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Applied Surface Science (v.265, #)

Editorial Board (pp. ii).

Morphology and growth of hafnium silicide on Si(111) by A. Beimborn; E. Henschel; C. Westphal (pp. 1-3).

► The evaporation and thermal annealing of hafnium on Si leads to silicide nano wires. ► The size of these wires like structures increases with increasing temperature. ► The number of wires decreases with increasing temperature. ► The islands grow along the tree main directions of the (111) surface.The structure and growth of hafnium silicide on Si(111) were studied by scanning tunneling microscopy (STM). Hafnium was deposited by electron beam evaporation onto a clean Si(111) surface under UHV-conditions. The sample was heated in several steps up to 900°C. Upon annealing a growth of elongated nanosized structures was observed. These hafnium silicide islands were found to grow along three main directions, aligned to the symmetry of the (111) surface. As a result, we found that the morphology of these silicide islands is affected by the annealing temperature. Overlapping elongated structures form upon annealing at 450°C. First isolated islands were found at 650°C. The distribution of these islands is equivalent for the three different main directions of the (111) surface. In comparison to the homogeneous distribution the growth of length, width, and height of the stripes starts at different temperatures for the different orientated stripes. With increasing island volume the number density of islands decreases. An analysis of the mean coverage was performed which indicated a possible decrease of the amount of hafnium on the surface. It was found that step edges have no apparent influence on the island distribution.

Keywords: PACS; 68.37.Ef; 68.43.Fg; 68.43.HnHigh-k; Si(1; 1; 1); Hafnium; STM

Fabrication, characterization, and application in nanoenergetic materials of uncracked nano porous silicon thick films by Shouxu Wang; Ruiqi Shen; Cheng Yang; Yinghua Ye; Yan Hu; Chuangxin Li (pp. 4-9).

The uncracked PS thick film is realized by our developed method, and the stable combustion of PS nEMs is achieved.Display Omitted► An improved technique is realized to fabricate uncracked nano porous silicon (PS) thick film, and its cracking mechanism is discussed in order to avoid the crack of PS thick film. ► The characterization and application of uncracked nano PS thick films are reported, and the fabrication of porous silicon nanoenergetic materials (PS nEMs) is fabricated. ► The combustion of PS nEMs is realized when it's ignited by single pulse laser and its combustion is self-sustained.The porous silicon (PS) film has gained increasing attention in recent years as advanced nanoenergetic materials (nEMs). A simple fabrication method to prepare uncracked PS thick films was successfully realized with precisely controlled electrochemical etching, and the relationship between the current density and the concentration of electrolytes was found in its fabrication. Additionally, the capillary stresses resulted from the liquids in nanopores of PS films was another factor resulted in its crack. The nanopores composed of uncracked PS thick films distributed regularly and their diameters ranged from 2nm to 6nm. Its S_a (average roughness) of PS film surface was 6.53nm, and its thickness ranged from 102.41μm to 205.75μm. The specific surface area was 587m²/g and the average diameter of nanopores was 4.3nm. The PS film was found to be monocrystal and it was same as the substrate. The crack mechanism of PS films was discussed: the porous structure reduced the strength of PS films comparing the silicon bulk and the capillary effect hastened the crack of PS films. PS films filling with sodium percholorate in nanopores were ignited by laser and the stable combustion showed that they were advantageous to be applied as micro-electromechanical systems (MEMS) compatible devices, such as silicon-based chips of mircothruster and microigniter.

Keywords: Porous silicon; Fabrication; Nanostructure; Nanopores; nEMs

High temperature degradation behavior of sputtered nanostructured Co–Al coatings on superalloy by Atikur Rahman; R. Jayaganthan; Ramesh Chandra; R. Ambardar (pp. 10-23).

► High temperature oxidation of nanostructured Co–Al coatings has been investigated. ► Oxidation kinetics of the coatings is very slow due to protective scale formation. ► The Co–Al coatings exhibit improved oxidation resistance and scale-metal adherence.Microstructure and cyclic high temperature oxidation behavior of nanostructured Co–Al coatings on Superni-718 substrate have been investigated. Cyclic high temperature oxidation tests were conducted on uncoated and coated samples at peak temperatures of 800°C and 900°C for up to 100 thermal cycles between the peak and room temperatures. The results showed that bare substrate has higher oxidation resistance at 800°C as compared to 900°C and coated sample has slightly higher oxidation resistance at 900°C. The external scale of both coated sample exhibited good spallation resistance during cyclic oxidation testing at both temperatures. The improvement in oxide scale spallation resistance is believed to be related to the fine-grained structure of the coating. Nanostructured Co–Al coatings on Superni-718 substrate were deposited by DC/RF magnetron sputtering. FE-SEM/EDS and XRD were used to characterize the morphology and formation of different phases in the coatings, respectively. The Co–Al coating on superalloy substrate showed better performance of cyclic high temperature oxidation resistance due to its possession of β-CoAl phase as Al reservoir and the formation of Al₂O₃ and spinel phases such as CoCr₂O₄ and CoAl₂O₄ in the scale. The oxidation results confirmed an improved oxidation resistance of the Co–Al coating on superalloy as compared to bare substrate up to 100 cycles.

Keywords: Sputter deposition; Nanostructured Co–Al coatings; Cyclic high temperature; Oxidation; Protective oxide scale; Scale spallation

ZnO nanowire-based glucose biosensors with different coupling agents by Juneui Jung; Sangwoo Lim (pp. 24-29).

► Fabrication of ZnO nanowire-based glucose biosensors using different coupling agents. ► Highest sensitivity for (3-aminopropyl)methyldiethoxysilane-treated biosensor. ► Larger amount of glucose oxidase and lower electron transfer resistance for (3-aminopropyl)methyldiethoxysilane-treated biosensor.ZnO-nanowire-based glucose biosensors were fabricated by immobilizing glucose oxidase (GOx) onto a linker attached to ZnO nanowires. Different coupling agents were used, namely (3-aminopropyl)trimethoxysilane (APTMS), (3-aminopropyl)triethoxysilane (APTES), and (3-aminopropyl)methyldiethoxysilane (APS), to increase the affinity of GOx binding to ZnO nanowires. The amount of GOx immobilized on the ZnO nanowires, the performance, sensitivity, and Michaelis–Menten constant of each biosensor, and the electron transfer resistance through the biosensor were all measured in order to investigate the effect of the coupling agent on the ZnO nanowire-based biosensor. Among the different biosensors, the APS-treated biosensor had the highest sensitivity (17.72μAcm⁻²mM⁻¹) and the lowest Michaelis–Menten constant (1.37mM). Since APS-treated ZnO nanowires showed the largest number of CN groups and the lowest electron transfer resistance through the biosensor, we concluded that these properties were the key factors in the performance of APS-treated glucose biosensors.

Keywords: ZnO nanowire; Surface; Immobilization; Biosensors

Characterization of hydroxyapatite coating by pulse laser deposition technique on stainless steel 316 L by varying laser energy by Himanshu Khandelwal; Gurbhinder Singh; Khelendra Agrawal; Satya Prakash; R.D. Agarwal (pp. 30-35).

► Hydroxyapatite coating was successfully deposited on stainless steel substrate by pulse laser deposition at different energy levels (i.e. 300mJ and 500mJ, respectively). ► Variation in laser energy affects the surface characteristic of hydroxyapatite coating (particle size, surface roughness, uniformity, Ca/P ratio). ► Laser energy between 300mJ and 500mJ is the optimal choice for obtaining ideal Ca/P ratio.Hydroxyapatite is an attractive biomaterial mainly used in bone and tooth implants because it closely resembles human tooth and bone mineral and has proven to be biologically compatible with these tissues. In spite of this advantage of hydroxyapatite it has also certain limitation like inferior mechanical properties which do not make it suitable for long term load bearing applications; hence a lot of research is going on in the development of hydroxyapatite coating over various metallic implants. These metallic implants have good biocompatibility and mechanical properties. The aim of the present work is to deposit hydroxyapatite coating over stainless steel grade 316 L by pulse laser deposition technique by varying laser energy. To know the effect of this variation, the coatings were than characterized in detail by X-ray diffraction, finite emission-scanning electron microscope, atomic force microscope and energy dispersive X-ray spectroscopy.

Keywords: Pulse laser deposition; Hydroxyapatite; Coatings; Thin films; Laser energy; Stainless steel

A direct synthesis of B-doped TiO₂ and its photocatalytic performance on degradation of RhB by Li Liang; Yang Yulin; Liu Xinrong; Fan Ruiqing; Shi Yan; Li Shuo; Zhang Lingyun; Fan Xiao; Tang Pengxiao; Xu Rui; Zhang Wenzhi; Wang Yazhen; Ma Liqun (pp. 36-40).

Display Omitted► B-doped TiO₂ was synthesized by a simple direct hydrolyzation. ► We evaluated the photocatlytic activity of B-doped TiO₂ under simulate sunlight. ► SPV technique was utilized to study the change of physical and chemical properties by introducing boron.B-doped TiO₂ was synthesized by a direct hydrolyzation of n-tetrabutyl titanate in a solution of boric acid, and was treated by hydro-thermal synthesis. The powder was characterized by X-ray diffraction (XRD), FT-IR, scanning and transmission electron microscopy (SEM and TEM), surface photoviolet spectra, UV–visible absorption spectra and X-ray photoelectron spectroscopy (XPS). Rhodamine B (RhB) degradation was used as a probe reaction to evaluate the photocatalytic activity of B-doped TiO₂ under simulate sunlight, and excellent photocatalytic performance was achieved.

Keywords: B-doped TiO; ₂; Photodegradation; RhB; SPV

Novel doped hydroxyapatite thin films obtained by pulsed laser deposition by L. Duta; F.N. Oktar; G.E. Stan; G. Popescu-Pelin; N. Serban; C. Luculescu; I.N. Mihailescu (pp. 41-49).

► HA coatings synthesized by pulsed laser deposition. ► Comparative study of commercial vs. animal origin materials. ► HA coatings of animal origin were rougher and more adherent to substrates. ► Animal origin films can be considered as promising candidates for implant coatings.We report on the synthesis of novel ovine and bovine derived hydroxyapatite thin films on titanium substrates by pulsed laser deposition for a new generation of implants. The calcination treatment applied to produce the hydroxyapatite powders from ovine/bovine bones was intended to induce crystallization and to prohibit the transmission of diseases.The deposited films were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and energy dispersive X-ray spectroscopy. Pull-off adherence and profilometry measurements were also carried out.X-ray diffraction ascertained the polycrystalline hydroxyapatite nature of the powders and films. Fourier transform infrared spectroscopy evidenced the vibrational bands characteristic to a hydroxyapatite material slightly carbonated. The micrographs of the films showed a uniform distribution of spheroidal particulates with a mean diameter of ∼2μm. Pull-off measurements demonstrated excellent bonding strength values between the hydroxyapatite films and the titanium substrates.Because of their physical–chemical properties and low cost fabrication from renewable resources, we think that these new coating materials could be considered as a prospective competitor to synthetic hydroxyapatite used for implantology applications.

Keywords: Doped hydroxyapatite; Ovine/bovine bones; Highly adherent thin films; Pulsed laser deposition

Surface tension and density of liquid In–Sn–Zn alloys by Janusz Pstruś (pp. 50-59).

► Surface tension of In–Sn–Zn alloy was studied with MBP method. ► Surface tension is independent on In concentration. ► Surface tension increases with Zn concentration. ► Butler model well reproduces experiment at high temperatures.Using the dilatometric method, measurements of the density of liquid alloys of the ternary system In–Sn–Zn in four sections with a constant ratio Sn:In=24:1, 3:1, 1:1, 1:3, for various Zn additions (5, 10, 14, 20, 3 5, 50 and 75at.% Zn) were performed at the temperature ranges of 500–1150K.Density decreases linearly for all compositions. The molar volume calculated from density data exhibits close to ideal dependence on composition.Measurements of the surface tension of liquid alloys have been conducted using the method of maximum pressure in the gas bubbles. There were observed linear dependences on temperature with a negative gradients d σ/d T. Generally, with two exceptions, there was observed the increase of surface tension with increasing content of zinc.Using the Butler's model, the surface tension isotherms were calculated for temperatures T=673 and 1073K. Calculations show that only for high temperatures and for low content of zinc (up to about 35at.%), the modeling is in very good agreement with experiment. Using the mentioned model, the composition of the surface phase was defined at two temperatures T=673 and 973K. Regardless of the temperature and of the defined section, the composition of the bulk is very different in comparison with the composition of the surface.

Keywords: Surface tension; Surface composition; Density; In–Sn–Zn alloys; Butler model; Pb-free

Synthesis and characterization of Ti–Si–C–N nanocomposite coatings prepared by a filtered vacuum arc method by Elangovan Thangavel; Seunghun Lee; Kee-Seok Nam; Jong-Kuk Kim; Do-Geun Kim (pp. 60-65).

► Preparation method was used as filtered vacuum arc (FVA) deposition. ► Ternary coating obtained by using single carbon source with TMS gas. ► Detailed discussion of chemical nature for these coating by using XPS.Ti–Si–C–N nanocomposite coatings were synthesized by a filtered vacuum arc (FVA) technique. A metal organic precursor, tetramethylsilane (TMS), was used as a source for silicon and carbon to deposit the Ti–Si–C–N nanocomposite coating with a Ti cathode source. The chemical and microstructural properties of the as-deposited coatings were systematically investigated using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Nanoindentation and scratch tests were carried out to evaluate the mechanical and adhesion properties of the coatings. From the XPS analysis, it was found that the Si content in the coating increased from 2 to 16at.% as the TMS flow rate was increased from 5 to 20sccm. The TEM analysis clearly demonstrated that the coatings were composed of crystalline TiCN along with amorphous Si₃N₄ as a secondary phase. From the XRD results, it was found that the crystallite size of TiCN increased with increasing Si content. The microstructure and mechanical properties of the TiSiCN coatings prepared by this method exhibited strong dependencies on the silicon content. A maximum hardness of 49GPa and a coefficient of friction of 0.17 were obtained for the film with a silicon content of 3at.%.

Keywords: Filtered vacuum arc; Nanocomposite; Ti–Si–C–N; TMS

Triple layered core–shell structure with surface fluorinated ZnO-carbon nanotube composites and its electron emission properties by H.Y. Wang; Daniel H.C. Chua (pp. 66-70).

► The effects of CF₄ plasma on ZnO-CNT core–shell structures were studied. ► ZnO was effective in protecting the aligned CNTs core for as long as 30min of plasma etching. ► SEM showed the surface morphology was nearly similar between pristine, 2min and 30min plasma etched specimens. ► F was observed to displace O in ZnO. ► This is the first report of an ultra long plasma etch of fluorine onto ZnO surface.Core-shelled structures such as zinc oxide (ZnO) on carbon nanotubes (CNTs) give rise to interesting material properties. In this work, a triple-layered core–shell–shell structure is presented where the effects of fluorine (F) incorporation on the outmost shell of the ZnO-CNT structure are studied. The samples prepared ranged from a short 2min to a 30min immersion in carbon tetraflouride (CF₄) plasma. In addition, its effects on the electron emission properties also studied and it is shown that the plasma immersions create thinner field emitters with sharp tiny wrinkles giving rise to more electron emission sites and higher enhancement factor. In addition, X-ray photoelectron spectroscopy measurements showed that F ions replace O in ZnO coatings during immersion process, thus increasing the electrical conductivity and shifts the Fermi level of ZnO upwards. Both physical and electronic effects further contribute to a lower threshold field.

Keywords: ZnO; Carbon nanotubes; Plasma immersion; Fluorine

XPS quantification of the hetero-junction interface energy by Z.S. Ma; Yan Wang; Y.L. Huang; Z.F. Zhou; Y.C. Zhou; Weitao Zheng; Chang Q. Sun (pp. 71-77).

► Quantum entrapment or polarization dictates the performance of dopant, impurity, interface, alloy and compounds. ► Interface bond energy, energy density, and atomic cohesive energy can be determined using XPS and our BOLS theory. ► Presents a new and reliable method for catalyst design and identification. ► Entrapment makes CuPd to be a p-type catalyst and polarization derives AgPd as an n-type catalyst.We present an approach for quantifying the heterogeneous interface bond energy using X-ray photoelectron spectroscopy (XPS). Firstly, from analyzing the XPS core-level shift of the elemental surfaces we obtained the energy levels of an isolated atom and their bulk shifts of the constituent elements for reference; then we measured the energy shifts of the specific energy levels upon interface alloy formation. Subtracting the referential spectrum from that collected from the alloy, we can distil the interface effect on the binding energy. Calibrated based on the energy levels and their bulk shifts derived from elemental surfaces, we can derive the bond energy, energy density, atomic cohesive energy, and free energy at the interface region. This approach has enabled us to clarify the dominance of quantum entrapment at CuPd interface and the dominance of polarization at AgPd and BeW interfaces, as the origin of interface energy change. Developed approach not only enhances the power of XPS but also enables the quantification of the interface energy at the atomic scale that has been an issue of long challenge.

Keywords: Interface; Chemical bond; Binding energy; XPS; Entrapment; Polarization

Synthesis of platinum–polyaniline composite, its evaluation as a performance boosting interphase in the electrode assembly of proton exchange membrane fuel cell by R. Jayasree; K. Mohanraju; L. Cindrella (pp. 78-87).

► Pt–polyaniline composite has been prepared and characterized. ► It has been used as an interlayer in membrane electrode assembly and has been evaluated to boost the performance of the proton exchange membrane fuel cell.Platinum formed on polyaniline (PANi) is used as the interlayer between porous gas diffusion layer and the catalyst layer with the aim to reduce the thickness of the ordinary gas diffusion layer and provide a performance boosting electrostatic layer. The doping tendency of PANi is utilized to incorporate platinum(IV) ion in its matrix by chemisorption followed by its reduction to metallic platinum. Platinum is deposited on polyaniline by a simple wet chemistry method. PANi is prepared by the chemical oxidative polymerization of aniline by ammonium persulphate while Pt deposition on PANi is achieved by a phase transfer method (water–toluene) to yield Pt nanoparticles on PANi. The composite is characterized by XRD, Scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), IR spectroscopy, cyclic voltammetry (CV), AC impedance studies, density and conductivity measurements. The Pt/PANi composite is assessed in the proton exchange membrane fuel cell (PEMFC) using H₂/O₂ gases at ambient pressure. The performance of the PEMFC with Pt/PANi composite interphase on cathode side of the gas diffusion layer (GDL) shows improvement at high current densities which is attributed to the increased capacitative current of Pt/PANi layer in the presence of O₂ thereby improving the kinetics of subsequent reduction of O₂.

Keywords: Polyaniline; Platinum; Composite; Gas diffusion layer coating; Proton exchange membrane fuel cell; Performance characteristics

Advancing and receding angles – Dynamic contact angle measurements on mixed alkyl monolayers by David Polster; Harald Graaf (pp. 88-93).

► Dynamic contact angles are studied on mixed alkyl monolayers bound to silicon. ► Dispersive forces determine the wetting behavior on mixed monolayers. ► No pinning effect of the polar groups in the monolayer can be found. ► Long range interactions are responsible for contact angle hysteresis.Mixtures of 1-decene and methyl-10-undecenoate with different mole fractions were used to prepared mixed monolayers on silicon (100) surfaces. The formed layers were characterized by dynamic contact angle measurements of two different liquids using the dynamic sessile drop method. The advancing and receding contact angles as well the calculated molar wetting free energies decreased with increasing mole fraction of methyl-10-undecenoate. Otherwise the molar dewetting free energies as well as the contact angle hysteresis stay nearly constant. A difference in the wetting and dewetting properties on mixed monolayers is observed, whereby mainly dispersive interactions are responsible for wetting. Furthermore we show that the contact angle hysteresis is independent of surface roughness, surface composition and surface free energy, which indicates that neither surface roughness nor heterogeneities are responsible for this hysteresis. We attribute the hysteresis to interactions between the liquid and the silicon substrate.

