromechanical systems (MEMS) compatible device.

Keywords: Nickel nanorods; Electrodeposition; Anodization; Porous alumina membrane; MEMS

Growth of single-walled carbon nanotubes from hot-implantation-formed catalytic Fe nanoparticles assisted by microwave plasma by Yasushi Hoshino; Hiroki Arima; Yasunao Saito; Jyoji Nakata (pp. 2982-2988).

Display Omitted► We investigate growth of single-walled carbon nanotubes from hot-implantation-formed catalysts. ► Carbon nanotubes are grown by microwave-plasma-enhanced chemical vapor deposition. ► We characterize the nanoparticles by cross-sectional TEM images. ► Raman spectra show the growth of single-walled carbon nanotubes. ► We investigate the growth process of the CNTs during microwave-plasma-enhanced chemical vapor deposition.We have investigated a fabrication of carbon nanotubes (CNTs) from Fe nano-size clusters formed near the surface of the thermally grown SiO₂ layer on the Si substrates using Fe⁺ implantation at the substrate temperatures of 600 and 1000°C. In the present study, we have found that the cluster size formed by the 600°C-implantation is significantly uniform with the mean diameter and standard deviation of 2.6 and 0.6nm, respectively. In contrast, the diameter distribution for the 1000°C-implanted sample was slightly deviated, taking the values of 3–13nm. The cluster size mainly depends on the substrate temperature during the implantation. We have confirmed single-walled CNTs grown from the Fe nanoparticles formed near the surface region in the SiO₂ layer, via clearly observed peaks for the radial-breathing-mode in Raman spectra. We have also investigated the growth mechanism of the CNTs in terms of the plasma and surface interactions during microwave-plasma-enhanced chemical vapor deposition (MPCVD). It should be emphasized that the ion implantation technique combined with the MPCVD method is a powerful tool for in situ growth of SWCNT directly on a SiO₂ layer or Si substrate.

Keywords: Carbon; Nanostructure; Ion implantation; Microwave plasma; Chemical vapor deposition

Influence of Si–C bond density on the properties of a-Si1−_xC_x thin films by Habibuddin Shaik; K.H. Thulasi Raman; G. Mohan Rao (pp. 2989-2996).

► Higher substrate temperature decreases bandgap but favors Si–C bonding. ► The influence of C concentration is dominant on the bandgap than Si–C bonds. ► Low target powers were favorable for Si–C bonding. ► Influence of Si–C bond density on the behavior of the deposited films.Amorphous silicon carbide (a-Si1−_xC_x) films were deposited on silicon (100) and quartz substrates by pulsed DC reactive magnetron sputtering of silicon in methane (CH₄)–Argon (Ar) atmosphere. The influence of substrate temperature and target power on the composition, carbon bonding configuration, band gap, refractive index and hardness of a-SiC films has been investigated. Increase in substrate temperature results in slightly decreasing the carbon concentration in the films but favors silicon–carbon (Si–C) bonding. Also lower target powers were favorable towards Si–C bonding. X-ray photoelectron spectroscopy (XPS) results agree with the Fourier Transform Infrared (FTIR), UV–vis spectroscopy results. Increase in substrate temperature resulted in increased hardness of the thin films from 13 to 17GPa and the corresponding bandgap varied from 2.1 to 1.8eV.

Keywords: a-SiC; Si–C bonding; C–C bonding; Pulsed DC; XPS; Infrared spectroscopy; Hardness

CuO nanoparticles: Synthesis, characterization, optical properties and interaction with amino acids by A. El-Trass; H. ElShamy; I. El-Mehasseb; M. El-Kemary (pp. 2997-3001).

► Cupric oxide (CuO) nanoparticles with an average size of 6nm have been successfully prepared. ► Picosecond fluorescence measurements of the nanoparticles suggest bi-exponential function. ► Zeta potential of CuO aqueous suspension is negative. ► The results should be useful for understanding the mode of the interaction with biological systems.Cupric oxide (CuO) nanoparticles with an average size of 6nm have been successfully prepared by an alcothermal method. The prepared CuO nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) and UV–visible absorption spectroscopy. A strong sharp emission under UV excitation is reported from the prepared CuO nanoparticles. The results show that the CuO nanoparticles have high dispersion and narrow size distribution. The fluorescence emission spectra display an intense sharp emission at 365nm and weak broad intensity emission at 470nm. Picosecond fluorescence measurements of the nanoparticles suggest bi-exponential function giving time constants of τ₁ (330ps, 94.21%) and τ₂ (4.69ns, 5.79%). In neutral and alkaline solutions, Zeta potential values of CuO nanoparticles are negative, due to the adsorption of COO⁻ group via the coordination of bidentate. At low pH the zeta potential value is positive due to the increased potential of H⁺ ions in solution. Comparative UV–visible absorption experiments with the model amino acid compounds of positive and negative charges as arginine and aspartic acid, respectively confirmed the negative surface of CuO nanoparticles. The results should be extremely useful for understanding the mode of the interaction with biological systems. This binding process also affects the particle's behavior inside the body.

Keywords: Nanoparticles; CuO; Optical; Fluorescence; Decay; Amino acids; Electrostatic

Synthesis of TiN thin film on diamond surface for ferrous metal contacts by a new atom beam method by Hiroshi Kinoshita; Shunsuke Yamamoto; Hideaki Yatani; Tetsuo Nakai; Nobuo Ohmae (pp. 3002-3006).

► TiN thin film of a few tens of nm thick was synthesized on a diamond surface by simultaneous exposure to pulsed Ti arc plasma and hyperthermal neutral N atom beam. ► The TiN film showed no notable degradation and relative steady friction. ► The TiN thin film shows the efficacy of anti-wear of AFM applications.In order to prevent degradation of diamond surfaces in contact with ferrous metals, a TiN thin film of a few tens of nm thick was synthesized on a diamond surface with a Ti thin buffer layer of approximately 10nm by a new atom beam method. A diamond surface was simultaneously exposed to pulsed Ti arc plasma and hyperthermal neutral N atom beam generated from an arc plasma gun (APG) and a laser breakdown-type atom beam generator, respectively. Frictional experiment of the TiN thin film was conducted by an in situ scanning electron microscopic (SEM) tribometer using a 1mm diameter SUS304 pin with an applied force of 0.24N. The TiN film had a relative high friction coefficient (0.4), but this film showed no notable degradation and relative steady friction. In addition, a TiN coated diamond tip by the new atom beam method showed less wear than that of non-coated diamond tips by three times in the scratching tests of iron with using an atomic force microscope (AFM).

Keywords: TiN; Diamond surface degradation; Hyperthermal atom beam; Arc plasma deposition

The synthesis of a new kind of magnetic coating on carbon fibers by electrodeposition by Rui Wang; Yizao Wan; Fang He; Yu Qi; Wei You; Honglin Luo (pp. 3007-3011).

► Nickel/Fe₃O₄ nanoparticle (Ni/Fe₃O₄-NPs) composite coatings on the surface of carbon fiber were prepared. ► Ni/Fe₃O₄-NPs composite coatings are dense and uniformly deposited on the surface of carbon fibers. ► Fe₃O₄-NPs distribute homogenously in the composite coatings. ► Carbon fibers with Ni/Fe₃O₄-NPs composite coatings exhibit higher thermal stability and saturation magnetization.Nickel/Fe₃O₄ nanoparticle (Ni/Fe₃O₄-NPs) composite coatings on the surface of carbon fiber were prepared by electrodeposition in a nickel-plating bath containing Fe₃O₄ nanoparticles (Fe₃O₄-NPs). The composite of carbon fiber with nanocomposite coatings were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) analysis, thermogravimetric (TG) analysis and vibrating sample magnetometer (VSM). The microstructure observation reveals that the Fe₃O₄-NPs distribute uniformly in the coatings. TG and VSM analysis show that the carbon fibers with Ni/Fe₃O₄-NPs composite coatings exhibit higher thermal stability and saturation magnetization than carbon fiber with Ni coatings. The result is attributed to the homogeneous distribution of magnetic Fe₃O₄ in the composite coatings.

Keywords: Composite coatings; Carbon fiber; Electrodeposition; Magnetic property

Surface modification of CNTs and enhanced photocatalytic activity of TiO₂ coated on hydrophilically modified CNTs by Hanpei Yang; Sha Wu; Yunping Duan; Xiaofei Fu; Junming Wu (pp. 3012-3018).

► Hydrophilicity of CNTs was acquired by surface modification. ► Enhanced photoactivity of TiO₂ coated on modified CNTs was obtained. ► Improved activity of TiO₂ is attributed to the intimacy between TiO₂ and CNTs. ► Dense heterojunctions through Ti–O–CNTs at the interface is proposed.A new method to enhance photocatalytic performance of TiO₂ by dispersing it onto hydrophilically surface modified carbon nanotubes is reported. The hydrophilically surface functionalized CNTs and as prepared composite CNTs-TiO₂ photocatalysts were characterized using FT-IR, XPS, XRD, BET adsorption analysis and TEM. The composite samples were evaluated for their photocatalytic activity toward the degradation of methyl orange in aqueous solution under both UV and visible light irradiation. The results indicated that the hydrophilic functional groups were grafted covalently on the surface of CNTs successfully, and the functionalized CNTs exhibit higher BET specific surface area and aquatic solubility. The improved photocatalytic activity of CNTs-TiO₂ was mainly attributed to the high dispersion of TiO₂ on CNTs and the intimate contact between TiO₂ and CNTs resulting in dense heterojunctions at the interface of TiO₂ and CNTs.

Keywords: Hydrophilicity; CNTs-TiO; ₂; composite; Photodegradation; Methyl orange

Chemical and electrical passivation of Si(111) surfaces by Fangyuan Tian; Dan Yang; Robert L. Opila; Andrew V. Teplyakov (pp. 3019-3026).

► We compare hydrogen-passivated Si(111) surfaces prepared by two main procedures. ► We use modified RCA clean and HF-dip methods to prepare them. ► We test their electronic properties by measuring charge-carrier lifetimes. ► We test their chemical properties by chlorination and by reaction with 1-alkenes. ► We propose the ways to reconcile the differences in electronic and chemical properties.This paper compares the physical and chemical properties of hydrogen-passivated Si(111) single crystalline surfaces prepared by two main chemical preparation procedures. The modified RCA cleaning is commonly used to prepare atomically flat stable surfaces that are easily identifiable spectroscopically and are the standard for chemical functionalization of silicon. On the other hand electronic properties of these surfaces are sometimes difficult to control. A much simpler silicon surface preparation procedure includes HF dipping for a short period of time. This procedure yields an atomically rough surface, whose chemical identity is not well-defined. However, the surfaces prepared by this approach often exhibit exceptionally attractive electronic properties as determined by long charge carrier lifetimes. This work utilizes infrared spectroscopy and X-ray photoelectron spectroscopy to investigate chemical modification of the surfaces prepared by these two different procedures with PCl₅ (leading to surface chlorination) and with short- and long-alkyl-chain alkenes (1-decene and 1-octodecene, respectively) and follows the electronic properties of the starting surfaces produced by measuring charge-carrier lifetimes.

Keywords: Silicon single crystal; Charge-carrier lifetime; Surface preparation

Surface activation on multi-wall carbon nanotube for electrochemical capacitor applications by Yong-Ming Dai; Wen-Jay Liu; Tsung-Chi Pan; Jih-Mirn Jehng (pp. 3027-3032).