Keywords: Dynamic contact angle; Mixed alkyl monolayer; Long range interactions; Dispersive interactions; Polar interactions

Si-rich a-Si1−_xC_x thin films by d.c. magnetron co-sputtering of silicon and silicon carbide: Structural and optical properties by M.A. Ouadfel; A. Keffous; A. Brighet; N. Gabouze; T. Hadjersi; A. Cheriet; M. Kechouane; A. Boukezzata; Y. Boukennous; Y. Belkacem; H. Menari (pp. 94-100).

► A new method Si-rich amorphous silicon carbide thin films have been elaborated. ► Using Si monocrystal and 6H-SiC polycrystal as targets to elaborate a-SiC films. ► Variation number of 6H-SiC has been used to elaborate thin a-Si1−_xC_x:H films. ► The properties of a-Si1−_xC_x:H varies with carbon content x.Si-rich hydrogenated amorphous silicon carbide (a-Si1−_xC_x:H) thin films with different carbon fractions were elaborated by a d.c. magnetron sputtering system. Their structural and optical properties were investigated by UV–visible spectrophotometry, infrared spectroscopy (FTIR), secondary ion mass spectroscopy (SIMS), Raman spectroscopy and photoluminescence (PL). The results show that the increase in the carbon fraction induces an increase in the optical gap ( E_g) up to a maximum value of 2.53eV, corresponding to a carbon fraction ( x) of 0.25, and then E_g decreases to 1.76eV corresponding to a carbon fraction x=0.33.

Keywords: Silicon carbide; Amorphous films; Raman; SIMS

Electrostatic self-assembly: An innovative approach to fabricate novel-structured magnetic liposomes by Wen Zhao; Hong Zhang; TingLi Lu; WenLong Liu; YuFan Ma; Tao Chen (pp. 101-107).

► Novel-structured magnetic liposomes are fabricated by electrostatic self-assembly. ► TEM proves successful fabrication of the novel-structured magnetic liposomes. ► It is a universal approach to prepare these liposomes with tunable size. ► The magnetic liposomes have higher magnetite content and narrow size-distribution. ► In vitro drug release is in accordance with the First-order equation.Electrostatic self-assembly was applied to fabricate novel-structured magnetic liposomes. According to the charge characteristics of the magnetic nanoparticles and the drug-loaded liposomes, magnetic liposomes were fabricated by alternately assembling the suitable polyelectrolytes and magnetic nanoparticles onto the drug-loaded liposomes. TEM photograph provided direct evidence for successful fabrication of the novel-structured magnetic liposomes. It was also found that electrostatic self-assembly is a universal approach to prepare novel-structured magnetic liposomes with tunable size. The reversed phase high performance liquid chromatography (RP-HPLC) method was established to determine the content of the drug in the magnetic liposomes. The content of the magnetic nanoparticles in the magnetic liposomes was determined by UV spectrophotometry, which proved that the content of magnetic nanoparticles in novel-structured magnetic liposomes was higher than in traditional-structured magnetic liposomes. In vitro drug release from the magnetic liposomes was carried out, and fitting of the release curve using Curve Expert software indicated that the in vitro drug release of the magnetic liposomes was in accordance with the First-order equation.

Keywords: Electrostatic self-assembly; Magnetic liposomes; Novel-structured; Content of magnetic nanoparticles; In vitro drug release

Gas sensing enhancement of aluminum-doped ZnO nanovase structure with many gas facile diffusivity paths by Yu Lingmin; Fan Xinhui; Cao Lei; Qi Lijun; Yan Wen (pp. 108-113).

There were a good amount of nanovase nanostructures with a large aperture on the top of it and many short nanorods grew from their surface to generate many holes or channels enough for gas to quickly diffuse from surface to the inside of nanovase.Display Omitted► Al-doped ZnO nanovase structures were synthesized by thermal evaporation method. ► Many gas facile diffusivity paths were generated from nanovase structures. ► Al-doped ZnO nanovases exhibited a better response and selectivity toward ethanol.Al-doped ZnO nanovase structures were synthesized by thermal evaporation method with a fast temperature rise speed. It was found that there were a good amount of nanovase structures with a large aperture on the top of it and many short nanorods grew from their surface to generate many holes or channels enough for gas to quickly diffuse from surface to the inside of nanovase. Gas sensors were fabricated using the Al-doped ZnO nanostructures to examine the responses to 500ppm C₂H₅OH, CO, NH₃, and CH₄ gases. The Al-doped ZnO nanovases exhibited a better response and selectivity toward ethanol as high as 34.1 at 300°C. These results showed that Al-doped ZnO nanovases are highly promising for ethanol sensor applications, as the gas diffusion and mass transportation in sensing materials are significantly enhanced by their unique structures.

Keywords: Nanostructured materials; Oxide materials; Vapor deposition; Gas sensing

Enhanced electrochemical performance of FeS coated by Ag as anode for lithium-ion batteries by Chenchu Dong; Xiaodong Zheng; Bing Huang; Mi Lu (pp. 114-119).

► The FeS and FeS/Ag composite are successfully prepared with a facile electroless deposition method. ► The improved cycling stability is ascribed to the suppression of the volume expansion after Ag coating. ► The improved rate ability is ascribed to the enhanced electronic conductivity of Li₂S after Ag coating.The Ag coated FeS composite is synthesized via a facile electroless deposition method. The as-prepared FeS/Ag composite shows an initial reversible specific capacity of 533.4mAh/g and its capacity retention is 79.1% after 55 cycles at different current densities (from 0.1C to 2C). In contrast, the initial reversible and capacity retention of pristine FeS tested at the same conditions are 425.8mAh/g and 29.1%, respectively. The improved reversible capacity and cyclic performance are ascribed to the coated Ag improving the electronic conductivity of the Li₂S during its charge process and the suppression of the volume change of FeS anode during its discharge process, respectively.

Keywords: Lithium-ion batteries; Anode; FeS

Substitutional adsorption mechanism and controllable magnetic properties of Mn on PbTe(111) surface by H.F. Wu; Y. Wang; Y.H. Lu; Y.P. Feng; P.M. He (pp. 120-123).

► Mn atoms prefer to substitute Pb atoms in the 2nd layer and form a Mn substitutional(3×3)R30° superstructure. ► The magnetic properties of the Mn/PbTe system is strain-dependent. ► An substitutional adsorption mechanism is found for Mn deposition on the PbTe(111) surface.Adsorption of Mn adatom on PbTe(111) surface is investigated by first-principle calculations. A subsurface substitutional adsorption mechanism is found. MnTe bond is stronger and shorter than PbTe bond. This leads to competition. Because of stronger MnTe bond, Mn atoms prefer to be deep into bulk crystal in order to maximum the number of MnTe bond. But the MnTe bonds cannot relax to gain their maximum strength because of the rigidity of the bulk crystal. At the outmost surface layer Mn atoms can relax maximum but the number of MnTe bond is only half of that in bulk. The 2nd layer is the best choice and Mn atoms prefer to form a(3×3)R30° pattern, in well agreement with recent experimental work. More importantly, its magnetic state is strain-dependent and this opens a new avenue to fabricate spintronics and spin caloritronics with a high tunneling magnetothermopower based on PbTe.

Keywords: Magnetic properties; First-principle calculation; Electronic structure; Surface adsorption; Strain dependent

Study of ion beam synthesized nanostructured PbTe surface by Srashti Gupta; D.C. Agarwal; S.K. Tripathi; A. Tripathi; S. Neeleshwar; D.K. Avasthi (pp. 124-129).

► Synthesis of oxygen free PbTe nanostructure by ion beam mixing. ► Atomic force microscopy and scanning electron microscopy are used to characterize the structures. ► Unstable growth and rapid roughening of surface is observed under SHI irradiation. ► The values of exponents obtained from the experiment are different from those predicted by universality classes.Vertically protruding out nano structures of PbTe are synthesized by ion beam mixing of Te/PbO bilayer using 100MeV Ag ions. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) of pristine and irradiated samples are performed to study surface structures. Power spectral density (PSD) spectra of the structures at different fluences have been determined from AFM micrograph. The values of roughness and growth exponent, deduced from PSD, are far from any universality classes. Results distinctly indicate the unstable growth and rapid roughening of surface under swift heavy ion (SHI) bombardment.

Keywords: Thermoelectric material; Lead telluride; Nanostructures; Ion beam irradiation; Power spectral density

Preparation of amorphous and crystalline Ag/TiO₂ nanocomposite thin films by M.M. Viana; N.D.S. Mohallem; D.R. Miquita; K. Balzuweit; E. Silva-Pinto (pp. 130-136).

► Amorphous and crystalline Ag/TiO₂ thin films were prepared by sol–gel process tailored by cooling rate. ► Silver diffusion mechanism into the titania matrix was evaluated. ► Amorphous to anatase–rutile crystalline phase transitions was performed during electron exposition in a TEM. ► Silver concentration plays a role in Ag/TiO₂ thin films plasmon resonance, making them good candidates for optical applications.Ag/TiO₂ thin films have been prepared on glass substrates by the dip-coating technique and sol–gel process using a precursor solution containing titanium alkoxide and silver nitrate in an Ag/Ti atomic ratio of 1:6 and 1:100. These films were annealed at 100°C and 400°C and cooled rapidly to obtain silver nanoparticles dispersed in an amorphous TiO₂ matrix, confirmed by X-ray diffraction (XRD) analyses. Ag/TiO₂ nanocrystalline films were also prepared using slow cooling. Silver nanoparticles coalesced and migrated to the thin film surfaces with increasing annealing temperature as observed by high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) and scanning probe microscopy (SPM). A transmission electron microscope (TEM) was used to induce phase transition in the amorphous matrix into anatase and rutile crystalline phases using a 200kV electron beam. The variation of the Ag/Ti atomic ratio changed the plasmon resonance absorption and band gap values of the Ag/TiO₂ films due to the change in the Ag nanoparticle sizes formed on the surface of films, as verified by UV–vis absorption spectroscopy and spectroscopic ellipsometry.

Keywords: Silver nanocomposite; Titanium dioxide; Ag/TiO; ₂; thin films; Sol–gel process

Electron spectroscopy imaging and surface defect configuration of zinc oxide nanostructures under different annealing ambient by Ling Chuo Ann; Shahrom Mahmud; Siti Khadijah Mohd Bakhori (pp. 137-144).

► Electron spectroscopy imaging revealed non stoichiometry of elemental distribution in ZnO nanopowder. ► Oxygen annealing increased the ratio of O:Zn distribution while nitrogen annealing gave an adverse effect. ► Oxygen and nitrogen annealing provided different effects to the surface conductivity of ZnO pellets. ► Oxygen vacancies were identified as major defect in the annealing process. ► Different stress levels were obtained from different morphologies of ZnO.In this study, electron spectroscopy imaging was used to visualize the elemental distribution of zinc oxide nanopowder. Surface modification in zinc oxide was done through annealing treatment and type of surface defect was also inferred from the electron spectroscopy imaging investigation. The micrographs revealed the non-stoichiometric distribution of the elements in the unannealed samples. Annealing the samples in nitrogen and oxygen ambient at 700°C would alter the density of the elements in the samples as a result of removal or absorption of oxygen. The electrical measurement showed that nitrogen annealing treatment improved surface electrical conductivity, whereas oxygen treatment showed an adverse effect. Observed change in the photoluminescence green emission suggested that oxygen vacancies play a significant role as surface defects. Structural investigation carried out through X-ray diffraction revealed the polycrystalline nature of both zinc oxide samples with hexagonal phase whereby annealing process increased the crystallinity of both zinc oxide specimens. Due to the different morphologies of the two types of zinc oxide nanopowders, X-ray diffraction results showed different stress levels in their structures and the annealing treatment give significant effect to the structural stress. Electron spectroscopy imaging was a useful technique to identify the elemental distribution as well as oxygen defect in zinc oxide nanopowder.

Keywords: Electron spectroscopy imaging; Photoluminescence; Annealing; Ambient; Zinc oxide

Effects of H₂/O₂ mixed gas plasma treatment on electrical and optical property of indium tin oxide by Jun Young Kim; Dong-Min Lee; Jae-Kwan Kim; Su-Hwan Yang; Ji-Myon Lee (pp. 145-148).

► The specific resistivity of ITO was enhanced by H₂+O₂ mixed gas plasma treatment. ► The transmittance was same as that of untreated ITO after plasma treatment. ► The process was carried out at room temperature without any step of post-treatment.This study examined the effects of H₂ and H₂+O₂ mixed gas plasma treatment on the properties of ITO films. The films were deposited on corning glass by RF magnetron sputtering under Ar and Ar/O₂ mixed gas ambient. After a H₂ plasma treatment, the ITO films showed an improved specific resistance due to the formation of oxygen vacancies acting as shallow donors, but showed quenched transmittance due to the formation of agglomerated metals on the surface. After an H₂+O₂ mixed gas plasma treatment, the specific resistance of the film was improved without deteriorating transmittance. The enhanced specific resistance by mixed gas plasma treatment was attributed to the formation of free electrons by the incorporation of H in the lattice.

Keywords: ITO; Surface treatment; Hydrogen; Oxygen; Plasma

A simple and efficient combined AC–DC electrodeposition method for fabrication of highly ordered Au nanowires in AAO template by Zhao Wu; Yunwang Zhang; Kai Du (pp. 149-156).

► The Au nanowire is fabricated in AAO template with barrier layer by combined AC–DC electrodeposition method which is firstly used. ► The fabricated Au nanowires displayed uniform length and the range of current density is much larger comparing with single DC plating. ► The cyclic voltammetry result reveals that the cathodic peak was more negative after AC preplating. ► A new mechanism is proposed and the evidence comes from the TEM result of the two branched Au nanowires.A simple and efficient combined AC–DC electrodeposition method is firstly proposed for preparing metal nanoarrays in this paper. By this method, Au nanowire arrays were successfully deposited into the anodized aluminum oxide (AAO) template. The results showed that the Au nanowires obtained by the combined AC–DC method have uniform length as prepared by AC method and the upper limit of current density of deposition used in the combined AC–DC method can be much higher than that in single DC electrodeposition. The cyclic voltammetry of blank AAO template and the one after AC preplating show that the cathodic peak is more negative after the AC preplating. A new mechanism in terms of AC–DC electrodeposition method based on this sample is proposed. The evidence comes from the result that the branched Au nanowires formed in AC preplating display shorter length and more smaller branches comparing with the one formed in DC plating. It is concluded that AC preplating's filling the branched pores and changing the reactive surface is the essential reason of difference in the combined AC–DC and single DC electrodeposition methods.

Keywords: Au nanowire; Combined AC–DC electrodepositon; AAO template

Domain-selective photochemical reaction on oriented ferroelectric Pb(In_1/2Nb_1/2)O₃–Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ single crystals by Kenny Lau; Yun Liu; Qian Li; Zhenrong Li; Ray L. Withers; Zhuo Xu (pp. 157-161).

.Display Omitted► Crystal orientation influences photodeposition on designated domains. ► Enhanced photodeposition is observed at specific domain boundaries unlike LiNbO₃. ► Tip motion determines which domain boundaries are enhanced when a large switching voltage is used. ► This phenomenon originates from tip injected charges.The domain-selective photoreduction of silver on (001) and (111) oriented 0.25Pb(In_1/2Nb_1/2)O₃–0.44Pb(Mg_1/3Nb_2/3)O₃–0.31PbTiO₃ (PIMNT) ferroelectric single crystals is investigated via piezoresponse force microscopy and Kelvin force microscopy. It is found that the crystallographic orientation as well as the direction and magnitude of the voltage used for domain switching strongly affects the amount and distribution of silver photodeposition. Additionally, the scanning direction of the tip during domain switching significantly affects silver photodeposition at c⁻/c⁺ domain boundaries when a high voltage is applied for domain switching. These phenomena can be explained and thus controlled by polarisation induced band bending, the space charge layer of the ferroelectric crystal and tip induced charge injection during domain switching. This work demonstrates a potential means to achieve an arbitrary spatial distribution of photodeposited metal.

Keywords: Photoreduction; Ferroelectrics; Domain switching; Surface potential

Effect of substrate on surface morphology and photocatalysis of large-scale TiO₂ films by Lorena Lopez; Walid A. Daoud; Dushmanta Dutta; Barbara C. Panther; Terence W. Turney (pp. 162-168).

► TiO₂ large-scale films coated on glass, glass with SiO₂ layer, ceramic and aluminum. ► Substrate effect on surface morphology and photocatalytic activity. ► Nature of substrate affects growth of anatase crystallites. ► Substrate roughness promotes retention of TiO₂ sol. ► Photocatalytic activity of films coated on glass with and without SiO₂ is comparable.Nanostructured TiO₂ films were prepared on a variety of substrates, including acid frosted soda-lime glass, acid frosted soda-lime glass pre-coated with a SiO₂ barrier layer, commercial glazed ceramic tile and 6061 aluminum alloy. For each substrate, the phase and microstructure of the films were determined to be exclusively anatase. However, the growth of the TiO₂ crystallites, the film morphology and thickness varied substantially with substrate. Thermal stress, resulting from the difference in the coefficient of thermal expansion between the substrates and the films, contributed to the formation and propagation of cracks. This was most clearly observed on the films deposited on SiO₂ barrier layer and aluminum. The photocatalytic activity of the TiO₂ films deposited on glass with and without SiO₂ barrier layer, ceramic, and aluminum was studied via UV decolorization of methyl orange in aqueous solution. Complete degradation rapidly occurred on the TiO₂/glass and TiO₂/SiO₂ barrier layer films, but not with the ceramic or metal substrates. It appears that the photocatalytic activity of the films deposited on aluminum and ceramic substrates was affected by the quantity and the size of the anatase crystallites. The aluminum substrate promoted the formation of TiO₂ films with the largest anatase crystallite size, exhibiting a cracked morphology, where as the ceramic substrate resulted in the formation of TiO₂ films with large crystallite size in an island morphology.

Keywords: Large-scale TiO; ₂; films; Substrates; Morphology; Photocatalytic activity

Investigations on opto-electronical properties of DC reactive magnetron sputtered zinc aluminum oxide thin films annealed at different temperatures by B. Rajesh Kumar; T. Subba Rao (pp. 169-175).

► ZAO films were prepared by DC reactive magnetron sputtering method by two individual high purity metallic targets of Zn and Al. ► Sputtering deposition conditions were optimized to exhibit a good surface roughness for light scattering and low resistivities. ► A low resistivity of 2.18×10⁻⁴Ωcm and mobility of 46cm²V⁻¹s⁻¹ obtained for ZAO film annealed at 400°C.In the present study transparent conducting zinc aluminum oxide (ZAO) thin films were prepared by DC reactive magnetron sputtering technique. The films were deposited on glass substrates at 200°C and annealed from 200°C to 500°C. XRD patterns of ZAO films shows (002) diffraction peak of hexagonal wurtzite, meaning that the films have c-axis orientation perpendicular to the substrate. Crystallite size was calculated from X-ray diffraction (XRD) spectra using the Scherrer formula. The surface morphology of the films was observed by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The electrical conductivity increases with increase of annealing temperature. The activation energies of conduction were obtained from an Arrhenius equation. The best characteristics of ZAO films have been obtained for the films annealed at 400°C with an average transmittance of 88% and a minimum resistivity of 2.2×10⁻⁴Ωcm. The optical band gap, optical constants, and electron concentrations of ZAO films are obtained from UV–vis–IR spectrophotometer data.

Keywords: DC reactive magnetron sputtering; Annealing treatment; Structural properties; Electrical properties; Optical transmittance

Electrical anisotropy properties of ZnO nanorods analyzed by conductive atomic force microscopy by Yunfeng Wu; Naisen Yu; Dongping Liu; Yangyang He; Yuanda Liu; Hongwei Liang; Guotong Du (pp. 176-179).

► The electrical properties of one individual lying ZnO nanorod were performed by C-AFM measurement. ► Inhomogeneous spatial current distribution was detected. ► Current was detected along the side facets while no current was detected in the top plane for ZnO nanorod. ► The side facets were more conductive than the top facets of ZnO nanorods.In this study, we have prepared ZnO nanorods on cracked GaN substrates using aqueous solution method. Unique electrical characterization of one individual lying ZnO nanorod is analyzed by conductive atomic force microscopy (C-AFM). Effect of anisotropy properties on the conductivity of a single nanorod has been investigated. The current maps of ZnO nanorods have been simultaneously recorded with the topography which is gained by AFM-contact mode. The C-AFM measurement present local current–voltage ( I– V) characteristics of the side facets of one individual lying nanorod, however, no current is detected on the top facets of ZnO nanorods. Measurement results indicate that the side facets are more electrically active than the top facets of ZnO nanorods due to lower Schottky barrier height of the side facets.

Keywords: ZnO nanorods; Conductive atomic force microscopy; Schottky barrier height

Optical and structural characterization of pulsed laser deposited ruby thin films for temperature sensing application by Satchi Kumari; Alika Khare (pp. 180-186).

► Epitaxial ruby thin film is deposited on sapphire substrate. ► The PL spectra for R lines show highly crystalline stress free film with FWHM of 11.4cm⁻¹. ► PLD ruby thin film can be used as photonics based temperature sensor.The ruby thin films were deposited by pulsed laser deposition (PLD) technique in an atmosphere of oxygen using ruby pellet, indigenously prepared by mixing Al₂O₃ and Cr₂O₃ in appropriate proportion. The characteristics R₁ and R₂ lines at 694.2nm and 692.7nm in the photoluminescence spectra of target pellet as well as that of PLD thin films, confirmed the ruby phase in both. The XRD and Raman spectra confirmed deposition of c-axis oriented crystalline ruby thin film on sapphire substrate. Effect of deposition time, substrate and deposition temperature on PLD grown thin films of ruby are reported. The intensity of R₁ and R₂ lines of PLD ruby thin films increased enormously after annealing the film at 1000°C for 2h. The film deposited on sapphire substrate for 2h was 260nm thick and the corresponding deposition rate was 2.16nm/min. This film was subjected to temperature dependent photoluminescence studies. The peak positions of R₁ and R₂ lines and corresponding line width of PLD ruby thin film were observed to be blue shifted with decrease in temperature. R₁ line position sensitivity,dν¯/dT, cm⁻¹/K in the range 138–368K was very well fitted to linear fit and hence can be used as temperature sensor in this range.

Keywords: Thin film; Ruby (Al; ₂; O; ₃; :Cr; ³⁺; ); Temperature sensor

Constructing Ag nanoparticles–single wall carbon hybrid nanostructure to improve field emission properties by Leifeng Chen; Lei Wang; Xuegong Yu; Shijun Zhang; Dan Li; Chen Xu; Lingsheng Zeng; Shu Zhou; Jianjing Zhao; Fan Guo; Liqin Hu; Deren Yang (pp. 187-191).

► Ag nanoparticles–SWCNTs hybrid composites can be easily constructed using a wet chemical process. ► Constructing Ag–SWCNTs emitters could improve the electrical contact by increasing the contact area between SWCNTs and substrate. ► The field emission properties of SWCNTs including current density and emitting image were remarkably enhanced because of improvement of contact resistance.The overall process of field emission can be dominated by the contact resistance between the single wall carbon nanotubes (SWCNTs) and the substrate. In order to reduce the contact resistance, we present a wet chemical process of constructing Ag–SWCNTs hybrid nanostructure. Constructing Ag–SWCNTs emitters could improve the electrical contact by increasing the contact area between SWCNTs and substrate. Contact resistance is greatly reduced compared to that of pristine SWCNTs. Field emission properties of Ag–SWCNTs hybrid emitters including current density and emitting image are remarkably improved. Field emission properties based on the modified Fowler–Nordheim (F–N) equation are discussed. Our studies show that this method can enhance the field emission properties of the SWCNTs by improving the contact resistance and is a promising way for mass production of SWCNTs for field emission display.

Keywords: Single wall carbon nanotubes (SWCNTs); Field emission; Contact resistance; Ag nanoparticles; Hybrid nanostructure

Investigation of humidity-dependent nanotribology behaviors of Si(100)/SiO₂ pair moving from stick to slip by Jiaxin Yu; Lei Chen; Linmao Qian; Danlu Song; Yong Cai (pp. 192-200).

► The effect of humidity on the motion behavior of Si(100)/SiO₂ pair was clarified. ► With increase in humidity, adhesion force increases slowly firstly, then sharply. ► With increase in humidity, friction force increases sharply firstly, then slowly. ► The wear degree of Si is relative to the physical state of absorbed water film. ► The tribochemical reaction of Si(100) in humid air was verified by ToF-SIMS.With an atomic force microscopy, the humidity-dependent nanotribology behaviors of Si(100) against SiO₂ microsphere were investigated while the relative movement translated from stick to slip. The relative humidity RH of air exhibits a strong effect on the motion behavior of Si(100)/SiO₂ pair. With the increase in RH, relative movement of Si(100)/SiO₂ pair is easier to keep into stick state, namely, the relative slip becomes more difficult to occur in a higher humidity range. The adhesion F_a will increase with the increase in RH in the given humidity range. In the low RH range (<20%) where the adsorbed water layer forms the ‘solid-like’ structure, due to the absence of water meniscus, F_a increases very slowly. However, in relative higher RH range (>20%), F_a increases very sharply once ‘liquid-like’ adsorbed water layer forms, because it increases the capillary force. The initial friction forces F_t of Si(100)/SiO₂ pair also increase with the increase in RH in the given humidity range. However, different from F_a, it increases sharply in the low RH range (<30%) and slightly in the higher RH range (>30%). During the cyclic friction process, under the higher RH, relative stable tangential force is easier to be observed at higher displacement amplitude, here, the relative movement usually keeps into stick state. With the increase in RH, the surface damage of Si(100) transforms from mechanical deformation (forming hillock) to tribochemical wear (material removal). The tribochemical wear is sensitive to the absorbed water film with ‘solid-like’ structure, here, the wear volume increases drastically in this RH range (<20%); further increase of wear is small in higher relative humidity regime where the ‘liquid-like’ water layer is formed. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis verifies the water molecules participate into tribochemical reaction to rupture the SiSi and SiO network bonds on Si(100) substrate.

Keywords: Nanotribology; Nanowear; Humidity; Silicon

Imaging of Ti_0.87O₂ nanosheets using scanning tunneling spectroscopy by Avijit Kumar; Suresh Kumar C. Palanisamy; Jelmer M. Boter; Chris Hellenthal; Johan E. ten Elshof; Harold J.W. Zandvliet (pp. 201-204).

► Imaging of Ti_0.87O₂ nanosheets using scanning tunneling spectroscopy. ► di/dz map reveals Ti_0.87O₂ nanosheets rather than conventional topography scan. ► Lowering of effective barrier height Ti_0.87O₂ nanosheets on Pt(200nm)/Si surface.We report scanning tunneling microscopy (STM) and spectroscopy (STS) measurements on single layer Ti_0.87O₂ nanosheets deposited on Pt(200nm)/Si substrates. These nanosheets have a band gap of 3.8eV and are virtually invisible in conventional STM images. However, an impressive contrast is observed in the di/ dz map, which allows for a clear identification of the nanosheets. The di/ dz signal is obtained by adding a high frequency, small amplitude modulation to the z-piezo using a lock-in amplifier.

Keywords: Scanning tunneling microscopy; Scanning tunneling spectroscopy; Ti; _0.87; O; ₂; nanosheets

Electrochemical deposition and behavior of mixed-valent molybdenum oxide film at glassy carbon and ITO electrodes by Süleyman Koçak; Fatma Nil Ertaş; Zekerya Dursun (pp. 205-213).

Mixed-valent molybdenum oxide films have been deposited on GCE and ITO surfaces at different media by cyclic voltammetry. The deposited films were built upon cycling the potential between 0 and −0.9V via reduction of Mo(VI) to Mo(V) on this electrode surfaces in pH 3.0 solution. The catalytically effect of modified the surface was tested with nitrite oxidation in phosphate buffer pH 7.0. Surfaces of this electrode were characterized by using AFM, SEM, XPS, and QSM techniques.Display Omitted► The effect of solution composition on the MoO₃ formation was investigated. ► The mixed-valent oxide species was produced electrochemically on a GCE and ITO ► XPS studies confirmed that the deposit contains both Mo(V) and Mo(VI). ► The MoO₃ films were exhibited unique catalytic activity towards nitrite oxidation.The effect of solution composition and the type of the anionic species on the electrochemical formation of mixed-valent molybdenum oxide on a glassy carbon and ITO electrode surfaces was elucidated. Susccessive recording of the voltammograms has shown that anionic species display different stabilizing effect on the reductive formation of hydrogen molybdenum bronzes [MoO_3−x (OH)_x] and chloroacetic acid buffer has given the best results. The deposit was built upon cycling the potential between 0 and −0.9V (vs. Ag/AgCl) via reduction of Mo(VI) to Mo(V) on the electrode surface in pH 3.0 chloroacetic acid solution. Electrochemical impedance measurements carried out in this medium revealed a shift in potential zero charge values from -0.2V to -0.55V after the potential of the GCE had been cycled for 30min. An establishment of mixed-valent molybdenum oxide deposit by time on the gold electrode surface was proved by quartz crystal microbalance measurements. Atomic force and scanning electron microscopy techniques were made use of so as to characterize the surface structures of the electrodes. X-ray photoelectron spectroscopy studies confirmed that the deposit contains both Mo(V) and Mo(VI). The deposited films exhibited unique catalytic activity towards nitrite oxidation consistent with the change in peak characteristics.

Keywords: Mixed-valent molybdenum oxide; Cyclic voltammetry; Glassy carbon electrode; ITO; XPS

Fabrication and electrocatalytic application of functionalized nanoporous carbon material with different transition metal oxides by L. Samiee; F. Shoghi; A. Vinu (pp. 214-221).

Display Omitted► Fabrication of highly ordered functionalized nanoporous carbon material with different types of transition metal oxides. ► Novel electrocatalytic activity of functionalized nanoporous carbon material. ► Simultaneous effect of surface area and surface reactivity parameters on electrocatalytic activity.In the work presented here, an attempt is made to study the effect of functionalization with different transition metal oxides on the mesostructural properties as well as electrochemical behavior of Pt/nanoporous carbon supports.In this respect, the functionalized samples have been synthesized by using CMK-3 and metallocene as transition metal sources. The platinum catalysts (5wt% Pt) obtained through a conventional wet impregnation method. All the materials have been characterized by XRD (low and high), N₂ adsorption–desorption isotherms, high-resolution transmission electron microscopy, high-resolution field emission scanning electron, EDX mapping images and cyclic voltammetry (CV) and rotating disk electrode (RDE) techniques.The results showed that the mesostructural order has been destroyed by functionalization of CMK-3 with CoO, whereas it is not that much affected in NiO and CuO functionalized samples. EDX image mapping exhibited the good and uniform dispersion of functionalizing elements (Ni, Cu, Fe and Co), Pt in the carbon supports. Moreover, XRD studies revealed the formation of smaller platinum crystallite sizes in NiO and CuO functionalized samples in relative to other functionalized supports.Electrochemical measurements were performed using CV and RDE method. Kinetic analysis revealed an activity increases in the following order: CMK-3-NiO-Pt>CMK-3-CuO-Pt>CMK-3-CoO-Pt>CMK-3-Fe₂O₃-Pt which is showing of simultaneous effect of surface area and surface reactivity parameters.

Keywords: Rotating disk electrode; PEMFC; Nanoporous carbon; Functionalization; Transition metal oxides

Electrospray deposited Pt film for hydrogen evolution reaction: Effect of solvent solution by Jyotiprakash B. Yadav; Oh-Shim Joo (pp. 222-225).

► Electrospray technique is used for platinum film deposition from different solvent (water, ethanol and mixture of both). ► The effect of solvents of different physical properties on film properties is studied. ► Hydroxide form of Pt thin film is obtained from water solvent, with low activity for HER. ► Pure Pt film is obtained from ethanol solvent with high activity for HER. ► Mixed phase is obtained from mixture of both solvent and purity increased with ethanol.Pt film was prepared by electrospray deposition technique from solution prepared in different solvents (water, ethanol, and the mixture of both solvents), which was characterized by different analytical techniques. In the scanning electron microscopic images, the surface morphology of the film prepared from water solvent was porous, which was slowly changed into morphology of scattered spherical grains on highly compact and uniform surface with ethanol concentration. From the XPS spectra it was observed that the film prepared from water solvent was in hydroxide form, whereas the film prepared from ethanol was in pure Pt form. The film prepared from mixture of both the solvent was observed in mixed phases and its purity was found to be increased with ethanol concentration. The linear sweep plot was used for catalytic activity study of the film for hydrogen evolution reaction (HER) and PV assisted water electrolysis system for volumetric hydrogen production measurement. From the linear sweep plot low overpotential value concludes high catalytically active for HER, was observed in the film prepared from ethanol solvent, which (overpotential value) was found to increase in a film with increase in water solvent. The volumetric hydrogen evolution study also showed similar trend as observed in linear sweep plot.

Keywords: Thin film; Electrospray; XPS; Linear sweep; Hydrogen evolving electrode

Characterization of the plasma electrolytic oxidation of titanium in sodium metasilicate by S. Stojadinović; R. Vasilić; M. Petković; B. Kasalica; I. Belča; A. Žekić; Lj. Zeković (pp. 226-233).

► Plasma electrolytic oxidation (PEO) of titanium in sodium metasilicate. ► Spectroscopic study of the PEO process of titanium is conducted. ► Line shape analysis of hydrogen H_β line, two electron number densities detected.Plasma electrolytic oxidation (PEO) of titanium in sodium metasilicate at 200mA/cm² is investigated using real-time imaging and optical emission spectroscopy. It has been detected that during the PEO process the size of microdischarges becomes larger, while the number of microdischarges is reduced. The species and their ionization states present in PEO microdischarges are identified. The species originate both from titanium anode and from the electrolyte. The spectral line shape analysis of hydrogen Balmer line H_β (486.13nm) indicates the presence of two types of microdischarges during PEO. The discharges are characterized by relatively low electron number densities of N_e=3.8×10¹⁵cm⁻³ and N_e=4.5×10¹⁶cm⁻³. For electron temperature ( T_e) measurement we used Ti I lines at 398.18nm and 501.42nm and obtained T_e in the range of 3700±500K. Surface coatings formed by PEO process were characterized by AFM, SEM-EDX and XRD. The main elemental components of PEO coatings are Ti, Si and O. The PEO coatings are partly crystallized and mainly composed of anatase, rutile, and amorphous SiO₂.

Keywords: Titanium; Plasma electrolytic oxidation (PEO); Sodium metasilicate; Optical emission spectroscopy

Influence of electric field on laser damage properties of DLC films by unbalanced magnetron sputtering by Junqi Xu; Junhong Su; Lingxia Hang; Yaojin Cheng (pp. 234-238).

► Relationship between electric field and laser damage were studied. ► Laser damage properties of DLC films were investigated. ► The laser damage-resistance may be improved by optimizing the electric filed. ► Films with higher electric field are most likely first to be damaged. ► Lower electric filed intensity in DLC, smaller cracked spots.DLC films with different thicknesses were prepared on Si substrates by the unbalanced magnetron sputtering (UBMS) method using the same experimental parameters to investigate the relationship between electric field intensity distribution and laser damage properties of the samples. The results indicated that different electric field intensity distributions in the films cause diverse laser damage properties. For the DLC films with optical thicknesses of 287, 341, 421 and 545.9nm, the electric field intensity (normalized electric field intensity squared) at the film–air interface is 0.9407, 0.7709, 0.4298 and 0.2241 respectively when at the wavelength of 1064nm. Under the same high-energy laser irradiation, the size of cracked spots of the film with a lower electric filed intensity is smaller than that with higher electric field intensity. The laser-induced damage threshold (LIDT) of the DLC samples is 0.6, 0.8, 1.2 and 1.5J/cm² respectively (1064nm, 10ns). This shows that a higher LIDT may be obtained provided the films have lower electric field intensity at the film–air interface. Therefore, the laser damage-resistance ability of the films can be improved by optimizing the electric field to one with lower intensity during the process of film stack design and materials matching.

Keywords: Diamond-like carbon films; Unbalanced magnetron sputtering (UBMS); Electric field intensity; Laser-induced damage threshold (LIDT)

An innovative method for joining materials at low temperature using silver (nano)particles derived from [AgO₂C(CH₂OCH₂)₃H] by Annerose Oestreicher; Tobias Röhrich; Johannes Wilden; Martin Lerch; Alexander Jakob; Heinrich Lang (pp. 239-244).

Display Omitted► We achieved pressureless copper-to-copper silver joints at low temperatures. ► Enrichment of the silver layer with copper was possible. ► Formation of a molten metal-like silver phase was beneficial for joining. ► We report on the phase stages of different silver carboxylates. ► Formation of nanoparticles allows low temperature sintering.A novel method for the manufacture of compact sintered silver layers as joining materials at low temperatures without applying pressure is described. The metal–organic silver complex [AgO₂C(CH₂OCH₂)₃H] (3) is used, which generates silver nanoparticles with heat treatment below 200°C. Complex (3) provides the features for the formation of a molten metal-like silver phase in which silver particles in the nanometer and submicron size range, respectively, are completely miscible. Within this study, copper specimens were bonded, and the joints were evaluated by cross-sectional scanning electron microscope (SEM) images. Moreover, this approach enables the incorporation of copper. An example is given with an average amount of 20at.% copper content in the silver layer.

Keywords: Metal–organic silver complex; Silver nanoparticles; Pressureless sintering; Low temperature; Copper-to-copper silver joints

Deposition of titanium nitride layers by electric arc – Reactive plasma spraying method by Viorel-Aurel Şerban; Radu Alexandru Roşu; Alexandra Ioana Bucur; Doru Romulus Pascu (pp. 245-249).