► The residual catalyst in the MWCNT can be easily removed after the air oxidation. ► The intensities functional groups increase with in the HNO₃ concentration. ► After the activated treatment, MWCNT possess –CO and –OH functional groups. ► The modification of the MWCNT increases their capacitance.The multi-walled carbon nanotube (MWCNT) was treated with HNO₃ to increase their surface area and improve their properties. Cyclic voltammetry (CV) was used to evaluate the optimize conditions of the modified MWCNT for the higher specific capacitance. After MWCNT are activated by treatment with 5M concentration of HNO₃ for 12h, the specific surface area of the MWCNT increases to 145m²/g. The CV performance of the modified MWCNT has shown that the specific capacitance increases from 8.9 to 22.6F/g. Thus, the modification of the MWCNT improves the surface properties and increases their capacitance for use in energy storage applications.

Keywords: Multi-walled carbon nanotube (MWCNT); Activation; Electrochemical capacitor

An all-silicon laser by coupling between electronic localized states and defect states of photonic crystal by Wei-Qi Huang; Zhong-Mei Huang; Xin-Jiang Miao; Chen-Lan Cai; Jia-Xin Liu; Quan Lü; Shi-Rong Liu; Chao-Jian Qin (pp. 3033-3038).

► In the research, we provide a new conception on nano-laser of Si quantum dots. ► The smaller Si quantum dots can be fabricated by nanosecond pulse laser. ► The quantum confinement effect can form the pumping level. ► Coupling between the active centers and the defect states of photonic crystal is used to select model.In a nano-laser of Si quantum dots (QD), the smaller QD fabricated by nanosecond pulse laser can form the pumping level tuned by the quantum confinement (QC) effect. Coupling between the active centers formed by localized states of surface bonds and the two-dimensional (2D) photonic crystal is used to select model in the nano-laser. The experimental demonstration is reported in which the peaks of stimulated emission at about 600nm and 700nm were observed on the Si QD prepared in oxygen after annealing which improves the stimulated emission. It is interesting to make a comparison between the localized electronic states in gap due to defect formed by surface bonds and the localized photonic states in gap of photonic band due to defect of 2D photonic crystal.

Keywords: PACS; 42.55.−f; 68.65.Hb; 78.45.+h; 78.55.MbSurface bonds; Si quantum dots; Localized states; Photonic crystal

Structural and optical properties of copper doped ZnO films derived by sol–gel by M. Caglar; F. Yakuphanoglu (pp. 3039-3044).

► The effect of Cu incorporation on the structural, morphological and optical properties of the ZnO film was investigated. ► The chemical composition of the Cu doped ZnO films were confirmed by XPS and XRD measurements. ► The refractive index dispersion was analyzed by single oscillator model developed by Wemple and DiDomenico. ► The obtained results indicate that the Cu dopant changes the structural and optical properties of the ZnO films.Undoped and copper doped ZnO (ZnO:Cu) films were prepared by sol–gel spin coating technique. The effect of Cu incorporation on the structural, morphological and optical properties of the Zinc oxide (ZnO) film was investigated. The chemical composition of the Cu doped ZnO films was confirmed by XPS and XRD measurements. The structural disorder was observed in XRD spectra depending on the Cu incorporation and these results were confirmed by the increasing Urbach energy values. The refractive index dispersion was analyzed by single oscillator model developed by Wemple and DiDomenico. The oscillator energy and dispersion energy values for the films were determined. The oscillator energy value E_o for the ZnO film decreases with Cu incorporation due to increase in the probability of electronic transitions between electronic bands. It is evaluated that the structural and optical properties of ZnO films can be controlled with Cu doping.

Keywords: ZnO; Cu doping; Sol–gel; Optical constants; Single oscillator model

A study of structure and properties of Ti-doped DLC film by reactive magnetron sputtering with ion implantation by Guojia Ma; Shuili Gong; Guoqiang Lin; Lin Zhang; Gang Sun (pp. 3045-3050).

► The Ti-doped DLC still held a lower abrasion loss at 450°C. ► The mean water contact-angle of DLC could be raised to 104.2° from 70° by Ti doping. ► By contrast with the substrate and unmodified DLC film, the mechanical properties of Ti-doped DLC film were significantly improved. ► Ion implantation can evidently strengthen the adhesion between film and substrate by forming compositionally graded layers. ► TiC nanocrystalline cluster were embedded in the amorphous hydrocarbon matrix.Ti-doped diamond-like carbon (DLC) films were prepared on Ti alloys by reactive magnetron sputtering combined with PSII technology. The structure and properties of unmodified and Ti-doped DLC films were analyzed in a systematic way by different testing, such as TEM, XPS, frictional wear testing, contact angle measurement and so on. The results showed that Ti-doped DLC was a typical a-C:H film containing TiC nanometer grains, whose mechanical properties were obviously improved, such as hardness, wear resistance and cohesive strength, still kept good wear resistance at the ambient temperature of 450°C, and held a rather large mean water contact angle of 104.2±1°.

Keywords: Ti doping; DLC; Ion implantation; Adhesion; Hydrophobic property

Effects of duty cycle on microstructure and corrosion behavior of TiC coatings prepared by DC pulsed plasma CVD by Ali Shanaghi; Ali Reza Sabour Rouhaghdam; Shahrokh Ahangarani; Paul K. Chu; Taghi Shahrabi Farahani (pp. 3051-3057).

Display Omitted► TiC coatings are deposited on steel by Plasma CVD at three different duty cycles. ► The proper duty cycle increases the corrosion resistance in aggressive media. ► Optimization of the duty cycles led to produce a smooth and fine-grained morphology. ► The proper duty cycle improves the electrochemical properties in aggressive media.Titanium carbide coatings are deposited on hot-work steel (H₁₁) by plasma-assisted chemical vapor deposition (PACVD) and the dependence of the corrosion behavior on fabrication parameters is investigated. Grazing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy (FESEM), Raman and electrochemical tests are used to study the structure as well as corrosion behaviors. Grazing incidence X-ray diffraction reveals the (200) plane implying that the TiC coatings are deposited via the kinetics-limited crystal growth mechanism and under thermodynamically stable conditions. The SEM results indicate that the formation of a homogeneous and uniform titanium carbide nanostructure coatings. Potentiodynamic and electrochemical impedance tests performed in 0.5M H₂SO₄ and 0.05M NaCl show that the TiC coating produced using a 40% duty cycle possesses high corrosion resistance in both media. The R_p values of the TiC coating (50% duty cycle) in 0.05M NaCl and the other TiC coating (40% duty cycle) in 0.5M H₂SO₄ are approximately four and sixteen orders of magnitude higher than that of the bare steel, respectively. Our results reveal that the duty cycles not only affect the structure and morphology of the coatings but also influence the electrochemical properties.

Keywords: TiC nanostructure coating; Corrosion behavior; Plasma CVD; Duty cycle

Mo/Cu(In, Ga)Se₂ back interface chemical and optical properties for ultrathin CIGSe solar cells by F. Erfurth; Z. Jehl; M. Bouttemy; N. Dahan; P. Tran-Van; I. Gerard; A. Etcheberry; J.-J. Greffet; M. Powalla; G. Voorwinden; D. Lincot; J.F. Guillemoles; N. Naghavi (pp. 3058-3061).

► Chemical and optical properties of the interface between a Cu(In,Ga)Se₂ (CIGSe) absorber and the Mo back contact are investigated. ► After the lift-off of the CIGSe absorber from the Mo layer, X-ray photoelectron spectroscopy (XPS) and ellipsometry are performed on these interfaces. ► The calculated optical reflectivity of the real Mo/CIGSe interface was found to be quite low. ► The enhancement of light absorption in ultrathin absorbers down to 100nm by using alternative, highly reflective back contacts is discussed.Chemical and optical properties of the interface between a coevaporated Cu(In,Ga)Se₂ (CIGSe) absorber thin film and the Mo back contact are investigated with the objective to reduce markedly the thickness of CIGSe layers from two microns down to about 100nm. First a mechanical lift off technique allowed to separate Mo and CIGSe layers and perform X-ray photoelectron spectroscopy (XPS) and elipsometry studies on as prepared surfaces. On the Mo side small amounts of In and Ga are observed together with the formation of an MoSe₂ layer. There is no evidence of the presence of Cu. On the opposite CIGSe side a clear depletion of Cu together with an enrichment of Ga is evidenced. There is no evidence of Mo. Optical reflectivity of the interface CIGSe/Mo is studied by ellipsometry showing a low reflectivity of the interface attributed to the formation of MoSe₂ layer. The enhance light absorption in ultrathin absorbers using alternative, highly reflective back contacts are finally discussed.

Keywords: CIGSe based solar cells; Back contact; X-ray photoelectron spectroscopy (XPS); Elipsometry; Interface

Wettability and friction coefficient of micro-magnet arrayed surface by Wei Huang; Sijie Liao; Xiaolei Wang (pp. 3062-3067).

► Micro-magnet arrayed films with different thicknesses were fabricated on the surface. ► A controllable colloid – ferrofluids was used as lubricant. ► Surface magnetic intensity of the films increases with the increasing film thickness. ► Wettability of ferrofluids on magnetic surface degrades for the thicker arrayed film. ► Surface with thicker arrayed films leads to lower friction at high sliding speed.Surface coating is an important part of surface engineering and it has been successfully used in many applications to improve the performance of surfaces. In this paper, magnetic arrayed films with different thicknesses were fabricated on the surface of 316 stainless steel disks. Controllable colloid – ferrofluids (FF) was chosen as lubricant, which can be adsorbed on the magnetic surface. The wettability of the micro-magnet arrayed surface was evaluated by measuring the contract angle of FF drops on surface. Tribological experiments were carried out to investigate the effects of magnetic film thickness on frictional properties when lubricated by FF under plane contact condition. It was found that the magnetic arrayed surface with thicker magnetic films presented larger contract angle. The frictional test results showed that samples with thicker magnetic films could reduce friction and wear more efficiently at higher sliding velocity under the lubrication of FF.

Keywords: Magnet arrayed surface; Wetting; Ferrofluids; Lubrication; Friction

Application of response surface methodology for optimization of the synthesis of synthetic rutile from titania slag by Guo Chen; Jin Chen; C. Srinivasakannan; Jinhui Peng (pp. 3068-3073).

► Response surface methodology was used to optimize the preparation parameters of synthetic rutile. ► The determination coefficient ( R²=0.9710) indicates a sufficient adjustment of the model with the experimental data. ► Raman spectroscopy was used to characterize the synthetic rutile under the optimum condition.In this work, response surface methodology (RSM) based on five-level, three-variable, and central composite design (CCD) was used to optimize the synthesis of synthetic rutile. With the TiO₂ content as the dependent variable, the effects of three independent variables, i.e. temperature, time, and mass, were investigated. The effects of several parameters on the TiO₂ content were systematically investigated to identify the optimal experimental conditions. In addition, Raman spectroscopy was used to characterize the synthetic rutile under the optimum condition. The results showed that the obtained second-order polynomial equation explains adequately the non-linear nature of the modeled response. The optimal conditions found to be at the temperature of 1358.30K, time of 58.77min, and mass of 80.97g. Under optimum conditions, the predicted TiO₂ content of synthetic rutile was 88.81% while the experimental date was 88.16%. The experimental value after process optimization was found to agree satisfactory with the predicted value. The demonstration of response surface methodology can be applied effectively and efficiently to the synthesis processing of synthetic rutile.