► Titanium nitride layers deposited by electric arc – reactive plasma spraying method. ► Deposition of titanium nitride layers on C45 steel at different spraying distances. ► Characterization of the coatings hardness as function of the spraying distances. ► Determination of the corrosion behavior of titanium nitride layers obtained.Titanium nitride (TiN) is a ceramic material which possesses high mechanical properties, being often used in order to cover cutting tools, thus increasing their lifetime, and also for covering components which are working in corrosive environments.The paper presents the experimental results on deposition of titanium nitride coatings by a new combined method (reactive plasma spraying and electric arc thermal spraying). In this way the advantages of each method in part are combined, obtaining improved quality coatings in the same time achieving high productivity. Commercially pure titanium wire and C45 steel as substrate were used for experiments.X-ray diffraction analysis shows that the deposited coatings are composed of titanium nitride (TiN, Ti₂N) and small amounts of Ti₃O. The microstructure of the deposited layers, investigated both by optical and scanning electron microscopy, shows that the coatings are dense, compact, without cracks and with low porosity. Vickers microhardness of the coatings presents maximum values of 912 HV0.1. The corrosion tests in 3%NaCl solution show that the deposited layers have a high corrosion resistance compared to unalloyed steel substrate.

Keywords: Titanium nitride; Reactive plasma spraying; Electric arc thermal spraying

Dense and porous titanium substrates with a biomimetic calcium phosphate coating by A.A. Ribeiro; R.M. Balestra; M.N. Rocha; S.B. Peripolli; M.C. Andrade; L.C. Pereira; M.V. Oliveira (pp. 250-256).

► A biomimetic coating method with simplified solution is proposed. ► Titanium substrates are submitted to chemical and heat treatments. ► Titanium substrates are coated with biocompatible calcium phosphate phases. ► The simplified solution shows potential to be applied as a coating technique.The present work studied a biomimetic method using a simplified solution (SS) with calcium and phosphorus ions for coating titanium substrates, in order to improve their bioactivity. Commercially pure titanium dense sheet, microporous and macroporous titanium samples, both produced by powder metallurgy, were treated in NaOH solution followed by heat-treating and immersed in SS for 7, 14 or 21 days. The samples characterization was performed by quantitative metallographic analysis, confocal scanning optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and low angle X-ray diffraction. The results showed coatings with calcium phosphate precipitation in all samples, with globular or plate-like morphology, typical of hydroxyapatite and octacalcium phosphate, respectively, indicating that the solution (SS) has potential for coating titanium substrates. In addition, the different surfaces of substrates had an effect on the formed calcium phosphate phase and thickness of coatings, depending on the substrate type and imersion time in the simplified solution.

Keywords: Calcium phosphate; Coating; Titanium; Biomimetic

Synthesis of Al₂O₃ thin films using laser assisted spray pyrolysis (LASP) by Baban P. Dhonge; Tom Mathews; S. Tripura Sundari; R. Krishnan; A.K. Balamurugan; M. Kamruddin; R.V. Subbarao; S. Dash; A.K. Tyagi (pp. 257-263).

► Alumina thin films were made by laser assisted spray pyrolysis at various laser powers. ► The particle size was found to increase with laser power. ► The refractive index of the films was studied using ellipsometry. ► The film stoichiometry was studied using X-ray photoelectron spectroscopy. ► The film/substrate interface was studied using ellipsometer and secondary ion mass spectrometer.The present study reports the development of a laser assisted ultrasonic spray pyrolysis technique and synthesis of dense optical alumina films using the same. In this technique ultrasonically generated aerosols of aluminum acetylacetonate dissolved in ethanol and a laser beam (Nd:YAG, CW, 1064nm) were fed coaxially and concurrently through a quartz tube on to a hot substrate mounted on an X– Y raster stage. At the laser focused spot the precursor underwent solvent evaporation and solute sublimation followed by precursor vapor decomposition giving rise to oxide coating, the substrate is rastered to get large surface area coating. The surface morphology revealed coalescence of particles with increase in laser power. The observed particle sizes were 17nm for films synthesized without laser and 18, 21 and 25nm for films made with laser at 25, 38 and 50W, respectively. Refractive index of the films synthesized increased from 1.56 to 1.62 as the laser power increased from 0 to 50W. The stoichiometry of films was studied using XPS and the increase in interfacial layer thickness with laser power was observed from dynamic SIMS depth profiling and ellipsometry.

Keywords: Laser assisted spray pyrolysis; Ellipsometry; Amorphous Al; ₂; O; ₃; thin films; Secondary ion mass spectrometry

Investigation of the bond coats for thermal barrier coatings on Mg alloy by Xizhi Fan; Binglin Zou; Lijian Gu; Chunjie Wang; Ying Wang; Wenzhi Huang; Ling Zhu; Xueqiang Cao (pp. 264-273).

► Bond coats of Al@Ni, MCrAlY(M=Co, Ni) and Ni@Al for Mg alloy were investigated. ► The bond coats had moderate TECs (13–15×10⁻⁶K⁻¹). ► The structure of original powders affected the properties of the sprayed bond coats. ► MCrAlY bond coat had excellent oxidation resistance at 400–500°C. ► MCrAlY bond coat had excellent corrosion resistance in 3.5% NaCl solution. ► MCrAlY was demonstrated as the most appropriate bond coat for TBCs on Mg alloy.Bond coats play a significant role in manipulating the stability of 8YSZ thermal barrier coatings (TBCs) deposited on Mg alloy. In this study, different bond coats from the Al@Ni, Ni@Al and MCrAlY (M=Co, Ni) powders were prepared on the Mg alloy by atmospheric plasma spraying. The spraying behavior of the powders, the microstructure, oxidation and corrosion resistance of the produced bond coats were investigated to find the positive bond coat for TBCs on Mg alloy. Results indicate that the composition and structure of original powders affect the structure and properties of the sprayed bond coats. For the candidate bond coats, the MCrAlY bond coat is demonstrated as the most appropriate one for 8YSZ TBCs deposited on Mg alloy substrate, which is mainly attributed to its moderate thermal expansion match and excellent corrosion and oxidation resistance under the simulated corrosion and relatively high temperature conditions.

Keywords: Bond coat; Oxidation; Corrosion; Stability; Mg alloy; Plasma spraying

Investigation on NOx adsorption in [M′]-MAPO-5 (M=Si, Ti; M′=Ag, Cu) by density functional theory calculation by Jiexiang Liu; Xiaoguang Zhang (pp. 274-280).

► [M′]-MAPO-5 (M=Si, Ti; M′=Ag, Cu) has good resistance capability to H₂O and SO₂. ► Adsorption strength follows the decreasing order of NO₂>NO>N₂O. ► [Cu]-MAPO-5 is more effective for the activation of NO_x than [Ag]-MAPO-5. ► [M′]-MAPO-5 has a stronger adsorption for NO, NO₂, SO₂and O₂ than [M′]-AlMOR. ► NBO results are in reasonable agreement with adsorption interaction strengths.NO, N₂O and NO₂ adsorption in [M′]-MAPO-5 (M=Si, Ti; M′=Ag, Cu) models of the modified aluminophosphate molecular sieves was investigated by density functional theory (DFT) method. The equilibrium structural parameters and adsorption energies were obtained and compared. The structural parameters of NO and NO₂ in the adsorbed state had a distinct change than that of N₂O compared to their free gas state. [M′]-MAPO-5 was more effective for the activation of NO_x molecule compared to [M′]-AlMOR (M′=Ag, Cu) models of the modified mordenite in our previous studies. The adsorption energies data indicated that adsorption strength of NO_x followed the decreasing order of NO₂>NO>N₂O. And adsorption complexes in η¹-N mode were much stabler than that in η¹-O mode, which was similar to that in [M′]-AlMOR. [Cu]-MAPO-5 had a much stronger adsorption for NO_x than [Ag]-MAPO-5. And [M′]-SiMOR had a little stronger adsorption for NO_x than [M′]-TiMOR. Furthermore, the resistance capabilities of [M′]-MAPO-5 to SO₂, H₂O and O₂ were studied and analyzed. The interaction mechanism of NO_x adsorption in [M′]-MAPO-5 was also discussed by natural bond orbital (NBO) analysis, which was in reasonable agreement with the adsorption interaction strengths.

Keywords: Nitrogen oxide; Aluminophosphate molecular sieve; Copper; Silver; Adsorption; Density functional theory (DFT)

Surface characterization and assessment of cell attachment capabilities of thin films fabricated by ion-beam irradiation of poly(l-lactic acid) substrates by Toshiyuki Tanaka; Yoshiaki Suzuki; Koji Tsuchiya; Hirofumi Yajima (pp. 281-285).

► Thin films can be obtained by ion-beam irradiation of poly(l-lactic acid). ► Both surfaces of the thin film were carbonized by the irradiation. ► No significant changes were noticed in the topographies of the two surfaces. ► Fibroblasts attached firmly to the bottom as well as the top surface of the film.The ion-beam irradiation of substrates of poly(l-lactic acid) (PLLA), a biodegradable polymer, gave rise to exfoliatable thin films when the substrate was immersed in an aqueous solution. The thin films exhibited excellent cell affinity, and hence, can be useful in bioengineering applications. In this study, we characterized both surfaces of the thin films and evaluated their cell attachment capabilities. Each surface was analyzed by X-ray photoelectron spectroscopy (XPS) and dynamic force microscopy (DFM). These analyses showed that carbonization took place at both surfaces. In addition, no significant changes were noticed in the topographies of the two surfaces. Finally, the cell attachment capabilities of the surfaces were determined by culturing mouse fibroblasts on them. The cells attached firmly to the bottom as well as the top surface of the film and were well spread out. These results could be attributed to the carbonization of the surfaces of the thin-film. Such thin films, fabricated by the irradiation of a biodegradable polymer, are expected to find wide application in areas such as tissue regeneration and cell transplantation.

Keywords: Ion-beam irradiation; Poly(; l; -lactic acid); Thin film; Cell attachment; Surface characterization

Thermodynamics of the formation of face-centered-cubic silicon nanocrystals in silicon-rich SiC thin films annealed using rapid thermal annealing by Yuheng Zeng; Xiaobo Chen; Qiang Cheng; Junhua Zhao; Weijie Song; Ning Dai (pp. 286-290).

► Fcc-structured Si-NCs were formed in the surface layer of SiC-matrix thin film. ► Nucleation of fcc-structured Si-NCs was demonstrated using thermodynamics. ► Gibbs free energy and surface energy determined the structure of Si-NC nuclei. ► Nano-induced pressure was helpful for the nucleation of fcc-structured Si-NCs. ► Formation of fcc-structured Si-NCs was unrelated to the effect of carbon-doping.Silicon nanocrystals (Si-NCs) in silicon carbide (SiC) matrix fabricated by rapid thermal annealing were characterized using grazing incidence X-ray diffraction and transmission electron microscopy. Two structures of Si-NCs were found in the thin films. Si-NCs in the surface layer had face-centered cubic ( fcc) structure, whereas those in the inner layer had cubic diamond ( cd) structure. The thermodynamics for the formation of fcc-structured Si-NCs was demonstrated. We suggested that two main factors, Gibbs free energy per atom and surface energy, determined what structure of Si-NC nucleus to be formed. Specifically, reducing the Gibbs free energy per atom of fcc-Si crystal and lowering the surface energy of fcc-Si crystal would be helpful for the formation of fcc-structured Si-NC nucleus. In addition, the effects of carbon and substrate on the formation of Si-NCs were discussed. The work suggested that fcc-structured Si-NCs were readily generated in the surface layer of Si-rich SiC thin films.

Keywords: Silicon nanocrystal; Face-centered cubic; Thermodynamics; SiC matrix

Growth and structure of Si and Ge in vanadium oxide nanomesh on Pd(111) studied by STM and DFT by Lap Hong Chan; Shinji Hayazaki; Kokushi Ogawa; Junji Yuhara (pp. 291-295).

Display Omitted► We studied the growth and structure of Si and Ge in vanadium oxide nanomesh on Pd(111) by STM and DFT calculations. ► All the Si atoms formed isolated Si nanoclusters. ► Some Ge atoms formed monomer Ge nanodots on Pd(111), while the others formed isolated Ge nanoclusters.The growth of silicon (Si)/germanium (Ge) atoms in a well ordered (4×4) vanadium (V) oxide nanomesh on Pd(111) prepared by ultra-high-vacuum evaporation has been studied by scanning tunneling microscopy (STM) and ab initio density functional theory (DFT) calculations. At the very beginning of the Si deposition, all of the Si atoms deposited were adsorbed on top of the V-oxide nanomesh, forming Si nanoclusters, and each Si atom formed was isolated other Si atoms. Two different adsorption sites for Si atoms were observed by STM. In the case of Ge deposition, some Ge atoms filled the vanadium oxide nanoholes, forming Ge nanodots on Pd(111), while the others were adsorbed on top of the V-oxide nanomesh, forming isolated Ge nanoclusters. The ab initio DFT total-energy calculations indicated that the Ge atoms occupying the nanohole were more stable than those adsorbed on the nanomesh. The simulated images were highly consistent with the experimental STM images with the exception of the Ge nanodots, which exhibited a large, uniform protrusion in the STM images. Therefore, the adsorbed atom might be mobile in the nanohole at room temperature, possibly as a result of interaction with the STM tip.

Keywords: Nanodot; Nanocluster; Nanomesh; Silicon; Germanium; Vanadium oxide; Palladium; Scanning tunneling microscopy; DFT calculations

Effect of SHI irradiation on NBT–BT ceramics: Transformation of relaxor ferroelectric to ferroelectric nature by S. Shanmuga Sundari; Binay Kumar; K. Asokan; R. Dhanasekaran (pp. 296-301).

► The NBT–BT ceramics at MPB were synthesized by conventional solid state reaction method. ► The prepared ceramics were irradiated with 120MeV Au⁹⁺ ions at different fluencies. ► The grain size is increased after irradiation due to the increase of local lattice temperature. ► As the fluence increases the relaxor nature of the material is transformed to the ferroelectric nature.The lead free NBT–BT ceramics prepared by conventional solid state reaction method were irradiated with 120MeV Au⁹⁺ ions with different fluences. The structural, dielectric and piezoelectric studies were carried out before and after irradiation. The agglomeration and increase of grain size are observed in SEM analysis after the irradiation. The diffuse phase transition disappeared after high fluence of irradiation and the material becomes ferroelectric in nature. The piezoelectric properties were decreased due to the reduced stability of the ferroelectric domains after the irradiation.

Keywords: Lead free; Relaxor ferroelectrics; Swift heavy ion irradiation; NBT–BT

Micromachining of copper by femtosecond laser pulses by S.Y. Wang; Y. Ren; C.W. Cheng; J.K. Chen; D.Y. Tzou (pp. 302-308).

► We have reported new experimental and theoretical results on the femtosecond laser ablation for copper at fluences up to 408J/cm². ► The present model simulations correlate well with the experimental data over a broad range of laser fluences from 0.8 to 400J/cm². ► The good correlation suggests that the proposed model is an efficient and accurate tool for predicting ultrafast laser material ablation.Simulation results of femtosecond laser ablation of copper were compared to experimental data. The numerical analysis was performed using a predictive model, including a two temperature model, an optical critical point model with three Lorentzian terms, two phase change models for melting and evaporation under superheating, and a phase explosion criterion for ejection of metastable liquid decomposing into droplets and vapor phase. The experiments were conducted with a 120-fs, 800-nm Ti:sapphire lasers for fluences up to 408J/cm². The ablation depths were measured, and the ablation rate was estimated. It was shown that the present numerical simulations correlate well with the experimental data over the entire range of the laser fluences investigated except for those below 0.8J/cm², indicating that the proposed model is an accurate and efficient tool for predicting ultrashort-pulsed laser material ablation.

Keywords: Femtosecond laser; Material ablation; Two-temperature model; Superheating; Phase explosion

TiO₂ nanotubes supported NiW hydrodesulphurization catalysts: Characterization and activity by R. Palcheva; L. Dimitrov; G. Tyuliev; A. Spojakina; K. Jiratova (pp. 309-316).

Display Omitted► NiW catalysts supported on TiO₂ nanotubes, titania and alumina. ► The best results are obtained with NiW/TiO₂ nanotubes in hydrodesulfurization (HDS) of thiophene. ► Active phase is Ni-WO_xS_y. ► Electronic promotion of W by Ti.High surface area TiO₂ nanotubes (Ti-NT) synthesized by alkali hydrothermal method were used as a support for NiW hydrodesulphurization catalyst. Nickel salt of 12-tungstophosphoric acid – Ni_3/2PW₁₂O₄₀ was applied as oxide precursor of the active components. The catalyst was characterized by S_BET, XRD, UV–vis DRS, Raman spectroscopy, XPS, TPR and HRTEM. The results obtained were compared with those for the NiW catalysts prepared over high surface area titania and alumina supports. A polytungstate phase evidenced by Raman spectroscopy was observed indicating the destruction of the initial heteropolyanion. The catalytic experiments revealed two times higher thiophene conversion on NiW catalyst supported on Ti-NT than those of catalysts supported on alumina and titania. Increased HDS activity of the NiW catalyst supported on Ti-NT could be related to a higher amount of W oxysulfide entities interacting with Ni sulfide particles as consequence of the electronic effects of the Ti-NT observed with XPS analysis.

Keywords: Nano-structured TiO; ₂; NiW catalysts; Thiophene hydrodesulphurization; XPS

Production of stable hydrosols of crystalline TiO₂ nanoparticles synthesized at relatively low temperatures in diverse media by Esin Burunkaya; Murat Akarsu; H. Erdem Çamurlu; Ömer Kesmez; Zerin Yeşil; Meltem Asiltürk; Ertuğrul Arpaç (pp. 317-323).

Display Omitted► Crystalline, nanosize TiO₂ particles were synthesized under reflux without calcination. ► Surface of nanoparticles were modified in situ with alkoxy groups of the solvent used. ► In situ surface-modified nanoparticles dispersed in both polar and non-polar media. ► Optically transparent TiO₂ hydrosols were prepared. ► They have photocatalytically degraded Rhodamine B.TiO₂ hydrosols were obtained by dispersing nanoparticles synthesized from titanium ethoxide as precursor via reflux method without any further thermal treatment. In this study, the reaction parameters such as solvent, type of catalyst, temperature and duration of the synthesis of TiO₂ nanoparticles were extensively investigated. The crystalline nanoparticles obtained without calcination have particle size in range of 3.3nm and 5nm, and BET surface area of up to 182m²/g. Transparent TiO₂ hydrosols were prepared in both water and non-polar solvent without use of any additional dispersing agent. The synthesized nanoparticles exhibited photocatalytic activity against Rhodamine B dye.

Keywords: TiO; ₂; Hydrosol; Nanoparticle; Photocatalysis; Reflux synthesis; Rhodamine B

Optical properties of nanocrystal-silicon thin films on silicon nanopillar arrays after thermal annealing by Yonglei Li; Bo Qian; Cong Li; Jun Xu; Chunping Jiang (pp. 324-328).

► A combined structure with nc-Si film and silicon nanopillar array is demonstrated. ► The reflectance spectra of this structure have revealed a remarkable reduction. ► The structure shows a wide-range tunability of light emission efficiency.The optical properties of nanocrystal-silicon (nc-Si) thin films on silicon nanopillar arrays after thermal annealing treatments have been investigated in this paper. The structure was prepared by SiO₂ nanosphere lithography, reactive-ion etching, conformal deposition method and thermal annealing treatment, successively. The thickness of nc-Si thin film is about 100nm, while the diameter, period and height of silicon nanopillar arrays are about 250nm, 500nm and 1μm, respectively. By reflectance and photoluminescence (PL) spectroscopy measurements in visible to near-infrared wavelength range, a minimum reflectivity of about 0.7% has been demonstrated in such a kind of structure, meanwhile, a large variation (from 12.5 times of suppression to 8.8 times of enhancement compared to the flat referential thin films) of the light emission efficiencies of the samples depending on the thermal annealing temperatures has been observed, which is due to the temperature dependent modification of optical constants of nc-Si thin films. By combining the nc-Si with silicon nanopillar array, the structure will be very promising for the design of radial p–i–n junction solar cell devices.