Keywords: Synthetic rutile; Titania slag; Response surface methodology; Central composite design; Raman spectroscopy

Surface characteristics and corrosion behaviour of WE43 magnesium alloy coated by SiC film by M. Li; Y. Cheng; Y.F. Zheng; X. Zhang; T.F. Xi; S.C. Wei (pp. 3074-3081).

Amorphous SiC film was successfully prepared on the surface of WE43 alloy by plasma enhanced chemical vapour deposition (PECVD) of CH₄ and SH₄. The immersion test indicated that SiC film could efficiently slow down the degradation rate of WE43 alloy and alleviate local alkalization in simulated body fluid (SBF) at 37±1°C (a and b) The indirect toxicity experiment was conducted using L929 cell line and the results showed that the extraction medium of SiC coated WE43 alloys exhibited no inhibitory effect on L929 cell growth (c). The in vitro hemocompatibility of the samples was investigated by hemolysis test and blood platelets adhesion test, and it was found that the hemolysis rate of WE43 alloy decreased after being coated by SiC and the platelets attached on the SiC film were slightly activated with a round shape (d). It could be concluded that SiC film prepared by PECVD made WE43 alloy more appropriate to biomedical application.Display Omitted► Amorphous SiC film has been successfully fabricated on the surface of WE43 magnesium alloy by PECVD. ► SiC film could efficiently slow down the degradation rate and alleviate local alkalization of WE43 alloy in simulated body fluid (SBF) at 37±1°C. ► It was found that the hemolysis rate of the SiC coated WE43 alloy decreased greatly.Amorphous SiC film has been successfully fabricated on the surface of WE43 magnesium alloy by plasma enhanced chemical vapour deposition (PECVD) technique. The microstructure and elemental composition were analyzed by transmission electron microscopy (TEM), glancing angle X-ray diffraction (GAXRD) and X-ray photoelectron spectroscopy (XPS), respectively. The immersion test indicated that SiC film could efficiently slow down the degradation rate of WE43 alloy in simulated body fluid (SBF) at 37±1°C. The indirect toxicity experiment was conducted using L929 cell line and the results showed that the extraction medium of SiC coated WE43 alloys exhibited no inhibitory effect on L929 cell growth. The in vitro hemocompatibility of the samples was investigated by hemolysis test and blood platelets adhesion test, and it was found that the hemolysis rate of the coated WE43 alloy decreased greatly, and the platelets attached on the SiC film were slightly activated with a round shape. It could be concluded that SiC film prepared by PECVD made WE43 alloy more appropriate to biomedical application.

Keywords: WE43 alloy; SiC film; PECVD; Corrosion; Hemocompatibility

Transparent conductive ITO/Cu/ITO films prepared on flexible substrates at room temperature by Xingwei Ding; Jinliang Yan; Ting Li; Liying Zhang (pp. 3082-3085).

► A SiO₂ buffer layer is inserted between the ITO/Cu/ITO film and PET substrate. ► The effect of Cu interlayer on properties of ITO/Cu/ITO films is studied. ► The ITO/Cu/ITO films with 40nm SiO₂ buffer layer reveal better figure of merits. ► The Cu interlayer improves the electrical properties. ► The SiO₂/ITO/Cu/ITO film with 5nm Cu interlayer has better optoelectronic properties.Transparent conductive ITO/Cu/ITO films were deposited on PET substrates by magnetron sputtering using three cathodes at room temperature. Effects of the SiO₂ buffer layer and thickness of Cu interlayer on the structural, electrical and optical properties of ITO/Cu/ITO films were investigated. The optical transmittance was affected slightly by SiO₂ buffer layer, but the electrical properties of ITO/Cu/ITO films were improved. The transmittance and resistivity of the SiO₂/ITO/Cu/ITO films decrease as the Cu layer thickness increases. The ITO/Cu/ITO film with 5nm Cu interlayer deposited on the 40nm thick SiO₂ buffer layer exhibits the sheet resistance of 143Ω/sq and transmittance of 65% at 550nm wavelength. The optical and electrical properties of the ITO/Cu/ITO films were mainly dependent on the Cu layer.

Keywords: Indium tin oxide; Copper; SiO; ₂; buffer layer; Flexible substrate

Comparison and SEM-characterization of novel solvents of DNA/carbon nanotube by Babak Sadeghi; R.A.R. Vahdati (pp. 3086-3088).

► Carbon nanotubes (CNTs) including not being soluble in aqueous and non-aqueous solutions. ► One method for dispersing and solubilizing them in aqueous solutions is attaching single stranded DNA to the outer wall of single walled carbon nanotubes. ► Rate of reaction between CNTs and DNA in three solvents possessing strong hydrogen bonds increase from: H₂ON, N’-dimethyl formamide (DMF).There have been many applications proposed for carbon nanotubes (CNTs). In spite of these applications they are not being used vastly for a few fundamental difficulties in utilizing them including not being soluble in aqueous and non-aqueous solutions. One method for dispersing and solubilizing them in aqueous solutions is attaching single stranded DNA to the outer wall of single walled carbon nanotubes. The effective parameter in the solubility (efficiency in gel filtration) is the strength of hydrogen bonds between CNTs and DNA in three solvents possessing strong hydrogen bonds: H₂O, methanol (MeOH) and N, N’-dimethyl formamide (DMF). Electronic absorption spectra, Superdex TM 200 10/300 gel-filtration and scanning electronic microscopy (SEM) also support van der Waals wrapping of DNA on CNTs. It was found that DMF exhibit higher solubility than MeOH and H₂O.

Keywords: Carbon nanotubes; DNA; Scanning electronic microscopy (SEM)

Effects of the interfacial layer on electrical characteristics of Al₂O₃/TiO₂/Al₂O₃ thin films for gate dielectrics by Chang Eun Kim; Ilgu Yun (pp. 3089-3093).

► Al₂O₃/TiO₂/Al₂O₃ thin films were fabricated using atomic layer deposition. ► The electrical properties were characterized depending on the annealing temperature. ► The dielectric constant and leakage current were affected by interfacial layer. ► Al₂O₃/TiO₂/Al₂O₃ thin film proved to be a possible candidate for the gate dielectric.Effects of thermal annealing on the electrical properties of Al₂O₃/TiO₂/Al₂O₃ (ATA) dielectric thin films prepared by atomic layer deposition are investigated. The structural properties and chemical states in the interfacial layer are analyzed with varying the annealing temperature. The dielectric constant and leakage current are affected by the formation of Al₂O₃–TiO₂ composite and interfacial layer including SiO_x in the interface by the annealing. The transformation of interfacial layer at the interface of the ATA/Si substrate due to the annealing is a critical point to apply ATA thin films as gate dielectric layers.

Keywords: Annealing; Atomic layer deposition; Electrical characterization; High-; k; dielectric; Interfacial layer

The temperature effect on the adsorption mechanism of polyacrylamide on the silica surface and its stability by Małgorzata Wiśniewska (pp. 3094-3101).

► I examine temperature effect on SiO₂ suspension stability in presence of PAM. ► I determine conformation of PAM chains in studied systems. ► I prove that structure of adsorption layer changes with increasing temperature. ► I show that temperature has minimal impact on silica suspension stability.The influence of temperature on the adsorption mechanism of polyacrylamide (PAM) on the silica surface was studied in the temperature range 15–35°C. The structure of polymer adsorption layer was determined from spectrophotometric, viscosity, surface charge and zeta potential measurements. These methods enable determination of the following parameters: adsorbed amount of polymer, macromolecules conformation in the solution and thickness of the polymer adsorption layer, surface charge density and zeta potential of SiO₂ particles in the absence and presence of PAM. The measurements of stability of silica suspension without and with adsorbed polyacrylamide were also carried out. The obtained results indicate that temperature influences the conformation of PVA chains in the solution and the structure of polymer adsorption layer. The temperature rise causes polymer coils developing which results in: the decrease of polymer adsorption, the increase of linear dimensions of PAM chains in the solution, the creation of thicker adsorption layer of the polymer on the solid surface and the slight lowering of zeta potential of solid particles. Taking into account the conformational changes of polymer chains with the increasing temperature main reasons responsible for stability of the investigated system were given.

Keywords: Key words; Polyacrylamide; Silica; Polymer adsorption layer; Suspension stability; Temperature influence

Easy-to-clean property and durability of superhydrophobic flaky γ-alumina coating on stainless steel in field test at a paper machine by Xiaoxue Zhang; Xuwen Liu; Jarmo Laakso; Erkki Levänen; Tapio Mäntylä (pp. 3102-3108).

► Superhydrophobic surface was not self-cleaning in the field test at a paper machine. ► Superhydrophobic surface was easily cleaned by washing after the field test. ► Superhydrophobic flaky γ-alumina coating survived rather well after the field test. ► Nanoindentation revealed a time-dependent plasticity and some flexibility of the surface flaky structure.Superhydrophobic flaky γ-alumina coating was prepared on AISI 316 2B stainless steel and was field-tested near size roll at a paper machine in a paper mill for 6 weeks consisting of two running periods of machine to check the easy-to-clean property and durability, as compared to an uncoated reference stainless steel. In the end of the field test, both the superhydrophobic and the reference stainless steel were fully covered with substances from the testing environment. Major part of the collected substances on the superhydrophobic stainless steel can be washed away by pressurized water; however, the collected substances remained on the reference stainless steel after washing. The field-tested samples were characterized visually and by stereomicroscopy, field emission scanning electron microscopy, laser profilometry and contact angle tester. The field test revealed the easy-to-clean property of the superhydrophobic surface and the superhydrophobic coating survived rather well after the first running period of 16 days in the field test. The resistance and durability of the superhydrophobic surface still needs to be further improved for longer term application in paper industry. Nanoindentation was used to further study the mechanical properties of the γ-alumina coating. It was found that the γ-alumina coating became much softer after transforming from flat to flaky form. In addition, the flaky γ-alumina coating demonstrated a phenomenon of time-dependent plasticity and some flexibility.

Keywords: Superhydrophobic; Easy-to-clean; Field test; Paper machine; Nanoindentation

Optical and structural properties of ZnO nanorods grown on graphene oxide and reduced graphene oxide film by hydrothermal method by U. Alver; W. Zhou; A.B. Belay; R. Krueger; K.O. Davis; N.S. Hickman (pp. 3109-3114).

► ZnO nanorods were grown on graphene oxide and reduced graphene oxide films with seed layers using hydrothermal method at 80°C for 120min. ► ZnO nanorods grown on RGO films with a seed layer show the single (002) orientation much stronger than that of ZnO nanorods on GO. ► No growing occurs on GO and RGO films without seed layer. ► Transmittance of ZnO nanorods grown on RGO films was measured about 83% at 550nm.ZnO nanorods were grown on graphene oxide (GO) and reduced graphene oxide (RGO) films with seed layers by using simple hydrothermal method. The GO films were deposited by spray coating and then annealed at 400°C in argon atmosphere to obtain RGO films. The optical and structural properties of the ZnO nanorods were systematically studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and ultraviolet-visible spectroscopy. The XRD patterns and SEM images show that without a seed layer, no ZnO nanorod deposition occurs on GO or RGO films. Transmittance of ZnO nanorods grown on RGO films was measured to be approximately 83% at 550nm. Furthermore, while transmittance of RGO films increases with ZnO nanorod deposition, transmittance of GO decreases.

Keywords: ZnO nanorods; Graphene oxide; Hydrothermal; Seed layer

One-step process for the fabrication of superhydrophobic surfaces with easy repairability by Jian Li; Hongqi Wan; Yinping Ye; Huidi Zhou; Jianmin Chen (pp. 3115-3118).

► Surperhydrophobic surfaces have been fabricated by a facile spray-coating method. ► The fabrication of superhydrophobic copper stearate surfaces involves a one-step process. ► The damaged superhydrophobic surface can restore superhydrophobicity property by spraying the copper stearate suspension again directly on the wrecked surface.A simple technique for fabrication of superhydrophobic surfaces was developed by spraying copper stearate suspension on various substrates. The copper stearate suspension is prepared by the reaction of copper acetate and stearic acid in ethanol solution. The as-prepared surfaces exhibit both superhydrophobicity and self-cleaning properties. When the superhydrophobic surfaces were destroyed, the damaged surfaces could be easily repaired by spraying the copper stearate suspension on the wrecked surfaces again, and the superhydrophobicity of the surfaces was regenerated at the same time.

Keywords: Superhydrophobic; Contact angle; Self-cleaning property; Repairability

Surface chemical characterization of nanoparticle coated paperboard by Milena Stepien; Jarkko J. Saarinen; Hannu Teisala; Mikko Tuominen; Mikko Aromaa; Jurkka Kuusipalo; Jyrki M. Mäkelä; Martti Toivakka (pp. 3119-3125).

► TiO₂ nanoparticles on paperboard induce superhydrophobicity and SiO₂ hydrophilicity. ► SiO₂ nanoparticles have the highest O/C ratio related to hydroxyl groups. ► TiO₂ nanoparticles have highest carbon C1 amount due to aliphatic chains. ► Hydroxyl groups induce surface hydrophilicity, aliphatic chains hydrophobicity.The chemical composition of nanoparticle coated paperboard surfaces was characterized. The deposition of SiO₂ and TiO₂ nanoparticles induced changes in wetting properties of the paperboard surface: a superhydrophilic surface was created by SiO₂ nanoparticles and a superhydrophobic surface by TiO₂ nanoparticles. Both X-ray photoelectron spectroscopy (XPS) and contact angle (CA) measurements were used to study the surface properties of the samples. The low and high resolution XPS spectra were collected to evaluate the chemical composition before and after nanoparticle deposition. The SiO₂ nanocoated sample has the highest values of both O to C and C2 to C1 ratios, which indicates a high relative amount of hydroxyl groups. On the other hand, carbon C1 peak which represents the hydrocarbon type of bonds, is on higher level for TiO₂ when compared to the SiO₂ nanocoated sample. This may be related to the replacement of hydroxyl groups by aliphatic chains on the superhydrophobic surface of TiO₂ nanoparticle coated sample.

Keywords: Liquid flame spray process; Nanocoatings; Surface chemistry; Paperboard

Microstructure analysis of the ferromagnetic Ag–Ni system synthesized by pulsed electrodeposition by Kalavathy Santhi; S.N. Karthick; Hee-Je Kim; Marimuthu Nidhin; V. Narayanan; A. Stephen (pp. 3126-3132).

► Though Ag and Ni are immiscible according to their phase diagram Ag–Ni alloy has been synthesized by pulsed electrodeposition from a nontoxic electrolyte at room temperature. ► As far as we know, this method has not been used for Ag–Ni synthesis in any of the previous reports. ► The microstructure of the as deposited materials in various compositions has been analyzed along with their magnetic behavior. ► Ag–Ni alloy nanometrials with desired magnetic properties can be tailored by this method and used in preparing multilayers.Nanocrystalline silver–nickel deposits were prepared by pulsed electrolysis at different current densities from nontoxic complex electrolytes of two compositions containing silver nitrate and nickel sulphate. The structural and magnetic properties of these deposits have been analyzed in comparison with those of pure Ag and pure Ni deposited under similar conditions. The morphological and the microstructural studies have been carried out for these samples using SEM and HRTEM. The results suggest that the as deposited materials consist of Ag–Ni in the metastable alloy form. Heating the sample beyond Curie temperature leads to grain growth and long range ordering. The hysteresis curves and the magneto-thermograms reveal that the deposits exhibit room temperature ferromagnetism.

Keywords: Electrodeposition; Ag–Ni alloy; Magnetic materials; Nanoparticles; Pulsed electrolysis; Microstructure

Density functional theory study on oxygen adsorption in LaSrCoO₄: An extended cathode material for solid oxide fuel cells by Jun Zhou; Gang Chen; Kai Wu; Yonghong Cheng; Bo Peng; Jiaojiao Guo; Yizhe Jiang (pp. 3133-3138).

► The oxygen vacancy can be easily formed in both bulk LaSrCoO₄ and LaSrCoO₄ (010) surface by the DFT calculation. ► The adsorbed intermediates on the perfect surface are energetically less favorable than defect surface. ► The Co site is most preferred with an adsorption energy of 3.099 (super) and 5.425 (per) eV.Solid oxide fuel cell (SOFC) is one of the most promising technologies for a clean and secure source of energy in future due to its high energy efficiency and outstanding fuel flexibility. The search for new materials operating at low-temperature in order to make SOFCs economically competitive is a great challenge facing us today. In this report, atomistic computer simulation based on density functional theory (DFT) has been used to predict the formation of oxygen vacancy and the strong oxygen adsorption kinetics mechanisms in LaSrCoO₄. The optimal adsorption configurations as well as the adsorption energies for oxygen molecule adsorption on various sites of LaSrCoO₄ (010) surface were derived. Furthermore, a strong hybridization between Co and O and shorter Co–O bond length for molecular adsorption were obtained by analysis of density of states. The calculated results imply that LaSrCoO₄ could serve as possible cathode material due to its low formation and migration energies of oxygen vacancies.

Keywords: Oxygen vacancy formation; LaSrCoO; ₄; Oxygen adsorption; DFT

Influence of LbL surface modification on oxygen cross-over in self-assembled thin composite membranes by Serpil Yılmaztürk; Nevra Ercan; Hüseyin Deligöz (pp. 3139-3146).

Display Omitted►PO2 of self-assembled composite membrane is lower than that of pristine Nafion. ► The significant reduction inPO2 is due to the formation of thicker bilayers. ► Diffusion coefficient ( D) increases while solubility ( S) decreases with temperature. ► WhilePO2 decreases with the number of layers, σ of (PAH/PSS)_n–Na⁺/H⁺ increases. ► 10 bilayers deposition result in acceptable limitedPO2.The paper is concerned with the investigation of oxygen transport in layer-by-layer (LbL) self assembly of polystyrene sulfonic acid sodium salt (PSS) and polyallylamine hydrochloride (PAH) on Nafion membrane depending on the number of deposited bilayers, ion type within the multilayers and temperature. It is observed from SEM analysis that the polyelectrolyte layers growth on each side of Nafion membrane regularly. The oxygen permeability(PO2) of (PAH–PSS)₂₀ is 691cm³/(m²daybar) at 25°C whilePO2 of pristine Nafion is 2329cm³/(m²daybar) at the same temperature. This significant reduction (70.3%) in gas permeability can be explained by the formation of LbL multilayers which both restrict the mobility of gas through the polymer matrix and adjust gas solubility properties in conjunction with ion–dipole interaction between the polar phase of Nafion and the secondary ammonium groups of PAH. (PAH/PSS)₂₀–Na⁺ and (PAH/PSS)₂₀–H⁺ exhibit 64.4% and 52.3% reduction in oxygen permittivity at 25°C in comparison with the pristine Nafion^®117, respectively, while the proton conductivities of these membranes are 106.9 and 136.9mS/cm. Promisingly, it is found that the membrane selectivity values ( Φ) of all multilayered membranes in both H⁺ and Na⁺ form are much higher than that of perfluorosulfonated ionomer. The thickness of deposited bilayers dominates the diffusion and solubility properties of oxygen through the composite membrane while the major effect of surface hydrophilicity is not observed on oxygen permeability.

Keywords: Composite membrane; Layer-by-layer (LbL); Oxygen permeation; Proton conductivity; Self-assembly

Preparation of a spinel Li₄Ti₅O₁₂ (111) surface from a rutile TiO₂ single crystal by Mitsunori Kitta; Tomoki Akita; Yasushi Maeda; Masanori Kohyama (pp. 3147-3151).

► An atomically flat Spinel Li₄Ti₅O₁₂ (111) surface was successfully prepared. ► About 15μm thick of thin film Li₄Ti₅O₁₂ crystal was formed on rutile TiO₂ (111) surface. ► About 0.5nm steps and atomically flat teracces were confirmed on the film surface by AFM. ► Electrochemical properties of Li₄Ti₅O₁₂ film was enough to use as battery materials.Spinel Li₄Ti₅O₁₂ is a very promising material for electrodes in a wide range of Li-ion battery applications because of its unique Li-insertion/extraction properties. Although the bulk properties of Li₄Ti₅O₁₂ have been studied intensively, there have been few reports about the structure and properties of Li₄Ti₅O₁₂ surfaces in spite of the importance of solid/electrolyte interfaces. This is because of the difficulty in preparing Li₄Ti₅O₁₂ samples with accessible flat surfaces suitable for scanning probe microscopy study. To address this, we have successfully prepared a flat Li₄Ti₅O₁₂ crystal surface by solid state reaction from a rutile TiO₂ (111) wafer with LiOH·H₂O powder. Out-of-plane X-ray diffraction (XRD) and transmission electron microscopy revealed that a highly oriented and crystallized Li₄Ti₅O₁₂ (111) film was formed on the TiO₂ (111) wafer. Atomic force microscopy observations revealed that an atomically flat Li₄Ti₅O₁₂ (111) surface was formed on the film with terraces of 200–300nm width and steps of a {111} interplanar height. The formed thin films were also investigated by cyclic voltammetry and galvanostatic experiments, revealing that the films have electrochemical activity as battery electrodes.

Keywords: Li ion battery; Li; ₄; Ti; ₅; O; ₁₂; Atomically flat surface; SPM study

Preparation and characterization of TiO₂-cationic hybrid nanoparticles as electrophoretic particles by Jingjing Li; Liandong Deng; Jinfeng Xing; Anjie Dong; Xianggao Li (pp. 3152-3157).

► A kind of new cationic electrophoretic particles is prepared in this paper. ► The TiO₂ (core)–polymer (shell) nanoparticles are prepared via ATRP. ► The electrophoretic particles have a narrow size distribution. ► The electrophoretic dispersion possesses good optical properties.The hybrid nanoparticles (TiO₂-HNPs) with TiO₂ nanoparticles as core and with poly( N, N-dimethylaminoethyl methacrylate- co-methyl methacrylate) by using triallylamine as cross-linking agent as shell were firstly prepared via atom transfer radical polymerization (ATRP) in methanol. Then the hybrid nanoparticles with positive charge were produced by the quaternization with methyl iodide as quaternization reagent so as to endow them with greater electrophoretic mobility. The cationic hybrid nanoparticles (TiO₂-CHNPs) were studied by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and dynamic light scattering (DLS) measurements. The results indicate that the cationic polymer is successfully grafted on the surface of the TiO₂ nanoparticles. The particle size of TiO₂-CHNPs is about 150nm and the polydispersity index (PDI) is 0.307. The zeta potential, the contrast ratio of white state to dark state and response time of TiO₂-CHNPs are +16.8mV, 30 and 3s, respectively, which show the potential application prospect in the development of electrophoretic ink.