Keywords: Nanocrystal-silicon; Nanopillar array; Reflectivity; Photoluminescence; Solar cell

Formation of α-TeO₂ pearl-like microwires templated on porous microtubes through thermal oxidation of Te microtubes by E. Filippo; T. Siciliano; A. Genga; G. Micocci; M. Siciliano; M. Tepore (pp. 329-333).

Display Omitted► Te microtubes were thermally oxidized in a tube furnace at different temperatures. ► Novel α-TeO₂ microstructures were obtained. ► They consisted of porous scaffold microtubes covered with pearl-like microwires. ► The possible formation mechanism of the obtained microstructures was discussed.The current work demonstrates the first reported successful synthesis of unique α-TeO₂ hybrid microstructures through thermal oxidation of Te microtubes in a horizontal tube furnace at different temperatures in the range 220–470°C, under oxygen flow. The obtained microstructures were carefully characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectroscopy. They exhibited characteristic morphologies with porous scaffold microtubes covered along their whole length with pearl-like microwires. The possible formation mechanism of the obtained microstructures was also discussed.

Keywords: Oxidation; Tellurium oxide; Microtube; Microwire

Composition–phase structure relationship and thickness-dependent ferroelectricity of rhombohedral phase in [111]-textured Nb-doped Pb(Zr,Ti)O₃ thin films by Qi Yu; Jing-Feng Li; Wei Sun (pp. 334-338).

► We fabricated highly [111]-textured Nb-doped PZT thin films on silicon substrates by sol–gel approach. ► The orientation degree, film morphology and phase transition of the Nb-doped PZT films were investigated as a function of Zr/Ti ratios. ► We detected the thickness-dependent ferroelectricity of rhombohedrel composition thin films. ► The origin of the thickness-dependent ferroelectricity in [111]-oriented system was discussed.2% Nb-doped [111]-oriented lead zirconate titanate films (PNZT) of different Zr/Ti ratios ranging from 30/70 to 70/30 with a fixed thickness were deposited on the Pt(111)/Ti/SiO₂/Si(100) substrates by sol–gel method. The orientation degree, film morphology and phase transition of the PNZT films were investigated as a function of Zr/Ti ratios. The experimental results verified the composition-dependent phase transition from tetragonal to rhombohedral of the PNZT films with a visible [111] preferred orientation. To obtain high performance by making use of rhombohedrel [111]-oriented thin films, Pb(Zr_0.6Ti_0.4)Nb_0.02O₃ films with various thicknesses varying from 70nm to 300nm were studied to reveal the relationship among the film thickness, stress and ferroelectric response. It was found that ferroelectric property reached a high remnant polarization ( P_r) of 61.7μC/cm² and a minimum coercive field ( E_c) of 70.7kV/cm at 300nm due to the release of residual tensile stress.

Keywords: PZT thin films; Texture; Ferroelectricity; Thickness-dependence

First-principles based phenomenological study of Ni nanocubes: The effects of nanostructuring on carbon poisoning of Ni(001) nanofacets by Renbo Zhao; Seung Jae Lee; In Hyuk Son; Hyunjoo Lee; Aloysius Soon (pp. 339-345).

Ultra-small Ni nanocubes (perhaps 5nm in size or smaller) as nanocatalysts for the reforming reactions of methane are studied and proposed as a possible alternative to alleviate the problem of carbon poisoning in reforming technologies.Display Omitted► Binding energies of carbon and surface carbidic structures on Ni(001)-facets. ► Phenomenological model to mimic nanostructuring effects on carbon binding. ► Ultra-small Ni nanocubes as nanocatalysts could relief carbon poisoning.Ni-based catalysts are long known to be an efficient low-cost catalyst for the dry (or steam) reforming of methane. However, they are often plagued with the serious issue of carbon poisoning, eventually leading to the deactivation of Ni-based catalysts for this reaction. In order to provide an atomistic, electronic structure-based examination of Ni-based catalyst deactivation, we perform first-principles density-functional theory (DFT) calculations of chemisorbed carbon and other surface carbidic structures on Ni(001). This surface is the predominant surface of the nanocube catalysts engineered via shape-control synthesis for steam/dry reforming of methane. We calculate the chemical binding energy of carbon as a function of its surface coverage and we study the local chemical environment via its electronic structure to draw correlations between the thermodynamic (de)stability of these unwanted carbidic structures. In an attempt to mimic bond contraction at the surface of nanocatalysts, we report the influence of surface stress on our calculated values using a shape-dependent phenomenological bond contraction model.

Keywords: Density-functional theory; Carbon coking; Nickel nanocubes

Ag nanoparticles as multifunctional SERS substrate for the adsorption, degradation and detection of dye molecules by Yongmei Ma; Qianqian Ding; Liangbao Yang; Li Zhang; Yuhua Shen (pp. 346-351).

Display Omitted► A simple method was used to synthesize the silver Ag NPs. ► Change the reaction condition to obtain the best plasmon peak of Ag NPs. ► The multifunction of Ag NPs was analyzed for using as SERS substrate, adsorbent, and photocatalyst. ► Endows a new value of the SERS technique of monitoring the photocatalytic processes.Ag NPs were obtained by isopropyl alcohol restore silver nitrate with silicotungstic acid as a stabilizer under the condition of UV irradiation. From changing the amount of isopropyl alcohol and silver nitrate, we obtained Ag NPs of which plasmon peak was similar to the excitation wavelength, and the enhancement effect will be greatly improved. Enriching, degrading, and detecting dye molecular can be achieved by the simple SERS substrate, and the photo-degradation process was monitored by SERS successfully for the first time, and the sensitivity was improved compare to traditional detection by UV–vis spectroscopy.

Keywords: Multifunctional; Dye molecules; Detection; New application

Fabrication of novel micro–nano carbonous composites based on self-made hollow activated carbon fibers by Yuxia Kong; Tingting Qiu; Jun Qiu (pp. 352-357).

Display Omitted► Hollow pipe and porous HACF with solid carbon net framework structure were successfully prepared by template method. ► CNTs were grown successfully on the self-made HACF substrate by CVD techniques. ► A novel tree-like micro-nano carbonous structure CNTs/HACF was fabricated. ► The formation mechanism of micro phase HACF and nano phase CNTs were respectively discussed.The hollow activated carbon fibers (HACF) were prepared by using commercial polypropylene hollow fiber (PPHF) as the template, and phenol-formaldehyde resin (PF) as carbon precursors. Final HACF was formed through the thermal decomposition and carbonization of PF at 700°C under the nitrogen atmosphere, and activation at 800°C with carbon dioxide as the activating agent, consecutively. Then, carbon nanotubes (CNTs) were grown by chemical vapor deposition (CVD) techniques using the as-grown porous HACF as substrate. The growth process was achieved by pyrolyzing ethanol steam at 700°C using nickel as catalyst. Finally, CNTs was grown successfully on the substrate, and a novel tree-like micro–nano carbonous structure CNTs/HACF was fabricated. The as-grown HACF and micro–nano CNTs/HACF were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TG), respectively. Moreover, the formation mechanisms were also discussed.

Keywords: Template method; Hollow carbon fibers; Chemical vapor deposition; Carbon nanotubes; Micro–nano carbonous composites

Quantification of strain through linear dichroism in the Si 1s edge X-ray absorption spectra of strained Si1−_xGe_x thin films by W. Cao; M. Masnadi; S. Eger; M. Martinson; Q.-F. Xiao; Y.-F. Hu; J.-M. Baribeau; J.C. Woicik; A.P. Hitchcock; S.G. Urquhart (pp. 358-362).

Display Omitted► Silicon 1s X-ray absorption spectra (XAS) are sensitive to strain in SiGe alloys. ► Strain sensitivity arises from XAS linear dichroism differences. ► We demonstrate a quantitative relationship between strain and spectra.We have quantitatively measured the angle dependence in the Silicon 1s X-ray absorption spectra of strained Si1−_xGe_x thin films prepared by epitaxial growth on Si(100) substrates, through surface sensitive total electron yield detection. The linear dichroism difference extracted from these angle dependent X-ray absorption spectra is proportional to the degree of strain, as measured separately by Raman spectroscopy. This quantitative relationship provides a means to measure the compressive strain in Si1−_xGe_x thin films. This strain-dependent X-ray absorption spectroscopy has the potential to realize a semiconductor strain metrology through high spatial resolution X-ray spectromicroscopy.

Keywords: Strain; Silicon germanium alloys; X-ray absorption spectroscopy; NEXAFS

Mechanism for wettability alteration of ZnO nanorod arrays via thermal annealing in vacuum and air by Jun Zhang; Yanru Liu; Zhiyang Wei; Junyan Zhang (pp. 363-368).

► Oxygen vacancy is the key factor in accounting for the change in morphology of the ZnO nanorod arrays. ► We firstly investigated the wettability alteration of ZnO nanorod arrays annealed in vacuum at different temperature. ► The hydrophilicity of the ZnO nanorod arrays annealed in air is not related to the oxygen vacancy but ascribed to the O adatom on the nanorod surface.The ZnO nanorod arrays were synthesized via a simple hydrothermal process followed by annealing in vacuum and air respectively at different temperature. The wettability of samples was controlled by adjusting the annealing atmosphere and temperature. To investigate the mechanism of wettability alteration, the chemical composition and surface morphology of nanorod arrays were analyzed by X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FE-SEM), respectively. Increasing oxygen vacancy concentration by increasing annealing temperature in vacuum resulted in a great change of surface morphology, which played the major role in wettability change. Under annealing in air, oxygen vacancy concentration reduced and the surface morphology of nanorod arrays showed little change with increasing annealing temperature. The wettability alteration is ascribed to the O adatom on the nanorods surface.

Keywords: ZnO nanorod arrays; Wettability; Annealing; Oxygen vacancy

Characterization of electrodeposited Ni–SiC–C_g nanocomposite coating by Mohsen Rostami; Abbas Fahami; Bahman Nasiri-Tabrizi; Reza Ebrahimi-Kahrizsangi; Ahmad Saatchi (pp. 369-374).

Display Omitted► Ni–SiC–C_g nanocomposite coating was deposited onto the St-37 substrate by electrodeposition method. ► From XRD, all of the coatings show high crystallinity degree. ► All the samples had a typical cluster like structures with the average crystallites size of 60nm. ► Mechanical properties were improved with increasing of pH values up to 4.8 (593 HV). ► At pH equal to 4.8, Ni–SiC–C_g nanocomposite coating with suitable characteristics has been obtained.Nickel–silicon carbide–graphite (Ni–SiC–C_g) nanocomposite coating was deposited onto the steel (St-37) substrate by electrochemical plating method. The influence of pH parameter on the mechanical properties and morphological features was studied. The coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Elemental mapping analysis system, and field emission scanning electron microscopy (FE-SEM) techniques. Besides, the microhardness of specimens was measured by Micro hardness Tester. Based on XRD results, the dominant phases with high crystallinity degree were nickel, silicon carbide and graphite. Microscopic observations illustrated that all the coatings had a cluster like structures which consisted of some fine sphere particles with an average crystallites size of 60nm. Among of all coatings, the specimen at pH equal to 4.8 presented an appropriate morphology as well as lower porosity with high grain boundaries. Moreover, elemental mapping spectra exhibited a homogenous distribution of nickel, silicon and carbon particles. However, the distribution of silicon particles into nickel matrix at pH=4.8 was higher than the other samples. Also, mechanical properties of the attained coatings were improved with increasing of pH values up to 4.8 (593 HV) which is in agreement with microstructural characteristics. Therefore, obtaining of the optimum pH value is the major parameter in electroplating of Ni based nanocomposite which affected microhardness and distribution of reinforcement particles into the matrix.

Keywords: Electrochemical plating; Ni–SiC–C; _g; nanocomposite; pH value; Morphological features; Microhardness

The calculation of surface free energy based on embedded atom method for solid nickel by Wenhua Luo; Wangyu Hu; Kalin Su; Fusheng Liu (pp. 375-378).

► A new solution for accurate prediction of surface free energy based on embedded atom method was proposed. ► The temperature dependent anisotropic surface energy of solid nickel was obtained. ► In isotropic environment, the approach does not change most predictions of bulk material properties.Accurate prediction of surface free energy of crystalline metals is a challenging task. The theory calculations based on embedded atom method potentials often underestimate surface free energy of metals. With an analytical charge density correction to the argument of the embedding energy of embedded atom method, an approach to improve the prediction for surface free energy is presented. This approach is applied to calculate the temperature dependent anisotropic surface energy of bulk nickel and surface energies of nickel nanoparticles, and the obtained results are in good agreement with available experimental data.

Keywords: Surfaces free energy; Nanoparticles; Thermal properties; Embedded atom method

Co₃O₄/ZnO nanocomposites for gas-sensing applications by Yuanjun Liu; Guoxing Zhu; Junzhi Chen; Huan Xu; Xiaoping Shen; Aihua Yuan (pp. 379-384).

Display Omitted► By a facile wet-chemistry route Co₃O₄/ZnO nanocomposites were successfully prepared. ► The ZnO is loaded on the surface of Co₃O₄ nanoparticles with compact hetero-interface. ► The obtained nanocomposites exhibit enhanced gas sensing properties with good stability and high sensing response. ► The excellent gas sensing properties and the easily scaled-up preparation route make the prepared nanocomposites promising for real application.Co₃O₄/ZnO nanocomposites were prepared by an easy wet-chemistry route without any organic additive or surfactant used. The nanocomposites were systematically characterized by X-ray powder diffraction, scanning electron microscopy, (high-resolution) transmission electron microscopy, selected area electron diffraction, and energy-dispersive X-ray spectroscopy. The results show that ZnO is loaded on the surface of Co₃O₄ nanoparticles with a compact and clean hetero-interface. The obtained nanocomposites were tested for gas-sensing applications with ethanol and formaldehyde as model gases. It was revealed that the nanocomposites exhibit enhanced gas-sensing performance such as high stability and high sensing response. The sensing responses to 100ppm ethanol or formaldehyde (46 to ethanol and 20 to formaldehyde) are much higher than those of pristine Co₃O₄ nanoparticles (6.2 to ethanol and 4.4 to formaldehyde), commercial Co₃O₄ powder (1.6 to ethanol and 1.5 to formaldehyde), and pure ZnO sample (7.5 to ethanol and 4.1 to formaldehyde). These results suggest that the integration of Co₃O₄ with ZnO is a promising route to the development of effective sensing materials. The excellent gas-sensing properties and the easily up-scalable preparation route make the prepared nanocomposites be promising for real applications.

Keywords: ZnO; Co; ₃; O; ₄; p–n junction; Gas sensor; Nanocomposites

Mechanical stresses in silicon carbonitride films obtained by PECVD from hexamethyldisilazane by V.R. Shayapov; Yu.M. Rumyantsev; A.A. Dzyuba; B.M. Ayupov; N.I. Fainer (pp. 385-388).

► Mechanical stresses in PECVD silicon carbonitride films are mainly intrinsic. ► Volume changes in growing film correlate with PECVD mechanism. ► CTE and Young's modules of silicon carbonitride films are calculated.Silicon carbonitride films were obtained by PECVD method from hexamethyldisilazane at different deposition temperatures. Mechanical stresses in the films were studied by laser beam deflection method. It was found that the films deposited at low temperatures (below 400°C) are in compressive internal stresses because of the volume expansion of the growing film. Meanwhile, the films deposited at high temperatures (above 400°C) have tensile stresses due to volume contraction during deposition. In addition, the dependences of coefficient of thermal expansion and Young's modulus of the films on deposition temperature are obtained. The results are discussed in the light of known features of the deposition process and also chemical and phase composition of the films.

Keywords: Mechanical stresses; Film; PECVD; Silicon carbonitride

Structural analysis of nitride layer formed on uranium metal by glow plasma surface nitriding by Kezhao Liu; Ren Bin; Hong Xiao; Zhong Long; Zhanglian Hong; Hui Yang; Sheng Wu (pp. 389-392).

► The nitride layer was formed on uranium by glow plasma surface nitriding. ► Four zones were observed in the nitride layer. ► The chemical states of uranium, nitrogen, and oxygen were identified by AES.The nitride layer was formed on uranium metal by a glow plasma surface nitriding method. The structure and composition of the layer were investigated by X-ray diffraction and Auger electron spectroscopy. The nitride layer mainly consisted of α-phase U₂N₃ nanocrystals with an average grain size about 10–20nm. Four zones were identified in the layer, which were the oxide surface zone, the nitride mainstay zone, the oxide-existence interface zone, and the nitrogen-diffusion matrix zone. The gradual decrease of binding energies of uranium revealed the transition from oxide to nitride to metal states with the layer depth, while the chemical states of nitrogen and oxygen showed small variation.

Keywords: Uranium; Nitride layer; Glow plasma surface nitriding; X-ray diffraction; Auger electron spectroscopy

Preparation and characterization of ammonium-functionalized silica nanoparticle as a new adsorbent to remove methyl orange from aqueous solution by Jinshui Liu; Shi Ma; Lingjie Zang (pp. 393-398).

► QPEI/SiO₂ was utilized as an adsorbent. ► It was used for the removal of methyl orange (MO), an anionic dye from aqueous solution. ► The equilibrium time for methyl orange adsorption onto QPEI/SiO₂ was as short as 10min. ► The adsorption equilibrium was well described by the Langmuir isotherm model. ► The pH of the solution has a slight influence to adsorption capacity.Quaternary ammonium polyethylenimine (PEI) was successfully modified to silica nanoparticle (QPEI/SiO₂) as a new adsorbent to remove methyl orange from aqueous solution. The isotherm and kinetics of dye adsorption were studied, which showed that Langmuir isotherm fit the experimental results well. The maximum adsorption capacity of QPEI/SiO₂ for methyl orange is 105.4mg/g. The equilibrium time for methyl orange adsorption onto QPEI/SiO₂ was as short as 10min, indicating that the adsorbent has a strong affinity for methyl orange. The adsorption capacities of the methyl orange are slightly influenced by the pH in the range of 3.2–9.6. The QPEI/SiO₂ adsorbent can be used in the wide pH range, which is different from other adsorbent. This may attribute to the quaternary ammonium carrying positive charges in acidic and basic solution.

Keywords: Removal; Methyl orange; Polyethylenimine; Quaternary ammonium

Low-temperature growth of In_xGa1−_xN films by radio-frequency magnetron sputtering by J. Wang; X.J. Shi; J. Zhu (pp. 399-404).

Display Omitted► In_xGa1−_xN films were prepared by radio-frequency magnetron sputtering using an In–Ga alloy target. ► Grazing incidence X-ray diffraction peaks corresponding to wurtzite structure were observed. ► XPS and SIMS analysis indicates that the entire films have oxide phases. ► The optical transmittance spectra of the as-grown films show interference fringe patterns. ► Oxygen impurities formed amorphous oxide phases embedded in In_xGa1−_xN matrix.The low-temperature growth of In_xGa1−_xN films on quartz glass substrates utilizing radio-frequency magnetron sputtering is investigated. In the In_xGa1−_xN films prepared using an In–Ga alloy target, grazing incidence X-ray diffraction (GIXRD) peaks corresponding to wurtzite structure were observed. X-ray photoelectron spectroscopy (XPS) was applied to study the extent of oxygen contamination and chemical states, and secondary ion mass spectrometry (SIMS) was used to evaluate the distribution profiles of oxygen impurity in the as-grown In_xGa1−_xN thin films. XPS and SIMS analysis indicate that the entire thin films have oxide phases. However, no evidence of In₂O₃, Ga₂O₃, or indium oxynitride phases was shown in XRD studies. It may be predicted that the oxygen impurities formed amorphous oxide phases embedded in In_xGa1−_xN matrix. According to our findings, indium is a major phase in the In_xGa1−_xN thin films which suggests that a significant amount of indium remains un-reacted with N₂. The optical transmittance spectra of the as-grown films show interference fringe patterns. The indium fraction x of the as-deposited In_xGa1−_xN thin films can be calculated out by the transmittance data.

Keywords: In; _x; Ga; 1−; _x; N films; Grazing incidence X-ray diffraction (GIXRD); X-ray photoelectron spectroscopy (XPS); Secondary ion mass spectrometry (SIMS); Oxygen contamination

Facile fabrication of nano-structured silica hybrid film with superhydrophobicity by one-step VAFS approach by Yi Jia; Renliang Yue; Gang Liu; Jie Yang; Yong Ni; Xiaofeng Wu; Yunfa Chen (pp. 405-411).

Display Omitted► Superhydrophobic films on various substrates were fabricated by a novel one-step flame method. ► The samples could switch between superhydrophobic and superhydrophilic by varying a key process parameter. ► The effect of process parameters on the samples’ wettability were studied in detail. ► A reasonable flame reaction zone mechanism of this novel one-step method was proposed.Here we report a novel one-step vapor-fed aerosol flame synthesis (VAFS) method to attain silica hybrid film with superhydrophobicity on normal glass and other engineering material substrates using hexamethyldisiloxane (HMDSO) as precursor. The deposited nano-structured silica films represent excellent superhydrophobicity with contact angle larger than 150° and sliding angle below 5°, without any surface modification or other post treatments. SEM photographs proved that flame-made SiO₂ nanoparticles formed dual-scale surface roughness on the substrates. It was confirmed by FTIR and XPS that the in situ formed organic fragments on the particle surface as species like (CH₃)_xSiO2− x_/2 ( x=1, 2, 3) which progressively lowered the surface energy of fabricated films. Thus, these combined dual-scale roughness and lowered surface energy cooperatively produced superhydrophobic films. IR camera had been used to monitor the real-time flame temperature. It is found that the inert dilution gas inflow played a critical role in attaining superhydrophobicity due to its cooling and anti-oxidation effect. This method is facile and scalable for diverse substrates, without any requirement of complex equipments and multiple processing steps. It may contribute to the industrial fabrication of superhydrophobic films.

Keywords: One-step fabrication; Vapor-fed aerosol flame synthesis; Superhydrophobic surface; Silica hybrid film

Response of Si- and Al-doped graphenes toward HCN: A computational study by Somayeh F. Rastegar; Ali Ahmadi Peyghan; Nasser L. Hadipour (pp. 412-417).

► Sensitivity of Si- and Al-doped graphene (SiG and AlG) toward HCN is investigated. ► The electronic properties of AlG are significantly changed in the presence of HCN. ► It is established that AlG can be a good sensor for HCN molecule.Sensitivity of Si- and Al-doped graphenes (SiG and AlG) toward toxic HCN has been investigated using density functional theory (DFT) in terms of energetic, geometric and electronic properties. Optimized configurations corresponding to physisorption and, subsequently, chemisorption of HCN on each surface have been identified. It is found that HCN molecule can be adsorbed on impurity atoms with adsorption energies about −27.20 and −38.75kcal/mol on the SiG and the AlG, respectively. By comparing to HCN adsorption on SiG, it can be inferred that molecular HCN adsorbed on AlG can induce significant change in AlG conductivity. On the basis of calculated changes in the HOMO/LUMO energy gap it is found that electronic properties of AlG are sensitive toward adsorption of HCN and the reverse is correct for SiG, suggesting that the AlG may be a promising sensor for HCN.

Toughening effect of Ni on nc-CrAlN/a-SiN_x hard nanocomposite by Yu Xi Wang; Sam Zhang; Jyh-Wei Lee; Wen Siang Lew; Bo Li (pp. 418-423).

► Ni doped nc-CrAlN/a-SiN_x nanocomposite is synthesized via magnetron sputtering. ► Microstructure evolution of Ni doped nc-CrAlN/a-SiN_x is revealed. ► Toughening effect of Ni on hard nc-CrAlN/a-SiN_x nanocomposite is investigated.To combat the brittleness of hard nc-CrAlN/a-SiN_x nanocomposite (nc-: nanocrystalline, a-: X-ray amorphous), different Ni content (from 0 to 39.8at.%) is doped via magnetron sputtering. Glancing Angle X-ray Diffractometry, X-ray photoelectron spectroscopy, Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy are employed to investigate the microstructural evolution. With increased Ni, the grain size decreases accompanied with morphology change, from dense glassy to coarse columns. With 4.2at.% Ni, scratch toughness of nc-CrAlN/a-SiN_x hard nanocomposite (28GPa) is improved by around 200% at expense of only 18% hardness.

Keywords: Nanocomposite; Toughness; Nickel; Magnetron sputtering

Self-assembly and enhanced visible-light-driven photocatalytic activities of Bi₂MoO₆ by tungsten substitution by Hongguang Yu; Zhenfeng Zhu; Jianhong Zhou; Jing Wang; Junqi Li; Yanli Zhang (pp. 424-430).

Display Omitted► Different morphology of nanosheet-based Bi₂MoO₆ by W substitution is synthesized. ► Photocatalytic activity is closely related with shape, size and structure of sample. ► Our work opens new ideals to integrate the advantages of semiconductor materials.The different compositions of Bi₂MoO₆ by tungsten substitution have been successfully synthesized via a facile hydrothermal process in the absence of a surfactant. All W-doped Bi₂MoO₆ samples were composed of nanosheets with similar orthorhombic Aurivillius layered structures. Bi₂MoO₆ samples show different phases varied with W content. For the Bi₂MoO₆ samples with the different n_w values, their band gaps have changed obviously compared with Bi₂MoO₆ (2.69eV) and Bi₂WO₆ (2.75eV). The Bi₂MoO₆ by tungsten substitution exhibited good photocatalytic activity in degradation of Rhodamine-B under 500W Xe lamp light irradiation. When n_w value is 0.5, the sample has the highest photocatalytic activity for RhB photodecomposition under visible light irradiation. It shows that photocatalytic activities of Bi₂MoO₆ samples by W substitution are relevant to nanosheet morphology and size, the intrinsic layered structure, band gap and the W content.

Keywords: Bi; ₂; MoO; ₆; Tungsten substitution; Photocatalysis; Nanosheets; Hydrothermal method

Effect of high temperature oxidation prefab film on formation of micro-arc oxidation coatings on 6061aluminum alloy by Shen Dejiu; Zou Jie; Wu Lailei; Liu Fangfei; Li Guolong; Cai Jingrui; He Donglei; Ma Haojie; Jiang Guirong (pp. 431-437).

► The effect of prefab film on the initial stage of growth process of the MAO ceramic coatings was studied. ► The evolution processes of the micro-discharge and the surface morphology, and their relationship were studied. ► The prefab film promoted the rate of the evolution process of the surface morphology and micro-discharges. ► The prefab film and electrolyte composition, especially element P, participated in the growth process of the MAO coatings.Ceramic coatings were formed by micro-arc oxidation (MAO) on 6061aluminum alloy with and without a high temperature oxidation prefab film under a constant voltage. The effect of the high temperature oxidation prefab film on the initial stage of growth process of the MAO ceramic coatings was studied in this paper. The results showed that the prefab film decreased the arc starting voltage and the arc starting time of the micro-arc oxidation, and promoted the evolution processes of the micro-discharge and the surface morphology of the coating. The prefab film and electrolyte composition, especially element P, participated in the formation of the coatings. The growth process of the micro-arc oxidation ceramic coatings on specimens with the prefab film consists of four steps. The first step is the formation of grain type of oxide lumps, the second step is the spread of the lumps like little worms along the specimen surface, the third step is the formation of many network areas with a number of linear materials like little worms, and the fourth step is the development of network areas into a continuous layer. However, at the same period, the growth process of micro-arc oxidation ceramic coatings on the specimens without the prefab film consists of two steps. The first step is the formation of a little grain type of oxide lumps, and the second step is the increase of the number of grain type of oxide lumps and the expansion of the lumps like little worms in line along the surface of specimens.

Keywords: 6061aluminum alloy; High temperature oxidation prefab film; Micro-arc oxidation; Formation process

Enhanced performance of {001} facets dominated mesoporous TiO₂ photocatalyst composed of high-reactive nanocrystals and mesoporous spheres by Wei Wang; Chunhua Lu; Yaru Ni; Fengping Peng; Zhongzi Xu (pp. 438-442).

Display Omitted► Mesoporous {001} facets dominated TiO₂ sheets were prepared. ► High reactive nanocrystals and mesoporous spheres were introduced. ► High specific surface area was obtained. ► The role of N and F species were analyzed. ► The superior structure is very favorable for photocatalysis.{001} facets dominated mesoporous anatase TiO₂ sheets composed of mesoporous spheres and high reactive nanocrystals with exposed {001} facets were synthesized successfully with NH₄F as the capping agent by the hydrothermal and heat treatment method. The photocatalyst exhibits a high specific surface area and a higher photocatalytic activity than Degussa P25 and pure TiO₂ nanosheets in the degradation of organic dyes under UV irradiation.

Keywords: {0; 0; 1} facets; Titanium dioxide; Photocatalysis; Mesoporous; Specific surface area

Reaction mechanism for methanol oxidation on Au(111): A density functional theory study by Shuping Liu; Peng Jin; Donghui Zhang; Ce Hao; Xueming Yang (pp. 443-451).

Display Omitted► The methanol oxidation on Au(111) surface was studied by density functional theory computations. ► The esterification or oxidation of formaldehyde on Au(111) may depend on current oxygen coverage. ► Formaldehyde and methoxy will react to yield methyl formate with low oxygen coverage; in contrast, formaldehyde can oxidize to form formate with high oxygen coverage. ► The DFT results rationalize both of the experimental observations by Gong and Xu et al.The microscopic reaction mechanism for methanol oxidation on Au(111) surface has been thoroughly investigated by means of density functional theory (DFT) computations. The adsorption geometries and energies were obtained for all the adsorbates, including the reactants, the products, and various possible intermediates on the metal. According to different oxygen conditions, we propose two possible reaction pathways for methanol oxidation on Au(111): (1) HCHO esterification: the intermediate formaldehyde and methoxy couple to yield methyl formate at low oxygen coverage or without the presence of oxygen atoms; (2) HCHO oxidation: the formaldehyde is oxidized to form formate at high oxygen coverage, which further dissociates to give CO₂. Our study emphasizes the critical role of oxygen coverage during the methanol oxidation reaction, and can perfectly explain the difference in product distributions observed in previous experiments.

Keywords: Gold catalysis; Methanol; Oxidation; Esterification; Density functional calculations

Surface modification and biocompatible improvement of polystyrene film by Ar, O₂ and Ar+O₂ plasma by Yashao Chen; Qiang Gao; Haiyan Wan; Jinhong Yi; Yanlin Wei; Peng Liu (pp. 452-457).

Display Omitted► NVP is successfully grafted onto the different discharge gases (Ar, O₂, and Ar+O₂) plasma-treated PS film surface by Ar plasma induced graft polymerization. ► Compare with Ar and O₂ plasma, the Ar+O₂ plasma-treated film surface introduced large amounts of NVP, as known from ATR-FTIR and XPS results. ► According to SEM, the surface roughness increased at different levels after plasma treatment. Contact angle reveal that the hydrophilicity of the PS film surface was greatly improved. ► Cellular compatibility tests indicate that Ar+O₂ plasma is more capable of increasing cell adhesion and proliferation.This paper reports the surface modification of different discharge gases (Ar, O₂, and Ar+O₂) plasma-treated polystyrene (PS) film by Ar plasma induced graft polymerization, with biocompatible monomer N-vinyl-2-pyrrolidone (NVP) is carried out to improve biocompatibility. The films are characterized by attenuated total reflectance Fourier transfer infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Water contact angle measurement demonstrates the modified films possess a relatively hydrophilic surface. Furthermore, the films are also examined cell attachment and proliferation in vitro using mouse fibroblasts (L929 cells). The modified film surface shows a better cell distribution and growth than that of the pristine PS surface. From cell culture experiments, it is also observed that Ar+O₂ plasma is more capable of increasing cell adhesion and proliferation. This method will provide a potential and effective solution for grafting useful component in future tissue-engineering applications.

Keywords: Surface modiﬁcation; Plasma treatment; PS; NVP; Biocompatibility

Enhanced NH₃ gas sensing properties of a QCM sensor by increasing the length of vertically orientated ZnO nanorods by Vu Anh Minh; Le Anh Tuan; Tran Quang Huy; Vu Ngoc Hung; Nguyen Van Quy (pp. 458-464).

► Vertically aligned ZnO nanorods were directly synthesised on a substrate by a simple low-temperature hydrothermal method. ► Highly sensitive mass-type NH₃ gas sensor was fabricated by using QCM coated with ZnO nanorods. ► Increasing in the length of ZnO nanorods will increase the sensitive surface area and sensing characteristics.Vertically aligned ZnO nanorods were directly synthesised on a gold electrode of quartz crystal microbalance (QCM) by a simple low-temperature hydrothermal method for a NH₃ gas sensing application. The length of vertically aligned ZnO nanorods was increased to purpose enhancement in the gas sensing response of the sensor. The length of ZnO nanorods increased with an increase in growth time. The growth time of ZnO nanorods was systematically varied in the range of 1–4h to examine the effect of the length of the ZnO nanorods on the gas sensing properties of the fabricated sensors. The gas sensing properties of sensors with different ZnO nanorods lengths was examined at room temperature for various concentrations of NH₃ (50–800ppm) in synthetic air. Enhancement in gas sensing response by increasing the length of ZnO nanorods was observed.

Keywords: QCM; Gas sensors; ZnO nanorods; Hydrothermal method

Study of electrodepositing Au on hollow polystyrene microspheres by Jin Rong; Zhang Yunwang; Zhang Lin; Wei Chengfu; Guo Jianjun (pp. 465-469).

► The gold is electrodeposited on hollow polystyrene microspheres by self-designed setup in this paper. ► The Au electrodeposit is finer and more uniform on account of the microspheres freely move on the cathode. ► The morphology, thickness and roughness of Au electrodeposits were analyzed using Scanning Electron Microscopy, X-ray diffraction and Atomic Force Microscope, respectively.The electrodeposited Au film on hollow polystyrene microspheres is successfully prepared by a set of self-designed device. The film is more compact and uniform on account of the microspheres freely moving on the cathode. These experiments mainly focus on the analysis of spherical symmetry, thickness and roughness of electrodeposited Au film. Under conditions of current density 1.5–3mAcm⁻², the temperature 25°C, and the stirring rate 150rpm, the electrodeposited microsphere is coated with a considerably orbicular film. The morphology, thickness and roughness of Au electrodeposits are studied by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Atomic Force Microscope (AFM), respectively.

Keywords: Hollow polystyrene microspheres, Self-designed device, Au electrodeposit

Optical characterization of polysilazane based silica thin films on silicon substrates by Pier Carlo Ricci; Gianluca Gulleri; Francesco Fumagalli; Carlo Maria Carbonaro; Riccardo Corpino (pp. 470-474).

► Polysilazane based silica thin films (290nm) grown on multilayer structures of different ultra-thin barriers (UTBs) on silicon substrates were studied. ► The oxide local structure was studied in terms of SiOSi bridges by FTIR spectroscopy. ► The substrate–silica interfaces and the presence of defects were studied by means of steady state and time resolved luminescence. ► The analysis revealed the presence of dioxasilirane,Si(O₂), and silylene,Si:, defect centers in the samples grown on silicon nitride UTB.In this work polysilazane based silica thin films grown on multilayer structures of different ultra-thin barriers (UTBs) on silicon substrates were studied. The silica thin films were obtained by polysilazane spin coating deposition (also called SOD, spin-on dielectrics) upon different UTB liners (silicon nitride or silicon dioxide). By curing the SOD with thermal treatments the polysilazane is converted into silica thin films. The degree of conversion to SiO₂ was analyzed and the oxide local structure was studied in terms of SiOSi bridges by FTIR spectroscopy. Steady state and time resolved luminescence were applied to further characterize the oxide structure, the substrate–silica interfaces and the presence of defects. The analysis revealed the presence of dioxasilirane,Si(O₂), and silylene,Si:, defect centers in the samples grown on silicon nitride UTB, while these defects are not observed in samples grown on silicon oxide UTB.

Keywords: PACS; 71.55.−I; 71.55.Jv; 68.60.−p; 68.65.−kSilica thin film; Polysilazane; Ultra thin barriers; Spin-on dielectrics; SOD; FTIR; Photoluminescence; Structural properties; Surface defects; Dioxasilirane; Silylene

Synthesis, characterization and microwave properties of strontium hexaferrite thin films prepared by chemical bath deposition by Deepti V. Ruikar; P.B. Kashid; V.R. Patil; Vijaya Puri (pp. 475-479).

► Strontium hexaferrite thin films were successfully deposited on alumina by chemical bath deposition technique for the first time. ► For the first time it was observed that, the highly dense (synthesis pH 10) strontium hexaferrite thin films can be used as microwave transmitting material. ► These thin films also have very high microwave dielectric constant and very low loss.Strontium hexaferrite thin films were deposited on alumina by chemical bath deposition technique. The thin films formed with different synthesis pH were annealed by microwave heating. The effect of variation of pH of the solution during synthesis on the structural, morphological and microwave properties was studied by X-ray diffraction, scanning electron microscopy, waveguide reflectometer and slotted section technique. The strontium hexaferrite thin films synthesized at pH 10 show highly dense surface morphology and hence, high microwave transmittance of ∼65% in the 8–12GHz frequencies. With further increase in transmittance by tailoring the permittivity and permeability, these strontium hexaferrite thin films can be used as microwave transmitting material.

Keywords: Hexaferrite thin films; Chemical bath deposition; Crystal structure; Microwave transmittance

Bioinspired micro/nano fabrication on dental implant–bone interface by Feng Wang; Liang Shi; Wen-Xi He; Dong Han; Yan Yan; Zhong-Ying Niu; Sheng-Gen Shi (pp. 480-488).

Display Omitted► We analyzed the natural hierarchical micro/nano structure in rat's alveolar bone. ► We developed a novel way to fabricate a biomimetic dental implant–bone interface. ► TiO₂ nanotubes on pit-like microscale Ti implant's surface showed a superior property. ► This bioinspired dental implant's surface can provide a better bioactivity.Pioneering research suggests fabricating a biomimetic interface with multiscaled surfacial architecture can greatly improve biomaterials’ function and property. According to this inspiration, we chiefly single out and analyze the natural hierarchical micro/nano structure in rat's alveolar bone. Then, a combined hierarchical structure, i.e. micro-pits interlaced self-assemble TiO₂ nanotubes of several tens of nanometers on dental implant's surface is developed. The as-prepared surface showed that hundreds of self-assembled TiO₂ nanotubes were tightly arrayed with a diameter range of 30–50nm, similar to collagen fibers within rat's mandible (60–80nm). Meanwhile, this hierarchical micro/nano surface can provide a larger surface energy and roughness, a preferable hydrophilicity, a more adaptive mechanical property and adhesion work, a better bioactivity and biocompatibity, a superior attachment and growth of osteoblasts as compared to the smooth and purely micro-treated counterparts. The results indicated that this bioinspired micro/nano fabrication on dental implant–bone interface can be potentially applied in the update of dental implant in patients’ clinical therapy and provide a new strategy for fabricating other osteocompatible materials.