Keywords: TiO; ₂; Hybrid nanoparticles; ATRP; Electrophoretic ink

Copper diffusion barrier performance of amorphous Ta–Ni thin films by Hua Yan; Yee Yan Tay; Yueyue Jiang; Natalia Yantara; Jisheng Pan; Meng Heng Liang; Zhong Chen (pp. 3158-3162).

► Amorphous Ta–Ni thin films were deposited on Si substrate by magnetron sputtering. ► The amount of oxygen in the film was adjusted by controlling the substrate bias. ► Copper diffusion experiment was carried out by thermal heating at higher temperatures. ► Ta–Ni amorphous thin films was found to be an effective copper diffusion barrier. ► Incorporation of a few percent of oxygen into the film can retard copper diffusion.Amorphous Ta–Ni thin films were deposited on Si substrate by magnetron sputtering. The oxygen concentration was adjusted by controlling the substrate bias during the sputtering deposition. Two types of Ta–Ni films, namely Ta_67.34Ni_27.06O_5.60 and Ta_73.25Ni_26.10O_0.65 were employed in the current study. To assess the diffusion barrier performance, Cu/Ta–Ni/Si stacks were fabricated in sequence without breaking the vacuum. The samples were then annealed in vacuum for 30min at temperatures ranging from 500°C to 800°C. SEM, 4-point probe, SIMS and TEM have been used to study the film properties to assess the barrier performance. The films were found to remain stable up to 600°C without significant Cu diffusion. At 700°C, Cu diffusion through the barrier film was detected in both types of samples, but with different degree of severity. For the Ta_67.34Ni_27.06O_5.6 barrier film, there was no Cu–Si reaction at 700°C, while Cu₃Si was observed at the Ta_73.25Ni_26.10O_0.65/Si interface. At 800°C, Cu₃Si crystalline phase was found in both samples, and the barrier films have completely lost integrity. This study shows that sputter deposited Ta–Ni amorphous thin films can be used as an effective copper diffusion barrier for microelectronic device fabrication. Incorporation of a few percent of oxygen into the film can retard copper diffusion and interface reaction, which enhances the barrier performance.

Keywords: Cu diffusion; Barrier; Amorphous thin films; Ta–Ni; Crystallalization

Adsorption of NO on MoO₃ (010) surface with different location of terminal oxygen vacancy defects: A density functional theory study by Zhifeng Yan; Zhijun Zuo; Xueyong Lv; Zhen Li; Zhe Li; Wei Huang (pp. 3163-3167).

► The formation of two adjacent terminal oxygen vacancies is slightly easier than that of two diagonal terminal oxygen vacancies. ► NO can only adsorb on the cluster holding terminal oxygen vacancy. ► NO preferentially occupies the terminal oxygen vacancy site with N bonds to the surface. ► The presence of another surrounding terminal oxygen vacancy site further promotes the adsorption ability and the activation of NO.Density functional theory (DFT) cluster studies on the MoO₃ (010) surface are carried out to examine formation of different locations of terminal oxygen vacancies and adsorption of NO in this work. The formation of two adjacent terminal oxygen vacancies requires almost twice energy of formation of one terminal oxygen vacancy, and the formation of two adjacent terminal oxygen vacancies is slightly easier than that of two diagonal terminal oxygen vacancies. NO can only adsorb on the cluster holding terminal oxygen vacancy and preferentially occupies the terminal oxygen vacancy site with N bonds to the surface. The increase of N–O bond length and the decrease of N–O bond order before and after NO adsorption indicate that one terminal oxygen vacancy can improve the activation of NO. The presence of another surrounding terminal oxygen vacancy further promotes the adsorption ability and the activation of NO.

Keywords: DFT; MoO; ₃; (0; 1; 0) surface; Clusters; O; _T; vacancy; NO; Adsorption

Anhydride modified silica nanoparticles: Preparation and characterization by A.I. Barabanova; T.A. Pryakhina; E.S. Afanas’ev; B.G. Zavin; Ya.S. Vygodskii; A.A. Askadskii; O.E. Philippova; A.R. Khokhlov (pp. 3168-3172).

► The paper describes modification of colloid silica nanoparticles, using 3-(triethoxysilyl)propylsuccinic anhydride (TESPSA). ► Elemental analysis, FTIR and¹H NMR spectroscopy demonstrated that only 50% of silica surface silanol groups reacted with TESPSA. ► Atomic force microscopy (AFM) technique shows that nanoparticles preserve their size upon modification. ► TESPSA-modified silica nanoparticles can be used as polyfunctional curing agent for epoxy resin.The paper describes modification of colloid silica nanoparticles, using 3-(triethoxysilyl)propylsuccinic anhydride (TESPSA) as a reagent. Anhydride groups were grafted to the silica surface by an interaction of the surface silanol Si–OH groups with reactive ethoxy groups of TESPSA. Elemental analysis, FTIR and¹H NMR spectroscopy were employed to characterize silica nanoparticles before and after surface modification. It was demonstrated that only fifty percent of silica surface silanol groups are involved in the reaction with TESPSA. Size distribution of nanoparticles determined by atomic force microscopy (AFM) technique shows that nanoparticles preserve their size upon modification. TESPSA-modified silica nanoparticles can be used as polyfunctional curing agent for epoxy resin.

Keywords: Silica nanoparticles; Surface modification; Epoxy nanocomposite

In situ formation of titanium carbide using titanium and carbon-nanotube powders by laser cladding by M.M. Savalani; C.C. Ng; Q.H. Li; H.C. Man (pp. 3173-3177).

► By pre-deposition of pure titanium powder and carbon nanotubes on titanium substrate, Ti/TiC cerment coatings were synthesized after laser cladding. ► The coatings consisted of a matrix of alpha-titanium phases and the reinforcement phase of titanium carbide in the form of fine dendrites. ► When the wt% of CNTs was 20%, the micro-hardness of cladding layer was up to 6 times more than that of Ti substrate. ► The wear resistance of the TiC strengthening coating is approximately 3 times higher than that of the substrate for 20wt% CNTs under room temperature.Titanium metal matrix composite coatings are considered to be important candidates for high wear resistance applications. In this study, TiC reinforced Ti matrix composite layers were fabricated by laser cladding with 5, 10, 15 and 20wt% carbon-nanotube. The effects of the carbon-nanotube content on phase composition, microstructure, micro-hardness and dry sliding wear resistance of the coating were studied. Microstructural observation using scanning electron microscopy showed that the coatings consisted of a matrix of alpha-titanium phases and the reinforcement phase of titanium carbide in the form of fine dendrites, indicating that titanium carbide was synthesized by the in situ reaction during laser irradiation. Additionally, measurements on the micro-hardness and dry sliding wear resistance of the coatings indicated that the mechanical properties were affected by the amount of carbon-nanotube in the starting precursor materials and were enhanced by increasing the carbon-nanotube content. Results indicated that the composite layers exhibit high hardness and excellent wear resistance.

Keywords: Titanium; Laser cladding; Microstructure; Wear resistance; Hardness

Surface analysis correlated with the Raman measurements of a femtosecond laser irradiated Ca F₂ by M. Shahid Rafique; Shazia Bashir; Wolfgang Husinsky; Alison Hobro; Bernhard Lendl (pp. 3178-3183).

► Formation of nanohillocks by a fs laser is due to fast electronic processes. ► Ultrafast melting is the cause of bump formation. ► Crater is the formed due to enhanced thermal processes.Ultra fast electronic and thermal processes for energy deposition mechanism during femtosecond laser ablation of CaF₂ have been identified by means of Atomic Force Microscopy (AFM) and Raman scattering technique. For this purpose, a single crystal CaF₂ (111) was exposed with 800nm, 25fs Ti: Sapphire laser pulses at different laser fluences both in air and under UHV condition. Various nano and microstructures on the surface of the irradiated samples are revealed by a detailed surface topography analysis. Around the ablation threshold fluence, most significant features identified at the CaF₂ surface are nanohillock like structures. These nanohillocks are typical features related to the fast electronic processes and are explainable on the basis of Coulomb explosion. At moderate irradiation fluence, bump formation is considered to be due to ultrafast melting. Further increase in the laser fluence resulted into strong enhancement of the thermal process with the appearance of larger humps and craters. These fast electronic and thermal processes are well correlated with the structural and crystallographic alterations inferred from Raman spectroscopy analysis. The nanohillocks appearing at a lower fluence are due to calcium colloid formation (aggregates of metal clusters). At higher fluences and dozes, the compressive as well as tensile stresses along with the presence of calcium carbonate are associated to diffusion, transformation and aggregation of defects which are typical features of thermal processes leading to the growth of larger humps.

Keywords: PACS; 61.82.Pv; 68.37.Ps; 79.20.Ds; 61.80.BaTi: sapphire laser; AFM; Nanohillocks; Bumps; Raman spectroscopy

Microwave absorbing properties of polyaniline/multi-walled carbon nanotube composites with various polyaniline contents by T.H. Ting; Y.N. Jau; R.P. Yu (pp. 3184-3190).

► The polyaniline/multi-walled carbon nanotubes composites had been prepared by in situ polymerization method. ► We discussed in synthesis, characterization and microwave absorption. ► Increasing PANI content enhances the complex permittivity. ► The reflection loss varies with changes content of PANI for the required frequency bands.Polyaniline/multi-walled carbon nanotube (PANI/MWNT) composites were synthesized using in situ polymerization at different aniline/multi-walled carbon nanotube weight ratios (Ani/MWNT=1/2, 1/1, 2/1 and 3/1) and introduced into an epoxy resin to act as a microwave absorber. The spectroscopic characterization of the process of formation of PANI/MWNT composites were studied using Fourier transform infrared spectroscopy, an ultraviolet–visible spectrophotometer, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and electron spin resonance. The microwave absorbing properties were investigated by measuring complex permittivity, complex permeability and reflection loss in the 2–18 and 18–40GHz microwave frequency range, using the free space method. The results showed that the addition of PANI was useful for achieving a large absorption over a wide frequency range, especially for higher frequency values.

Keywords: Polymer–matrix composites; Electrical properties; Magnetic properties; Scanning/transmission electron microscopy

Monolayer formation of octyltrimethoxysilane and 7-octenyltrimethoxysilane on silicon (100) covered with native oxide by Philip Niehoff; Petra Ebbinghaus; Patrick Keil; Andreas Erbe (pp. 3191-3196).

Display Omitted► Conditions for alkoxysilane monolayer formation from solution have been identified. ► Alkyl and vinyl-terminated monolayers on silicon with native oxide have been prepared. ► Monolayers are found to be ultrasmooth but possess disordered chains. ► Endgroups in vinyl-terminated chains can be hydroxylated.Modification has been carried out of silicon (100) covered with native oxides with monolayers of octyltrimethoxsilane (C8TMS) and octenyltrimethoxysilane (C8enTMS). Different conditions of adsorption from the organic solvents chloroform, toluene and n-hexane with subsequent exposure to ammonia vapour under ambient atmosphere have been tested for monolayer formation without exclusion of moisture. Thickness of resulting adsorbates has been measured using spectroscopic ellipsometry (SE), water contact angles were measured, and the surface roughness was determined by atomic force microscopy (AFM). If all three results are consistent with the presence of monolayers on the surface, further characterisation has been carried out by angle dependent X-ray photoelectron spectroscopy (XPS). For monolayers, surface roughnesses about <0.3nm were measured, which were mainly determined by the substrate. Thicknesses obtained from SE and XPS agree. Conformational and orientational order of the monolayers determined by attenuated total reflection infrared (ATR-IR) spectroscopy show disordered chains in both cases with nearly isotropic orientation. C8enTMS was found to be partly hydroxylated when treated under alkaline conditions.

Keywords: Silane monolayer; Vinyl-terminated monolayer; Multilayer; Surface characterisation; Adhesion promoter

Mn₃N₂ as a novel negative electrode material for rechargeable lithium batteries by Qian Sun; Zheng-Wen Fu (pp. 3197-3201).

The lithium electrochemistry of Mn₃N₂ thin films fabricated by magnetron sputtering has been investigated by galvanostatic cell cycling and cyclic voltammetry for the first time. The reversible capacities of Mn₃N₂ thin film electrodes under the discharging currents of 80mA/g and 160mA/g were found to be 579mAh/g and 500mAh/g respectively. The electrochemical reaction mechanisms involving the irreversible conversion from Mn₃N₂ to Mn and Li₃N in the first discharging process and the reversible transformation between Mn with Li₃N and Mn₆N_2.58 in subsequent cycles were proposed. The irreversible electrochemical reaction mechanism results in an unavoidable capacity loss and low columbic efficiency of 70% in the first cycle. The high reversible capacity, good cycle performance and low polarisation of Mn₃N₂ film electrode make it potential anode material for future lithium-ion batteries.

Keywords: Mn; ₃; N; ₂; Anode materials; Lithium ion batteries; Magnetron sputtering

Properties of phase separation method synthesized superhydrophobic polystyrene films by Aruna S.T.; Binsy P.; Edna Richard; Bharathibai J. Basu (pp. 3202-3207).

► Superhydrophobic films from polystyrene using different non-solvents. ► Higher contact angles attributed to higher roughness.► Flory Huggin's interaction parameter showed ethanol to be the best non-solvent.► Raman and IR studies show isotactic to atactic transformation with the addition of ethanol.► Microstructural variations with vol% of ethanol and amount of PS.Polystyrene (PS) based superhydrophobic films were prepared by non-solvent induced phase separation method using tetrahydrofuran (THF) as the solvent and different alcohols as non-solvents. Flory Huggins interaction parameter values of different alcohols and acetone with PS were calculated to qualify them as non-solvents for phase separation. The films were characterized using contact angle analyser, field emission scanning electron microscope, surface roughness profilometer, IR spectrometer and Raman spectrometer. The coatings exhibited a maximum water contact angle (WCA) of 159° and a sliding angle (SA)<2°. With increase in the vol% of non-solvent, WCA increased and SA decreased. The microstructures of the films varied with the vol% of non-solvent and the amount of PS. The work of adhesion of PS films decreased with increasing WCA. The Raman spectral studies showed isotactic to atactic transformation of PS with the addition of non-solvents and these results corroborated well with the IR spectral studies.

Keywords: Superhydrophobic; Polystyrene; Phase-separation; Water contact angle; Microstructure

Preparation, structure and properties of multi-functional silk via ATRP method by Tieling Xing; Weilin Hu; Shiwei Li; Guoqiang Chen (pp. 3208-3213).

Display Omitted► Multi-functional silk with flame retardance and antibacterial property was prepared. ► The multi-functional silk was prepared through ATRP method. ► The flame retardance and antibacterial property of silk had good washing resistance. ► The wearability of grafted silk fabric was little affected.In order to develop multi-functional silk materials, silk was grafted using the first flame retardant monomer, dimethyl methacryloyloxyethyl phosphate (DMMEP), and the second antibacterial monomer, dimethylaminoethyl methacrylate (DMAEMA), via atom transfer radical polymerization (ATRP) method. The result of attenuated total reflection-Fourier transformed infrared spectroscopy (ATR-FTIR) indicated that two monomers were successfully grafted onto silk surface. X-ray diffraction (XRD) curves showed that grafting mainly occurred at the amorphous region of silk fibers. Thermal gravimetric analysis (TGA) and flame retardance measurements indicated that the Silk-grafted-poly(DMMEP) (Silk-g-PDMMEP) and Silk-grafted-poly(DMMEP)-blocked-poly(DMAEMA) (Silk-g-PDMMEP-b-PDMAEMA) both had good flame retardance. The LOI value could reach 31.2% and the char length was less than 6cm for the Silk-g-PDMMEP sample with 22.21% of grafting percentage, and the LOI value was still over 28% after 50 times of washing. And the second grafts of DMAEMA monomer had no distinct effect on the flame retardance of Silk-g-PDMMEP. The inhibition rates of quaternized grafted silk to Staphylococcus aureu and Escherichia coli were both over 88%, and had excellent washing fastness. Multi-functional silk fabric with good flame retardance and anti-bacterial property could be obtained by properly controlling the grafting percentage, which had little effect on the intrinsic properties of silk fabric.

Keywords: Silk; Grafting; ATRP; Flame retardance; Antibacterial property

Effects of WC particle size on the wear resistance of laser surface alloyed medium carbon steel by Xin Tong; Fu-hai Li; Min Kuang; Wen-you Ma; Xing-chi Chen; Min Liu (pp. 3214-3220).

► Surface MMC is formed by laser surface alloying with WC on medium carbon steel. ► Wear resistance of 45Mn2 steel is improved. ► Over 63% enhanced degrees of wear resistance are achieved. ► Powder size affects hardness amount and distribution of WC in the laser alloyed layer. ► Too fine or too thick used WC powders are all bad for the wear resistance.The CO₂ laser surface alloying technique was used to form wear resistance layers on medium carbon steel with a kind of spherical WC powder. The effects of WC particle size on the abrasive wear resistance were thoroughly investigated. The results indicate that the laser alloyed layer is characterized by dendritic primary phase and ledeburite microstructure, consisting of austenite, martensite and carbides of Fe₃W₃C, W₂C and WC. The laser surface alloying with WC powder could improve the abrasive wear resistance of the medium carbon steel by over 63%. The factors such as the hardness, the amount and the distribution of WC particle determined the laser alloyed samples’ wear resistance, and the laser alloyed sample with WC powder of 88–100μm diameter presented the best wear resistance in this study. Furthermore, the wear resistance mechanisms of the laser alloyed layers were also explored.

Keywords: WC particle; Laser; Surface; Wear; Steel

Low-temperature (120°C) growth of nanocrystalline silicon films prepared by plasma enhanced chemical vapor deposition from SiCl₄/H₂ gases: Microstructure characterization by L. Zhang; J.H. Gao; J.Q. Xiao; L.S. Wen; J. Gong; C. Sun (pp. 3221-3226).

► SiCl₄ enables the formation of nanocrystal silicon films at low temperature as low as 120°C. ► The microstructure and hydrogen content of the films are investigated. ► The film transforms from amorphous to nanocrystalline phase. ► We analyze the effect of hydrogen flow rates on the microstructure of films.Hydrogenated nanocrystalline silicon (nc-Si:H) films were prepared using diluted tetrachlorosilane (SiCl₄) with various hydrogen flow rates ( Hf) by plasma enhanced chemical vapor deposition (PECVD) at a constant substrate temperature ( Ts) as low as 120°C. Raman spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), infrared spectra (IR) and spectroscopic ellipsometry (SE) were employed to investigate the microstructure and hydrogen bonding of the nc-Si:H films. Our results showed that the microstructure and hydrogen content of the films could be effectively tailored by the hydrogen flow rates, and a distinct transition from amorphous to nanocrystalline phase was observed with an increase of Hf. At an optimal preparation condition, a deposition rate was as high as 3.7nm/min and the crystallinity reached up to 64.1%. In addition, the effect of hydrogen on the low-temperature growth of nc-Si:H film was proposed in relation to the surface reaction of radicals and the hydrogen diffusion in the surface growing region.

Keywords: Nanocrystalline silicon; PECVD; Microstructure; Raman spectra

In situ measurement of the kinetic friction of ZnO nanowires inside a scanning electron microscope by Boris Polyakov; Leonid M Dorogin; Ants Lohmus; Alexey E Romanov; Rynno Lohmus (pp. 3227-3231).

► ZnO nanowires manipulated on oxidised silicon and graphite inside scanning electron microscope. ► NW dragged at midpoint bends into an arc due to the kinetic friction force. ► Elastically bend profile of NW used to determine the distributed kinetic friction.A novel method for measuring the kinetic friction force in situ was developed for zinc oxide nanowires on highly oriented pyrolytic graphite and oxidised silicon wafers. The experiments were performed inside a scanning electron microscope and used a nanomanipulation device as an actuator, which also had an atomic force microscope tip attached to it as a probe. A simple model based on the Timoshenko elastic beam theory was applied to interpret the elastic deformation of a sliding nanowire (NW) and to determine the distributed kinetic friction force.

Keywords: Nanotribology; SEM; Nanowire; Zinc oxide; Graphite; Silicon

Morphology evolutions and optical properties of Cu₂O films by an electrochemical deposition on flexible substrate by Yuchun Zhai; Huiqing Fan; Qiang Li; Wei Yan (pp. 3232-3236).

► We improve a method for preparing structure-tunable Cu₂O particles on ITO–PET substrate, which shows dramatic changes in morphology. ► The peaks potential shift to negative due to selective adsorption of citric ions on {111} and {100} facets with the increasing of electrodeposition time. ► The plots of (α E_photon)² versus E_photon, indicates a blue shift from what normally observed at around 570nm, which can be ascribed to the quantum confinement effect.Micro crystals of cuprous oxide (Cu₂O) with different morphologies, evolving from cubes, tetrahedrons, truncated cubes and final to truncated octahedrons, were obtained on indium tin oxide (ITO) flexible substrate (polyethylene terephthalate-PET) by simply adjusting the electrochemical deposition time. We elucidated the underlying morphology evolution mechanism using the cyclic voltammogram (CV), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optical properties of Cu₂O films were characterized by the ultraviolet–visible (UV–vis) spectrum, which demonstrated the band gap changing from 2.21eV to 2.43eV with different electrochemical deposition time owing to the quantum confinement effect.

Keywords: Microstructure; Electrochemical deposition; Cu; ₂; O films; Optical properties

Structural, electrical and magnetic properties of Fe network films grown on nanochannel Al₂O₃ substrates by direct current magnetron sputtering with the oblique target by Hua Zong; Hong Qiu; Yueping Zuo; Ruqiang Zheng; Jingle Pan; Jianping He (pp. 3237-3243).

► The Fe network films were sputter-deposited on nanochannel Al₂O₃ substrates. ► The 120nm-thick film has a honeycomb-like network structure. ► A logarithmic temperature dependence of the conductance is verified below 30K. ► The 120nm-thick film has the lowest coercivity.Fe films were deposited on nanochannel Al₂O₃ substrates at 300K by direct current magnetron sputtering with the oblique target. The film thickness is 100nm, 120nm, 175nm and 325nm. All the films consist of granules and grow with a network structure. The network structure is formed by granule connection. The granule consists of many fine grains. The granule size increases with increasing film thickness. The transverse width of the granule gradually widens along the film growing direction. The 120nm-thick film has a honeycomb-like network structure. The network films have a resistivity of about 7×10⁻⁵Ωm. A temperature dependence of the resistivity within 1.5–200K reveals that the Fe network films exhibit a minimal resistivity at about 30K. A logarithmic temperature dependence of the conductance is verified at temperatures below 30K. The 100nm-thick film exhibits the weakest magnetocrystalline anisotropy and magnetic uniaxial anisotropy. The 120nm-thick film has the lowest coercivity.