Keywords: Bioinspired; Dental implant; Micro/nano fabrication; TiO; ₂; nanotube; Surface modification

Differential ion beam sputtering of segregated phases in aluminum casting alloys by Chuong L. Nguyen; Tom Wirtz; Yves Fleming; James B. Metson (pp. 489-494).

Display Omitted► Novel combination of SIMS and SPM for accurate 3D chemical mapping. ► Different removal rates of metallurgical phases by ion beam. ► Faster oxidation rate of silicon vs. aluminum at room temperature in vacuum.Differential sputtering of materials is an important phenomenon in materials science with many implications. One of the practical applications of this phenomenon is the modification of the interface between a substrate and coating during sputter coating of materials. Aluminum casting alloys, as common materials in many applications, are suitable candidates to investigate this phenomenon due to their phase separated microstructures.Changes at the sample surface under ion bombardment can be characterized by a range of complimentary techniques. The novel SIMS–SPM instrument used here enables a thorough investigation into the evolution of topography and composition caused by ion beam sputtering. For the alloy examined in this work, the aluminum regions are removed faster than the silicon particles. The faster oxidation rate of silicon compared to aluminum in the exposed surface can also be deduced from this study.

Keywords: Secondary ion mass spectrometry (SIMS); X-ray photoelectron spectroscopy (XPS); Scanning probe microscopy (SPM); Interface; Oxide-film growth kinetics; 3-Dimensional mapping

On the interfacial interaction between bituminous binders and mineral surfaces as present in asphalt mixtures by Hartmut R. Fischer; E.C. Dillingh; C.G.M. Hermse (pp. 495-499).

► Direct measurement of the contact angle between different phases of the microstructure of bitumen and aggregate surfaces of different chemical nature using AFM. ► Common schema of adhesion of bitumen on aggregates via asphaltene precipitation. ► Surface roughness/porosity more important than chemical nature for strength of adhesion between aggregate and bitumen.The interfacial interaction between bituminous binders and several mineral surfaces of different chemical nature as present in asphalt mixtures has been investigated using atomic force microscopy. Several dry mineral surfaces display comparable wetting with respect to the different phases present in the micro-structure of bitumen, regardless of differences in their chemical nature. The peri/catana-phase shows a preferential wetting due to adsorption of asphaltene aggregates to the mineral surfaces.

Keywords: Asphalt adhesion; Bitumen microstructure; AFM; Contact angle; Wetting

Preparation of palladium nanoparticles on alumina surface by chemical co-precipitation method and catalytic applications by Avvaru Praveen Kumar; B. Prem Kumar; A.B.V. Kiran Kumar; Bui The Huy; Yong-Ill Lee (pp. 500-509).

Display Omitted► Facile synthesis of palladium nanoparticles on alumina surface. ► The surface morphology and properties of the nanocrystalline powders were characterized. ► The catalytic activities of palladium nanoparticles were investigated.The present work reports a chemical co-precipitation process to synthesize palladium (Pd) nanoparticles using alumina as a supporting material. The optimized temperature for the formation of nanocrystalline palladium was found to be 600°C. The X-ray diffraction (XRD) and Raman spectroscopy were used to study the chemical nature of the Pd in alumina matrix. The surface morphology and properties of the nanocrystalline powders were examined using thermogravimetric analysis (TG–DTA), XRD, Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The calcinations in different atmospheres including in the inert medium forms the pure nano Pd⁰ while in the atmospheric air indicates the existence pure Pd⁰ along with PdO nanoparticles. The catalytic activities of the as-synthesized nanocrystalline Pd nanoparticles in the alumina matrix were investigated in Suzuki coupling, Hiyama cross-coupling, alkene and alkyne hydrogenation, and aerobic oxidation reactions.

Keywords: Palladium nanoparticles; Chemical co-precipitation; Surface morphology; Catalytic applications

Structure, morphology and optical properties of multilayered sol–gel BaTi_0.85Zr_0.15O₃ thin films by Cătălina A. Vasilescu; Maria Crişan; Adelina C. Ianculescu; Mălina Răileanu; Măriuca Gartner; Mihai Anastasescu; Nicolae Drăgan; Dorel Crişan; Raluca Gavrilă; Roxana Truşcă (pp. 510-518).

.Display Omitted► Multilayered BaTi_0.85Zr_0.15O₃ sol–gel films coated on silicon wafers were performed. ► Structure, surface topography and optical properties were investigated. ► Perovskite BTZ phase were noted only in the thicker multilayer films (BTZ4–BTZ6). ► A smaller roughness value was obtained for the six deposits BTZ film. ► Multilayer BTZ films present a more uniform distribution of the average grain size.Continuous and homogeneous multilayered BaTi_0.85Zr_0.15O₃ (BTZ) films were prepared by the sol–gel method and deposited on SiO₂/Si substrates. X-ray diffraction analysis indicated the presence of well-crystallized, single phase perovskite BTZ phase only in the thicker, multilayer films (with more than three deposits). Beside the shrinkage of the unit cell, the increase of the deposits number in the BTZ films also induced an obvious surface smoothing, a higher compactness and a more uniform distribution of the average grain size, as observed by SEM and AFM investigations. The refractive index showed normal values indicating a high crystallinity degree for the films under investigation.

Keywords: Ba(Ti,Zr)O; ₃; film; Sol–gel; Perovskite; Optical properties; Microstructure

The influence of the short-term ultraviolet radiation on the structure and properties of poly( p-phenylene terephthalaramide) fibers by Shineng Li; Aijuan Gu; Jie Xue; Guozheng Liang; Li Yuan (pp. 519-526).

Display Omitted► The effect of the short-term UV radiation on properties of PPTA fibers was studied. ► The properties include surface properties, mechanical and thermal resistance. ► Surfaces of radiated fibers are rougher and have more oxygen-based functional groups. ► Radiation does not change the chemistry and crystalline structure of fiber core. ► The structure-property relation of PPTA fibers during the UV radiation was build.The influence of the short-term (<20h) ultraviolet (UV) radiation (at 60±3°C with a relative humidity of 50±1 RH%) on the integrated performance of poly( p-phenylene terephthalaramide) fibers was comprehensively studied, and the mechanism behind the influence was intensively discussed by detecting the overall changes in both chemical and morphological structures. Results demonstrate that the short-term UV radiation has different effect on the core part from the surface part of PPTA fibers. Specifically, the short-term UV radiation slightly decreases the crystalline index without changing the chemical structure of the core part of PPTA fibers; while that introduces a large amount of oxygen atoms on the surfaces of UV-KF fibers, and induces a distinctive increase in the surface roughness of fibers even the irradiation time is only 1h. These structural changes make UV-KF fibers show decreased contact angle and improved wettability while remaining the outstanding glass transition temperature. All parameters of tensile properties including tenacity, break extension, energy to break and modulus almost linearly decrease as the irradiation time extends; however, these parameters almost level off when the irradiation time is longer than 3h. After irradiated for 18h, the tenacity, break extension, energy to break of UV-KF fiber is 88%, 90%, and 86% of the corresponding value of original fiber, respectively.

Keywords: Short-term ultraviolet radiation; Poly(; p; -phenylene terephthalaramide) fibers; Surface; Structure; Property

A homogeneous Ni–P coating with a unique scalelike structure deposited on VGCNFs by an electroless deposition method by Ju Hyung Kim; Jae Deuk Kim; Hoon Mo Park; Sang Bok Lee; Jin Woo Yi; Seung Il Jung (pp. 527-531).

Display Omitted► Ni–P coated VGCNFs with a scalelike and mesoporous structure were fabricated. ► The as-prepared Ni–P/VGCNFs composite has a large surface area of 74.2m²/g. ► With low phosphorus content, the composite was amorphous mixed with crystalline. ► The Ni–P coating and VGCNFs mutually affect each other's oxidation temperature.A unique scalelike structured Ni–P alloy coated vapor-grown carbon nanofibers (VGCNFs) were fabricated by an electroless deposition method following pre-treatment of activation. The coating was found to be homogeneous and mesoporous. The scalelike structure gives the composite material a very high surface area of 74.2m²/g, significantly higher than the only reported scalelike structured Ni–P/CNFs catalyst. Hence, it is suggested to have great potential in wide applications, especially catalysts. A relatively low level of phosphorus content was discovered, which result in a mixture of amorphous and crystalline in the initial state. Moreover, our results show that the Ni–P coating and VGCNFs have an interaction effect on the oxidation temperature of each other.

Keywords: VGCNFs; Ni–P; Scalelike; Electroless deposition

Preparation of superhydrophobic coating using modified CaCO₃ by Yansheng Zheng; Yi He; Yongquan Qing; Chuanbo Hu; Qian Mo (pp. 532-536).

► The coating showed the water contact angle of 160° and the water sliding angle of 6°. ► The hierarchical structure with the low surface energy leads to surface superhydrophobicity. ► We demonstrated a simple yet efficient approach for preparing superhydrophobic surface.CaCO₃ nanoparticles were modified from hydrophilic to hydrophobic with oleic acid, hydrophobic coating was formed on the glass substrates with modified nanoparticles and polydimethylsiloxane via a simple process. The surface wettability and topology of coating were studied by contact angle measurement and scanning electron microscopy. The experimental results showed that the coating exhibited self-cleaning property with a water average contact angle of 160° and sliding angle of 6°, coating surface with hierarchical nano and micro structures, this method has good prospect for applications.

Keywords: Nano-sized CaCO; ₃; Oleic acid; Polydimethylsiloxane; Superhydrophobicity

Effects of cathodic current density and temperature on morphology and microstructure of iridium coating prepared by electrodeposition in molten salt under the air atmosphere by Li’an Zhu; Shuxin Bai; Hong Zhang; Yicong Ye (pp. 537-545).

► The “salt passivation” occurs on the anode surface at low temperatures. ► The index of preferred growth crystal plane increases as increasing current density. ► The <111> oriented coating is smoother and denser than <220>/<311> oriented coating. ► The coating compactness improves as increasing current density/decreasing temperature.Iridium coating was prepared on a Re/C substrate (graphite substrate coated with rhenium coating by CVD) using electrodeposition in molten salt of chlorides in the air atmosphere. The effects of cathodic current density and temperature on both the morphology and microstructure of the coating were studied, respectively. The morphology and orientation of the coating were determined by scanning electron microscope and X-ray diffraction, respectively. The results showed that the cathodic current density and temperature both affected the surface morphology, roughness, grain size and compactness of the iridium coating. With increasing of current density from 5 to 50mA/cm², the surface roughness of the coating increased from Ra 0.98 to Ra 6.29μm, while the grain size decreased. With temperature increasing from 520 to 640°C, the surface roughness of the coating decreased from Ra 4.41 to Ra 1.16μm, while the grain size increased. The preferred orientations of the coatings changed in the row <111>–<220>–<311> with current density increasing. With the increase of temperature, the preferred orientation of the coating changed from <111> to <220>, and again to <111>. The coating with <111> orientation was smoother and denser than that with <220> orientation regardless of the grain size.

Keywords: Iridium coating; Microstructure; Orientation; Molten salt; Electrodeposition; Air atmosphere

Hydrophobic and ice-retarding properties of doped silicone rubber coatings by F. Arianpour; M. Farzaneh; S.A. Kulinich (pp. 546-552).

► Superhydrophobic coatings were prepared of silicone rubber doped with different nanoparticles. ► Freezing of small water droplets on different hydrophobic surfaces was followed. ► A correlation between surface wetting hysteresis and faster freezing of water was observed.In this study, room-temperature vulcanized silicone rubber coatings were prepared by spin-coating hexane-diluted suspensions onto aluminum substrates. Various amounts of carbon-black, titania or ceria nanopowders were incorporated to the coatings as dopants in order to modify their surface roughness, hydrophobic and electrical properties. By changing deposition parameters, superhydrophobic surfaces could be prepared. The freezing behavior of small water droplets was investigated on nanostructured composite surfaces exhibiting different values of wetting hysteresis and was compared with that on uncoated polished aluminum. At approximately −15°C, the water droplets were found to freeze on polished aluminum after approximately 5s, while their freezing was delayed to as long as ∼12–13min on superhydrophobic nanocomposite surfaces doped with ceria or titania powders. Correlations between the wetting hysteresis (and surface roughness) of the samples and freezing time of water droplets on their surfaces were also observed. Icing tests demonstrated delayed ice formation and lower adhesion strength on superhydrophobic samples with small wetting hysteresis.

Keywords: PACS; 68.35.Md; 68.08.Bc; 82.45.MpSilicone rubber; Nanoparticles; Hydrophobicity; Freezing; Ice repellency

Morphology evolution of a-plane ZnO films on r-plane sapphire with growth by pulsed laser deposition by Chun-Yen Peng; Jr-Sheng Tian; Wei-Lin Wang; Yen-Teng Ho; Li Chang (pp. 553-557).

► Distinct evolution of surface morphologies for a-plane ZnO grown on r-plane sapphire at low and high temperatures is reported. ► (1×2) reconstruction occurs with step-flow growth was observed for ZnO grown at 750°C (HT-ZnO). ► ZnO grown at 450°C (LT-ZnO) shows island growth mode for initial growth. ► Significant change of surface morphology while cooling process had been observed by in situ RHEED. ► Both HT- and LT-ZnO films evolve into stripe morphology for thick film. (>100nm).In this study, the morphology evolution of epitaxial a-plane ZnO on r-plane sapphire at low and high temperatures with growth by pulsed laser deposition (PLD) are presented. Examination of the surfaces of ZnO films during growth was done with in situ reflection high energy electron diffraction, and atomic force microscopy was used to examine the surface morphology of the corresponding films after growth. For initial growth, it was observed that (1×2) reconstruction on ZnO grown at 750°C (HT-ZnO) occurred with step-flow growth, while ZnO grown at 450°C (LT-ZnO) exhibited island growth mode. For thick films both HT- and LT-ZnO surfaces eventually develop into stripe morphology. Significant change of surface morphology during cooling had also been observed.

Keywords: ZnO; Morphology; Epitaxial growth

RF-plasma vapor deposition of siloxane on paper. Part 1: Physical evolution of paper surface by Halil Turgut Sahin (pp. 558-563).

► Investigate the detailed RF cold plasma surface modified paper by water contact angle, SEM, AFM, water absorptivity and air permission tests. ► Some mechanical and physical analysis of RF-cold plasma surface modified paper after RF plasma treatment. ► Identify properties of RF cold plasma surface modified paper were investigated with water contact angle measurements.An alternative, new approach to improve the hydrophobicity and barrier properties of paper was evaluated by radio-frequency (RF) plasma octamethylcyclotetrasiloxane (OMCTSO) vapor treatment. The interaction between OMCTSO and paper, causing the increased hydophobicity, is likely through covalent bonding. The deposited thin silicone-like polymeric layer from OMCTSO plasma treatment possessed desirable hydrophobic properties. The SEM micrographs showed uniformly distributed grainy particles with various shapes on the paper surface. Deposition of the silicone polymer-like layer with the plasma treatment affects the distribution of voids in the network structure and increases the barrier against water intake and air. The water absorptivity was reduced by 44% for the OMCTSO plasma treated sheet. The highest resistance to air flow was an approximately 41% lower air permeability than virgin paper.

Keywords: Paper; RF plasma; Barrier properties; SEM; AFM; Tensile strength

RF-plasma vapor deposition of siloxane on paper. Part 2: Chemical evolution of paper surface by Halil Turgut Sahin (pp. 564-569).

► Investigate the detailed RF-cold plasma surface modified paper by XPS and ATR-FTIR. ► Some chemical analysis of RF-cold plasma surface modified paper after RF plasma treatment. ► Identify the connection between RF plasma treatment and the surface chemistry of paper surface.Survey and high-resolution (HR) XPS studies indicate that OMCTSO plasma treatment created a new silicon containing functional groups and changed the hydroxyl content on the surface of paper. Four intense survey XPS spectrum peaks were observed for the OMCTSO plasma treated paper. They were the Si_2p at 100eV, Si_2s at 160eV, C_1s at 285eV, and O_1s at 525eV for the plasma modified surface. It was realized that the macromolecular chain-breaking mechanisms and plasma-induced etching processes control the number and the availability of OH-functionalities during OMCTSO plasma exposure on paper. The reaction, initiated by these species, depends mainly on the nature of chemicals in the plasma as well as on the energy level of the plasma and the nature of the surface effects in the modification of the paper. The ATR-FTIR spectrum of paper treated with OMCTSO plasma has characteristic absorption bands attributed to the SiO and SiOSi formations on the surface.

Keywords: Paper; RF plasma; Octamethylcyclotetrasiloxane; XPS; Surface chemistry

Study of polymer–magnetic electrode interfaces using XPS by N.A. Morley; H.R.H. Al Qahtani; M.H. Hodges; M.R.J. Gibbs; M. Grell; V. Dediu; D.J. Morgan (pp. 570-577).

► Poly(3-hexylthiophene) forms stronger bonds on oxide rich surfaces compared to non-oxide surfaces. ► The bonding at a polymer–magnetic interface depends on the solvent (chloroform or toluene) the polymer is spin-coated in. ► RR-P3HT bonds stronger to the LSMO electrode surface than to transition metal surfaces.Organic spintronics studies spin carrier transportation through organic semiconductors. Understanding how to control this spin current within devices is an important step forward within the research area. The study of the interfaces between the magnetic electrodes and the organic semiconductor (known as the “spinterface”) to obtain efficient carrier injection and extraction is important. In this work, the bonding at the spinterface between the magnetic electrode and the polymer regio-regular poly(3-hexylthiophene) (RR-P3HT) has been studied using x-ray photoelectron spectroscopy (XPS). It was found that the bonding between the magnetic electrode and the RR-P3HT depended on both the nature of the magnetic electrode and the solvent used to spin-coat the RR-P3HT. The results are collated with the magnetoresistance measurements made on polymeric spin valve devices.

Keywords: Organic spintronics; Interfaces; RR-P3HT; XPS

Surface plasmon resonance induced reduction of high quality Ag/graphene composite at water/toluene phase for reduction of H₂O₂ by Feng-Jun Zhang; Ke-Hua Zhang; Fa-Zhi Xie; Jin Liu; Hong-Fei Dong; Wei Zhao; Ze-Da Meng (pp. 578-584).

► The Ag/graphene composites have been successfully synthesized in two-phase solvent. ► The surface plasmon resonance of Ag can reduce GO with high deoxygenation and low defect. ► The Ag particles were uniformly distributed on graphene surface. ► The Ag/graphene composites obtained show high superior electrical properties for reduction of H₂O₂.Surface plasmon resonance induced synthesis of Ag/graphene composites from Ag/graphene oxide (Ag/GO) in a two-phase (water–toluene) solvent was reported. Transmission electron microscopy (TEM) results revealed that the Ag nanoparticles with size of 5–8nm were trimly distributed on reduced graphene oxide sheets. Raman and X-ray photoelectron spectroscopy (XPS) have demonstrated low defect density and high deoxygenation degree of graphene in Ag/graphene composite. The excellent structure and morphology of Ag/graphene composites contributed to superior electrical properties for reduction of H₂O₂.