Keywords: Fe film; Network structure; Magnetization; Resistivity; Transport property

Characterization and mechanism analysis of N doped TiO₂ with visible light response and its enhanced visible activity by Xiuwen Cheng; Xiujuan Yu; Zipeng Xing (pp. 3244-3248).

► N–TiO₂ was synthesized by addition of ammonia water using a simple sol–gel method. ► The light absorbance edge of N–TiO₂ was shifted to visible light region. ► The separation efficiency of photogenerated charge carriers was improved by N doping. ► The anatase crystallinity was improved by doping with N. ► The activity enhanced-mechanism was discussed in detail.Nitrogen doped TiO₂ nanoparticles were synthesized through a hydrolysis–precipitation process using ammonia water as the doping species. The resulting materials were characterized by XRD, DRS, SPS, XPS and FT-IR. Further, the activity enhanced-mechanism was discussed in detail. XRD results showed that doping with nitrogen could effectively retard the phase transformation of TiO₂ from anatase to rutile and increase the anatase crystallinity. DRS and SPS results indicated that the light absorbance edge of nitrogen doped TiO₂ nanoparticle was obviously red-shifted to visible light region and the separation rates of photogenerated charge carriers were greatly improved, respectively. XPS and FT-IR analysis implied that the contents of surface hydroxyl groups were improved significantly and the VBM (valance bond maximum) of O2p was 2.3eV. Under the visible light irradiation with 120min, a 65.3% degradation rate of phenol could be achieved. The photocatalytic activity of nitrogen doped TiO₂ was 2.08 and 1.97 times than that of pure TiO₂ and P25 TiO₂, respectively. The enhanced visible light activity was attributed to the well anatase crystallinity, small crystallite size, intense light absorbance edge in visible region, more content of surface hydroxyl groups and high separation efficiency of photogenerated charge carriers.

Keywords: Hydrolysis–precipitation process; Photocatalytic; N doped; TiO; ₂; Phenol

The formation of neodymium conversion coating and the influence of post-treatment by Xiufang Cui; Guo Jin; Yuyun Yang; Erbao Liu; Lili Lin; Jinggao Zhong (pp. 3249-3254).

► The formation of neodymium-based conversion coating is investigated. ► The influence of post-treatment on neodymium conversion coating is studied. ► The coating post-treated is rich in OH⁻ and PO₄³⁺. ► The post-treatment can effectually improve the corrosion resistance of the coating.In this paper, neodymium-based conversion coating is used as a substitute for toxic chromate conversion coating on AZ91D magnesium alloys. Its formation and growth were observed via SEM, EDS, XPS, electrochemical tests and weighting experiment. The influence of post-treatment on neodymium conversion coating was measured by FTIR and electrochemical experiments in terms of morphology, component, surface functional group and corrosion resistance. The dissolution of matrix and the deposition of neodymium/magnesium oxides compete with each other in initial time. Then the deposition of neodymium oxides dominates the process. Compact coating is obtained after 20min immersion and it is mainly made of neodymium oxides and a small amount of magnesium oxides/hydroxides. The coating post-treated is rich in OH⁻ and PO₄³⁺. The post-treatment can improve the corrosion resistance of the neodymium conversion coating effectually examined by EIS.

Keywords: Neodymium conversion coating; Formation; Post-treatment; Corrosion

Photoluminescence of undoped and Ce-doped SnO₂ thin films deposited by sol–gel-dip-coating method by Shuai Chen; Xiaoru Zhao; Haiyan Xie; Jinming Liu; Libing Duan; Xiaojun Ba; Jianlin Zhao (pp. 3255-3259).

► A violet photoluminescence peak was observed in undoped SnO₂, which is related to the defects. ► An additional blue photoluminescence peak appeared only after introducing Ce³⁺ ions into the SnO₂ host. ► The luminescence of the Ce-doped thin films is related to the doping concentration and the annealing temperature.The undoped and Ce-doped SnO₂ thin films synthesized by a simple sol–gel-dip-coating method on glass substrates were investigated by means of X-ray diffractometer, visible spectrophotometer and photoluminescence (PL) spectroscopy. The samples were polycrystalline thin films with rutile structure of undoped SnO₂. A violet PL peak was observed in undoped SnO₂ at room temperatures, while a blue PL peak appeared only after introducing Ce³⁺ ions into the SnO₂ host. The effects of Ce doping concentration and heat-treatment temperature on PL of the films were further studied, and the luminescence mechanism was also discussed.

Keywords: Thin films; Sol–gel; Photoluminescence

Anodization formation of through-hole nanoporous layers on Ti_xNb1−_x ( x=0.3–0.7) alloys in nitric acid electrolytes by Fei Hu; Xin Lin; ShengLi Zhu; XianJin Yang; ZhenDuo Cui (pp. 3260-3263).

Display Omitted► The production of self-organized, through-hole, and ordered nanoporous layers on Ti_xNb1−_x ( x=0.3–0.7) alloys. ► The distinctive exothermal and fast anodization process in nitric acid electrolytes. ► The tunable pore distribution by alloys composition and electrolyte concentration.Self-organized, through-hole, and ordered nanoporous array layers are obtained by anodizing Ti_xNb1−_x ( x=0.3–0.7) alloys in nitric acid electrolytes by a rapid, direct, and exothermal method. The TiNb oxide nanoporous films consist of straight and uniform pores of diameters 10–30nm, and the back side has uniform pores of diameters 20–60nm. The pore spacing increases with increasing Nb content and nitric acid concentration. The process is remarkably reliable and reproducible.

Keywords: TiNb; Rapid anodization; Nanoporous array; Fluoride-free

Influence of the ion type on the ion beam mixing of Cr/Al interfaces by A. Arranz (pp. 3264-3268).

► XPS has been used to study the influence of the ion type on the ion beam mixing of Cr/Al interfaces. ► A two stages ion beam mixing kinetics has been found by factor analysis. ► The different energy deposited and sputtering yields per incoming ion, and preferential sputtering effects explain the differences observed between Ar⁺ and He⁺ beam mixing. ► Experimental results have been compared with Monte Carlo TRIDYN simulations.The room temperature ion beam mixing (IBM) of Cr/Al interfaces by 3keV Ar⁺ and He⁺ ions has been carried out in order to study the influence of the ion type on the IBM process. A two stages IBM kinetics has been found by application of factor analysis to X-ray photoelectron spectroscopy data. The first stage is characterized by a strong decrease of the metallic Cr species concentration associated with sputtering and formation of a nearly stoichiometric chromium aluminide, CrAl. The CrAl related species concentration reaches a maximum at the end of the first stage, slowly decreasing subsequently during the second stage because of sputtering. The differences observed between the final ion dose and maximum CrAl species concentration at the end of the first stage between Ar⁺ and He⁺ IBM have been explained as due to the different sputtering yields and energy deposited per incoming ion. Likewise, the difference observed in the stoichiometry of the CrAl compound formed has been associated with Cr preferential sputtering effects taking place during Ar⁺ IBM. The disagreement between experimental results and Monte Carlo TRIDYN simulations suggests that radiation-enhanced diffusion processes contribute to the low energy Ar⁺ and He⁺ IBM of Cr/Al interfaces at room temperature, especially when He⁺ is used.

Keywords: Chromium aluminide; Ion beam mixing; X-ray photoelectron spectroscopy; Factor analysis; Coatings

Surface, dynamic and structural properties of liquid Al–Ti alloys by R. Novakovic; D. Giuranno; E. Ricci; A. Tuissi; R. Wunderlich; H.-J. Fecht; I. Egry (pp. 3269-3275).

► Modelling is useful to predict lacking thermophysical property data of Al–Ti melts. ► New experimental surface tension data on the Al₉₈Ti₂ alloy. ► Calculation of the surface properties by Complex Formation Model (CFM). ► Effects of the short range order on the mixing of Al–Ti liquid alloys can be deduced. ► Prediction of structure can compensate the lack of structural data of Al–Ti melts.The systems containing highly reactive element such as Ti are the most difficult to be determined experimentally and therefore, it is often necessary to estimate the missing values by theoretical models. The thermodynamic data of the Al–Ti system are scarce, its phase diagram is still incomplete and there are very few data on the thermophysical properties of Al–Ti melts. The study on surface, dynamic and static structural properties of liquid Al–Ti alloys has been carried out within the framework of the Compound Formation Model. In spite of the experimental difficulties, the surface tension of liquid Al–2at.%Ti alloy has been measured over a temperature range by the pinned drop method.

Keywords: Al–Ti; Thermodynamics and statistical mechanics; Surface tension; Surface segregation; Short range ordering

Effect of surface conditioning on the flowability of Ti6Al7Nb powder for selective laser melting applications by T. Marcu; M. Todea; I. Gligor; P. Berce; C. Popa (pp. 3276-3282).

► Surface conditioning improved the flowability of Ti6Al7Nb powder for SLM. ► Surface conditioning consisted of a simple heat treatment in air at 500°C for 1h. ► Free-flowing powders had higher amount of Al₂O₃ in the surface TiO₂ layer. ► Lattice and fully dense samples were produced from conditioned powder by SLM. ► Conditioning did not affect the microstructure of the manufactured structures.Porous metallic implants have been developed to provide a good implant–tissue mechanical attachment and an as close as possible elastic modulus to that of human bone, by the means of a proper porosity. A viable manufacturing technology for personalized implants is rapid prototyping (RP), which employs fine feeding powders which usually display a poor flow behaviour.In the present work, the required flowability of Ti6Al7Nb powder aimed for selective laser melting (SLM) applications was improved by applying a simple heat treatment in air, at temperatures higher than 500°C. As flowability depends on the powder surface condition, the surface chemical composition before and after heat treatment was characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analysis. The results indicated that the amount of basic and acidic –OH groups is almost the same for powders treated at 400°C, which do not flow, and powders treated at 500°C, which display flowability. An increase of the Al₂O₃ amount in the TiO₂-based surface layer on the powder particles with the treatment temperature was noticed. Based on the results, the temperature of 500°C was selected for the further research. The conditioned powder displayed a very good technological behaviour, being successfully used for obtaining specimens with both cellular and fully dense structures through SLM. The microstructure of the manufactured samples, characterized by optical microscopy and scanning electron microscopy (SEM), has shown mainly α′ martensite, with columnar grains.

Keywords: Titanium alloys; Selective laser melting; Heat treatment; Surface characterization; Microstructure

Influence of Tm-doping on microstructure and luminescence behavior of barium strontium titanate thick films by Jingyang Wang; Tianjin Zhang; Ruikun Pan; Zhijun Ma; Jinzhao Wang (pp. 3283-3288).

► Tm-doped Ba_0.8Sr_0.2TiO₃ thick films have been prepared by screen-printing method. ► Two Tm-related emission bands are observed in Tm-doped BST thick films. ► The Tm-related red emission reaches the maximum at 0.2mol% Tm³⁺ concentration.Tm-doped Ba_0.8Sr_0.2TiO₃ thick films were prepared by the screen-printing technique on the alumina substrate. The microstructure of the Tm-doped BST thick films was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy, respectively. All the samples showed a typical perovskite polycrystalline structure when sintered at 1260°C. The substitution behavior of Tm³⁺ ion in BST was found to change with increasing the Tm³⁺ concentration. The observed Tm-related red emission reaches the maximum at 0.2mol% Tm³⁺ concentration. The effects of concentration quenching on the luminescence intensity were discussed.

Keywords: BST; Tm-doped; Thick films; Microstructure; Luminescence

Physico-chemical properties of Pd nanoparticles produced by Pulsed Laser Ablation in different organic solvents by Gabriele Cristoforetti; Emanuela Pitzalis; Roberto Spiniello; Randa Ishak; Francesco Giammanco; Maurizio Muniz-Miranda; Stefano Caporali (pp. 3289-3297).

► Colloids were prepared in acetone, ethanol, 2-propanol, toluene and n-hexane. ► Instrumental parameters and role of solvent were investigated. ► Colloids were characterized by UV–vis, TEM-EDS, XPS and micro-Raman. ► Acetone and alcohols gave spheroidal, stable and crystalline Pd NP. ► Unstable colloids, carbon-rich material, were obtained in toluene and n-hexane.Palladium nanoparticles are arousing an increasing interest because of their strong activity in heterogeneous catalysis in a wide range of reactions. Driven by the interest of producing Pd nanoparticles to be deposited for catalysis over hydrophobic supports, we investigated their synthesis via Pulsed Laser Ablation in Liquid in several organic solvents, as acetone, ethanol, 2-propanol, toluene, n-hexane. The colloids were produced by using a Nd:YAG ns laser and without the addition of surfactant agents. The morphology, composition, stability and oxidation state of the obtained nanoparticles were investigated by TEM-EDS analysis, UV–vis spectroscopy, X-ray Photoelectron Spectroscopy and micro-Raman spectroscopy. The results evidence that the nature of the solvent influences both the yield and the physico-chemical properties of the produced nanoparticles. While in acetone and alcohols spheroidal, non aggregated and stable particles are obtained, in case of toluene and n-hexane few unstable particles surrounded by a gel-like material are produced. Raman/XPS measurements suggest the presence of amorphous or graphitic carbon onto crystalline Pd nanoparticles, which could have hindered their growth and determined the observed smaller sizes if compared to nanoparticles produced in water. The stability of Pd colloids obtained in acetone and alcohols was attributed to adsorbed anions like enolates or alcoholates; non polar solvents like toluene and n-hexane, unable to give rise to adsorbed anionic species, cannot provide any stabilization to the palladium nanoparticles. XPS analyses also evidenced a partial oxidation of particles surface, with a ratio Pd²⁺:Pd⁰ of 1:2.5 and 1:4 in acetone and ethanol, respectively.

Keywords: Pulsed Laser Ablation in Liquid; Palladium nanoparticles; Organic solvents; Nanoparticles synthesis

A periodic DFT study on binding of Pd, Pt and Au on the anatase TiO₂ (001) surface and adsorption of CO on the TiO₂ surface-supported Pd, Pt and Au by Raina Wanbayor; Vithaya Ruangpornvisuti (pp. 3298-3301).

Display Omitted► Periodic DFT binding energies of Pd, Pt and Au on anatase TiO₂ (001) surface are reported. ► The relative binding abilities of the Au, Pt and Pd metal atoms on anatase TiO₂ (001) surface are in order: Pt≫Au≈Pd. ► Adsorption energies of CO on TiO₂ surface-supported Pd, Pt and Au with the surface coverage of 0.5 ML were obtained. ► The relative adsorption abilities of CO on TiO₂ (001)-supported Pd, Pt and Au for the surface coverage of 0.5 ML are in order: Pt>Au>Pd.Binding of Pd, Pt and Au on the anatase TiO₂ (001) surface and adsorption of CO on the TiO₂ (001)-supported Pd, Pt and Au were studied by means of periodic density functional theory calculations. The relative binding abilities of Pd, Pt and Au on the anatase TiO₂ (001) surface are in order: Pt≫Au≈Pd. The relative adsorption abilities of CO on the TiO₂ (001)-supported Pd, Pt and Au for the surface coverage equal to 0.5 ML are in order: Pt>Au>Pd of which adsorption energies are −15.98, −12.97 and −3.53kcal/mol, respectively.

Keywords: Binding energy; Adsorption energy; TiO; ₂; supported Pd, Pt and Au; Anatase TiO; ₂; (0; 0; 1); CO adsorption; Periodic DFT

Structural, electrical and optical properties of ZnO:AlF₃ thin films deposited by RF magnetron sputtering by Tien-Chai Lin; Wen-Chang Huang; Chin-Hung Liu; Shy-Chou Chang (pp. 3302-3308).

► Co-doping with Al and F on the ZnO thin films. ► AlF₃ target was used to provide doping source. ► High carrier concentration, 4.06×10²⁰cm⁻³ was reached in the ZnO:AlF₃ film. ► The high carrier concentration was both due to O⁻² replaced by F⁻¹ and Zn²⁺ replaced by Al³⁺.Both the effects of RF power and thermal annealing temperature on AlF₃ doped ZnO thin films were discussed in the paper. Structural, electrical, and optical characterizations were used to evaluate the properties of the film. Results showed that the growth of c-axial preferential ZnO (002) was not disturbed by the variations of RF powers applied on the AlF₃ target. The optical bandgap of the film increased from 3.28 to 3.74eV as the power increased from 0 to 125W. A high quality ZnO:AlF₃ film was obtained at the power ratio of 100W/75W applied on ZnO/AlF₃. This film showed a low resistivity of 3.60×10⁻²Ωcm, carrier concentration of 4.06×10²⁰cm⁻³, mobility of 0.62cm²/Vs, and transmittance of 85% in the visible region. The small addition of fluorine and aluminum addition to the ZnO film resulted in the increase of carrier concentration as well as increase in Hall mobility. These effects were due to the addition of fluorine which caused the ionized point defects to be removed. An excessive addition of fluorine and aluminum to the ZnO increased grain boundary scattering, resulting in a decrease of Hall mobility. The crystallinity and Hall mobility of the films were further improved after thermal annealing.

Keywords: ZnO; Crystal structure; X-ray diffraction; Hall mobility

Silver modified platinum surface/H⁺ conducting Nafion membrane for cathodic reduction of nitrate ions by M.A. Hasnat; N. Ahamad; S.M. Nizam Uddin; Norita Mohamed (pp. 3309-3314).

► Catalytic effects are observed when Ag particles are deposited on Pt film. ► The reduction process is diffusion controlled and follows first order kinetics. ► The reactivity and selectivity are controlled by potential. ► Decrease of roughness causes deactivation of the performance.Electrocatalytic reduction of NO₃⁻ was performed at an Ag modified Pt electrodes supported on a H⁺ conducting Nafion-117 polymer electrolyte. The cyclic voltammetric and electrolysis experiments showed that the reduction process was a two-electron transfer reaction. The conversion of nitrate to nitrite follows first order kinetics. Controlled potential electrolysis experiments revealed that the highest reduction rate ( k₁; 95.1×10⁻³min⁻¹) could be obtained at −1.3V versus Ag/AgCl (std. KCl) reference electrode. Meanwhile, substantial nitrate removal (ca. 89%) could be attained by a flow system when the flow rate is as low as 0.1mlmin⁻¹. The Ag particles on the Pt film were a in polycrystalline state having roughness value of 0.45μm, which was reduced to 0.30μm after 270min of undergoing electrolysis.

Keywords: Nitrate reduction; Voltammetry; Electrolysis; Rate constant; Selectivity

Surfactant modified MgFe₂O₄ nanopowders by reverse micelle processing: Effect of water to surfactant ratio ( R) on the particle size and magnetic property by J. Chandradass; Arvind H. Jadhav; Hern Kim (pp. 3315-3320).

► Surfactant modified MgFe₂O₄ nanoparticles was prepared by reverse micelle process. ► The average particle size increases with increase in water to surfactant ratio(R).► The highest saturation magnetization value of 40.05emu/g at R=12 was obtained.Nanoparticles of surfactant modified MgFe₂O₄ have been synthesized by reverse micelle processing using tertiary system of heptane/Igepal CO 520/H₂O. The effect of water to surfactant ratio on the particle size and magnetic property has been studied. X-ray diffraction analysis confirms that MgFe₂O₄ nanoparticles are crystalline in nature with cubic spinel structure. The average particle size increases with increase in water to surfactant ratio. The Fourier transform infrared (FTIR) analysis confirms that the surface of MgFe₂O₄ nanoparticles was coated with surfactants. The saturation magnetization ranged from 14.4 to 40.05emu/g was measured by Superconducting Quantum Interference Device Magnetometry (SQUID).

Keywords: Nanopowders; Reverse micelle; Crystal structure; Superparamagnetism

Study on calcination of bi-layered films produced by anodizing iron in dimethyl sulfoxide electrolyte by Arūnas Jagminas; Vaclovas Klimas; Kęstutis Mažeika; Sigitas Mickevičius; Saulius Balakauskas (pp. 3321-3327).

Display Omitted► Calcination of thick bi-layered films onto the iron surface is studied. ► A novel dimethyl sulfoxide electrolyte with H₂SiF₆ is applied for nanoporous anodic film formation. ► Much longer heating time is required to transform such film material to hematite.Research on well adherent, thick and nanoporous oxide film formation onto the metal substrates underwent a major burst throughout the last decade. In the current study, thick bi-layered films produced onto a pure iron surface by anodizing way in dimethyl sulfoxide (DMSO) electrolyte containing silica hexafluoride acid have been investigated upon the annealing in air. Compositional, phase and structural transformations of the film material to hematite, α-Fe₂O₃, were studied using Mössbauer spectroscopy at room to cryogenic temperatures, thermogravimetry (TG), differential thermal analysis (DTA), photoemission spectroscopy, scanning electron microscopy (SEM), and wave dispersive X-ray spectroscopy (WDX). Experimental findings indicated that much longer heating in air is required for these films to be fully transformed to hematite. This effect is linked here with the complex nature of DMSO films. Based on the combined WDX, photoemission and Mössbauer spectroscopy results, the transformations taken place during calcination of such amorphous films by heat-treatment in air to crystalline hematite have been determined. Investigations on the calcination effects of thick iron anodic films reported here offer opportunities for both fundamental research and practical applications.

Keywords: PACS; 61.43Gt; 81.05.z; 81.40.G; 82.80.E; 81.70.PNanotechnology; Iron anodizing; Hematite; Thermal decomposition; Characterization

The stability boundary of group-III transition metal diboride ScB₂ (0001) surfaces by Hui Zhao; Na Qin (pp. 3328-3330).

Experimental observations and theoretical investigations exhibit that a group-IV(V) transition metal diboride (0001) surface is terminated with a 1×1 TM(B) layer. As to a group-III transition metal diboride, we have investigated the stability boundary of ScB₂ (0001) surfaces using first principles total energy plane-wave pseudopotential method based on density functional theory. The Mulliken charge population analysis shows that Sc atoms in the second layer cannot provide B atoms in the first layer with sufficient electrons to form a complete graphene-like boron layer. We also found that the charge transfer between the first and the second layer for the B-terminated surface is more than that for Sc-terminated surface. It elucidates the reason that the outermost interlayer spacing contract more strongly in the B-terminated surface than in the Sc-terminated surface. The surface energies of both terminated ScB₂ (0001) surfaces as a function of the chemical potential of B are also calculated to check the relative stability of the two surface structures.

Keywords: Scandium diboride; Surface; First-principles; Mulliken population; Surface energy

Erratum to “Study on phase separation in a-SiO_x for Si nanocrystal formation through the correlation of photoluminescence with structural and optical properties” [Appl. Surf. Sci. 257 (2011) 6145–6151] by Jie Gan; Qian Li; Zhigao Hu; Wenlei Yu; Kun Gao; Jian Sun; Ning Xu; Jiada Wu (pp. 3331-3331).

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Applied Surface Science (v.258, #7)