Keywords: Surface plasmon resonance; Ag/graphene; Reduction of H; ₂; O; ₂; Electrical properties

Infrared spectroscopic evidence of a direct addition reaction between palygorskite and pyromellitic dianhydride by Wenchang Yan; Peng Yuan; Ming Chen; Linjiang Wang; Dong Liu (pp. 585-590).

Display Omitted► A direct addition reaction between palygorskite and pyromellitic dianhydride. ► The graft of anhydride to the bound water on the external surface of palygorskite. ► Application of palygorskite without organo-modification.Palygorskite covalently grafted with pyromellitic dianhydride was investigated. Untreated and grafted samples were characterized by X-ray diffraction, thermogravimetry, and Fourier transform infrared spectroscopy. Infrared results showed the direct grafting of anhydride onto the bound water molecules on the external surfaces of the palygorskite. The grafting modification makes palygorskite more readily compatible with anhydride, resulting in substantial enhancements in the glass transition temperature and flexural strength of the anhydride-cured epoxy resin/palygorskite nanocomposites.

Keywords: Palygorskite; FTIR; Anhydride; Epoxy resin; Nanocomposites

Simple and large scale refluxing method for preparation of Ce-doped ZnO nanostructures as highly efficient photocatalyst by M. Rezaei; A. Habibi-Yangjeh (pp. 591-596).

A simple method was applied for the preparation of Ce-doped ZnO nanostructures (mole fractions of Ce⁴⁺ ions are 0, 0.025, 0.05, 0.075 and 0.10) in water by refluxing for 3h about at 90°C.Display Omitted► A simple refluxing method was applied for preparation of Ce-doped ZnO nanostructures. ► The XRD patterns demonstrate that loading of Ce⁴⁺ ions does not change the structure of ZnO. ► The results indicate that the nanostructures with 0.05 mole fraction of Ce⁴⁺ ions exhibit highest photocatalytic activity. ► The nanostructures have highest photocatalytic activity at solutions with pH between 5.4 and 9.A simple method was applied for preparation of Ce-doped ZnO nanostructures (mole fractions of Ce⁴⁺ ions are 0, 0.025, 0.05, 0.075 and 0.10) in water by refluxing for 3h about at 90°C. This method is large scale, mild and involve no templates, surfactants or additives. The prepared nanostructures were investigated by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–vis diffuse reflectance spectroscopy (DRS) techniques. The XRD patterns demonstrate that the nanostructures have the same crystal structure, and loading of Ce⁴⁺ ions does not change the structure of ZnO. The SEM images show that with increasing mole fraction of Ce⁴⁺ ions, morphology of the nanostructures changes from nanoplates to nanospheres. Photocatalytic activity of the nanostructures toward photodegradation of methylene blue (MB) was evaluated under UV irradiation. The results indicate that the nanostructures with 0.05 mole fraction of Ce⁴⁺ ions exhibit highest photocatalytic activity among the prepared samples. The influence of various operational parameters such as refluxing time, catalyst weight, calcinations temperature and pH of solution on the photodegradation reaction was studied. The optimum value for calcinations temperature was found to be at 400°C. Moreover, the nanostructures have highest photocatalytic activity at solutions with pH between 5.4 and 9.

Keywords: Ce-doped ZnO; Photocatalysis; Nanostructures; X-ray diffraction

Facile fabrication of superhydrophobic surfaces on zinc substrates by displacement deposition of Sn by Ling Cao; Jun Liu; Wei Huang; Zelin Li (pp. 597-602).

The tin dendrite surface prepared by a displacement reaction between a Zn plate and an acidic SnCl₂ solution showed superhydrophobicity without any surface modification.Display Omitted► Fabrication of stable superhydrophobic Sn surfaces by a displacement reaction. ► The highest water contact angle was 156° without any surface modification. ► The superhydrophobicity was related with the formation of Sn dendrites. ► The water droplet occurred in Cassie state on the surface of Sn dendrites. ► This procedure is facile, time-saving and cheap.Facile preparation of superhydrophobic surfaces of stable and cheap metals is practically important. We report here our findings on fabrication of a superhydrophobic metal Sn surface, which can be obtained at room temperature in 5min through a displacement reaction between a zinc plate and an acidic SnCl₂ solution without needing post-treatment and surface modification. This procedure is facile, time-saving and inexpensive, which is superior to other known displacement depositions of Pt, Ag, Au, or Cu. The effects of preparation conditions on the surface morphology and wettability have been investigated in detail, including reactant concentration and reaction time. It has been observed that superhydrophobicity was closely related with the morphological transition from tin nanoparticles/nanopores to tin dendrites, and the maximal water contact angle (CA) was about 156° with the Cassie state. We expect that this fabrication technique will find practical applications.

Keywords: Zn plate; Sn dendrite; Displacement reaction; Superhydrophobicity

Preparation of anti-oxidative SiC/SiO₂ coating on carbon fibers from vinyltriethoxysilane by sol–gel method by Kedong Xia; Chunxiang Lu; Yu Yang (pp. 603-609).

► The SiC/SiO₂ coating was prepared on carbon fibers by the sol–gel method. ► Nano-crystallites with an average diameter of 130nm were aligned along the fiber axis uniformly. ► The oxidation resistant property of coated carbon fiber was increased with the increase of sol concentration and the heat treatment temperature. ► The oxidation activation energy of the coated carbon fiber was increased by 23% in comparison with uncoated carbon fiber.The anti-oxidative SiC/SiO₂ coating was prepared on carbon fibers by a sol–gel process using vinyltriethoxysilane (VTES) as the single source precursor. The derived coating was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The oxidation resistant properties of the carbon fiber with and without coating were studied by isothermal oxidation. The results indicated that the carbothermal reduction reaction led to the decrease of SiO₂ phase and the increase of SiC phase at 1500°C. The uniform SiC/SiO₂ coating prepared from a sol concentration of 4wt% and heat treated at 1500°C showed the optimal oxidation resistant property. The oxidation resistance of the carbon fiber was improved by the SiC/SiO₂ coating, and the oxidation activation energy was increased by about 23% as compared with uncoated carbon fiber.

Keywords: Oxidation resistance; SiC/SiO; ₂; coating; Carbon fiber; Sol–Gel

Selective laser densification of lithium aluminosilicate glass ceramic tapes by Andrea Zocca; Paolo Colombo; Jens Günster; Thomas Mühler; Jürgen G. Heinrich (pp. 610-614).

► Selective laser densification of glass-ceramic tapes has been investigated. ► A possible application to the layerwise-slurry deposition process was evaluated. ► The effect of a few percent organic in the slurry was also studied. ► A range of parameters was identified to densify layers without macroscopic defects.Tapes, cast by blade deposition of a lithium aluminosilicate glass slurry, were sintered using a YAG-fiber laser, with the aim of finding suitable parameters for an additive manufacturing process based on layer-wise slurry deposition and selective laser densification. The influence of the laser parameters (output power and scan velocity) on the sintering was evaluated, by scanning electron microscopy and by X-ray diffraction, on the basis of the quality of the processed layer. Well densified samples could be obtained only in a small window of values for the output power and the scan velocity. The measurement of the width of a set of single scanned lines allowed also to estimate the minimum resolution of the system along the layer plane.

Keywords: Selective laser sintering (SLS); Layerwise-slurry-deposition (LSD); Glass-ceramic; LAS

Indirect interaction in Ag and Pd adsorbed layers on the Mo(112) surface by J. Śliwiński; M. Wiejak; J. Kołaczkiewicz; I.N. Yakovkin (pp. 615-620).

► The structure of Ag/Mo(112) has been studied by LEED. ► DFT calculations show that adjacent Ag or Pd adatoms attract each other. ► The missing-row p(1×2) Pd structure is formed due to indirect interaction. ► The corresponding period of Friedel oscillations is originated by surface sheets of Fermi surface of Mo(112).The structures of Ag adsorbed layers on the Mo(112) surface have been studied by low energy electron diffraction (LEED) and compared with Pd structures on this surface. Performed DFT calculations have shown that the dominant interaction at low coverages both in Ag and Pd layers is an attraction of adjacent adatoms, which explains the formation of atomic rows lying in the substrate furrows. The sheets of Fermi surface of Mo(112) originated by surface bands provide the period of Friedel oscillations approximately equal to 2 lattice periods in the direction normal to the furrows, which leads to the appearance of the minimum of the potential of the indirect lateral interaction at this distance and, for Pd coverage θ=0.5, results in the formation of the missing-row p(1×2) structure. The absence of the missing-row structure for the same coverage of Ag is caused by the incoherence of Ag chains with the substrate, which stems from the larger diameter of Ag adatoms.

Keywords: Low-energy electron diffraction; Ag and Pd adsorbed layers; Low-index transition metal surfaces; Density functional calculations

High-rate and low-temperature growth of ZnO:Ga thin films by steered cathodic arc plasma evaporation by Chih-Hao Liang; Wei-Lin Wang; Weng-Sing Hwang (pp. 621-629).

► ZnO:Ga (GZO) films are deposited on glass by steered cathodic arc plasma evaporation. ► GZO films are grown at a high growth rate (220nm/min) and low temperature (120°C). ► Films with low strain show low resistivity and high transparency. ► Droplet size is reduced when a high-melting-point GZO ceramic target is adopted. ► Metal-like conductivity indicates GZO films became degenerated semiconductors.Ga-doped ZnO (GZO) thin films with various thicknesses (120–520nm) are deposited on the glass substrate at a high growth rate of 220nm/min and a low temperature of 120°C by a steered cathodic arc plasma evaporation (steered CAPE). The growth mechanism, microstructure, residual stress, surface morphology, electrical and optical properties, chemical states, electron transport behaviors and thickness effect of the GZO films are investigated. The film stress is gradually relaxed from −0.516GPa to −0.090GPa with thickness increasing. Transmission electron microscopy (TEM) images show that the GZO microstructure consists of c-axis textured columnar grains accompanied by some embedded nanodroplets. The droplet size is significantly reduced when a high-melting-point (1975°C) GZO ceramic target is adopted. High-resolution TEM image shows the GZO crystallites nucleated directly onto the amorphous substrate. The electrical properties improve with increasing thickness. The lowest resistivity (4.72×10⁻⁴Ωcm) is achieved at the thickness of 520nm, with a corresponding transmittance of 89% in the visible region. Temperature-dependent resistivity measurements show that metal-semiconductor transition temperature increases from 136K to 225K when decreasing the thickness, which is due to the increasing the localized states caused by the defects and chemisorbed oxygen in thinner film.

Keywords: ZnO:Ga thin films; Steered cathodic arc plasma evaporation; Oxide conductor; Transparent electrode

Development of an opto-hydrodynamic process to remove nanoparticles from solid surfaces by Daehwan Ahn; Jeonghong Ha; Dongsik Kim (pp. 630-636).

► A pulsed micro-liquid jet can be produced by using the optical breakdown of a micro droplet. ► The speed of laser-induced micro liquid jet is up to 1600m/s. ► Nanoscale contaminants are removed by the direct impingement of the micro liquid jet and the resultant surface flows. ► 10nm alumina particles on the Si substrate are completely removed.We developed a surface cleaning process to remove nanoscale contaminants as small as 10nm from solid surfaces using a laser-induced micro liquid jet. In the process, laser-induced breakdown of a micron-sized water droplet (∼10nl) produces a high-speed jet with speeds up to 1600m/s liquid jet via an explosive vaporization process. Impingement of the liquid jet with atomized droplets on the contaminated substrate removes the nanoparticles under the hydrodynamic drag forces. The process parameters, including the incident laser energy and the position of the droplet relative to the laser focus, were optimized to maximize the cleaning power. Polystyrene latex particles 20, 30, or 90nm in diameter and Al₂O₃ particles 10–50nm in diameter were used to demonstrate the cleaning performance of the opto-hydrodynamic cleaning technique. The proposed cleaning process is expected to be useful for selectively cleaning local areas with minimal exposure to water.

Keywords: Laser cleaning; Laser-induced breakdown; Micro liquid jet; Opto-hydrodynamicsPACS; 42.62.Cf; 81.65.Cf; 52.50.Jm

Effects of nanosecond laser irradiation on photoelectric properties of AZO/FTO composite films by Bao-jia Li; Ming Zhou; Ming Ma; Wei Zhang; Wan-yi Tang (pp. 637-641).

► AZO/FTO films with better photoelectric properties were prepared by sputtering. ► The AZO/FTO films were irradiated by a nanosecond pulsed laser. ► The films treated by laser with suitable parameters achieved good annealing effects. ► The photoelectric properties of the films were improved by laser annealing process.The aluminum-doped zinc oxide (AZO) films were deposited on commercial fluorine-doped tin oxide (FTO) films with glass substrates by direct current magnetron sputtering. Thus, some AZO/FTO composite films with better photoelectric properties were obtained. The AZO/FTO films were irradiated by a nanosecond pulsed laser with a wavelength of 532nm. The variations of optical transmittance and electrical conductivity for the films irradiated by using various laser parameters were investigated. As experimental results show, the AZO/FTO films subjected to laser treatment with lower laser fluences and higher scan speeds achieved obvious laser annealing effects, so that the optical transmittance increased and the sheet resistance decreased. Conversely, all the films irradiated by using too high laser fluences or too low scan speeds were damaged, which resulted in the remarkable drop of optical transmittance and electrical conductivity. The laser fluence of 1.02J/cm² and the scan speed of 10mm/s were the optimal laser parameters in this study.

Keywords: Nanosecond laser; AZO/FTO composite film; Annealing; Photoelectric property

TOF-SIMS study on surface modification of reed switch blades by pulsing nitrogen plasma by K.A. Arushanov; M.N. Drozdov; S.M. Karabanov; I.A. Zeltser; A. Tolstogouzov (pp. 642-647).

► TOF-SIMS depth profiling of reed switch blades before and after ion nitriding was carried out. ► The plasma processing was made directly in sealed reed switches. ► A 350nm-thick oxy-nitride coating in the contacting region was revealed. ► Nitrogen and oxygen diffusion, cathode sputtering and re-deposition of sputtered products, thermal decomposition of nitrides and oxides, sputter-induced surface roughening contribute in the formation of this coating.A TOF.SIMS-5 by ION-TOF operating with pulsed 25keV Bi⁺ for analysis and 2keV Cs⁺ for sputtering was used to study depth compositional changes in near-surface layers of permalloy (iron–nickel) blades after treatment by pulsed nitrogen plasma directly in sealed reed switches. The formation of 350nm-thick oxy-nitride coating in the contacting region of the blades was observed. It was found that the origin of this coating cannot be explained just by nitrogen and oxygen diffusion inside the treated material. Rather, cathode sputtering and re-deposition of sputtered products, thermal decomposition of nitrides and oxides along with sputter-induced surface roughening can also contribute in the formation of the modified layers.

Keywords: Ion-plasma treatment; Nitriding; Reed switch; Sputter depth profiling; Time-of-flight secondary ion mass spectrometry (TOF-SIMS)

Laser-induced front side etching of CaF₂ crystals with KrF excimer laser by Pierre Lorenz; Martin Ehrhardt; Klaus Zimmer (pp. 648-652).

► We studied nanosecond laser-induced front side etching (LIFE) of CaF₂(111) and CaF₂(100). ► The LIFE process at CaF₂ tends to a breaking of the surface along the crystal edges and finally to a rough surface. ► The resulted surface morphology is dependent on the crystal orientation as well as on the laser fluence.The laser-induced front side etching (LIFE) of amorphous materials like fused silica was manifold studied and the LIFE process was sufficient optimized for the fabrication of well-defined etching trenches with a very low surface roughness. The LIFE process is an indirect laser-induced ablation process, the – for the used laser wavelength – transparent substrate was covered by a highly absorbing material and the absorbing process causes a transfer of the laser energy into the substrate and, finally, to an ablation process of the substrate surface.However, the structuring of crystalline materials like CaF₂ is a great challenge for the LIFE process. The properties of CaF₂(111) and CaF₂(001) surfaces etched by KrF excimer laser pulses (pulse duration Δ t_p=25ns, wavelength λ=248nm) were analysed by white light interferometry (WLI) as well as scanning electron microscopy (SEM). The surface morphologies of laser etched CaF₂ surfaces depend on the laser parameters and on the crystal orientation and are frequently characterized by microcracks and flake spallation. The most probable reasons therefore are laser-induced thermal stress or laser-induced shock waves.

Keywords: LIFE; Laser etching; Excimer laser; CaF; ₂

Microstructure and mechanical behavior of pulsed laser surface melted AISI D2 cold work tool steel by N. Yasavol; A. Abdollah-zadeh; M. Ganjali; S.A. Alidokht (pp. 653-662).

► Melted zone contained fine dendrites in the bottom and equiaxed grains on the top. ► Microstructural refinements of PLSM led to microhardness enhancement. ► Higher scanning rate and lower laser energy were more effective to refine the microstructure.D2 cold work tool steel (CWTS) was subjected to pulse laser surface melting (PLSM) at constant frequency of 20Hz Nd: YAG laser with different energies, scanning rate and pulse durations radiated to the surface. Characterizing the PLSM, with optical and field emission scanning electron microscopy, electron backscattered diffraction and surface hardness mapping technique was used to evaluate the microhardness and mechanical behavior of different regions of melting pool. Increasing laser energy and reducing the laser scanning rate results in deeper melt pool formation. Moreover, PLSM has led to entirely dissolution of the carbides and re-solidification of cellular/dendritic structure of a fine scale surrounded by a continuous interdendritic network. This caused an increase in surface microhardness, 2–4 times over that of the base metal.

Keywords: Cold work tool steel; Pulsed Nd-YAG laser; Laser surface melting; Microhardness

The double effects of silver nanoparticles on the PVDF membrane: Surface hydrophilicity and antifouling performance by Jian-Hua Li; Xi-Sheng Shao; Qing Zhou; Mi-Zi Li; Qi-Qing Zhang (pp. 663-670).

► Ag/PVDF-g-PAA composite membrane is firstly prepared. ► Silver nanoparticle provides PVDF membrane a significant improvement of surface hydrophilicity. ► Silver nanoparticle endows PVDF membrane with outstanding antifouling (anti-organic fouling and anti-biofouling) performance.In this study, silver nanoparticles were used to endow poly(vinylidene fluoride) (PVDF) membrane with excellent surface hydrophilicity and outstanding antifouling performance. Silver nanoparticles were successfully immobilized onto PVDF membrane surface under the presence of poly(acrylic acid) (PAA). The double effects of silver nanoparticles on PVDF membrane, i.e., surface hydrophilicity and anti-fouling performance, were systematically investigated. Judging from result of water static contact measurement, silver nanoparticles had provided a significant improvement in PVDF membrane surface hydrophilicity. And the possible explanation on the improvement of PVDF membrane surface hydrophilicity with silver nanoparticles was firstly proposed in this study. Membrane permeation and anti-bacterial tests were carried out to characterize the antifouling performance of PVDF membrane. Flux recovery ratio (FRR) increased about 40% after the presence of silver nanoparticles on the PVDF membrane surface, elucidating the anti-organic fouling performance of PVDF membrane was elevated by silver nanoparticles. Simultaneously, anti-bacterial test confirmed that PVDF membrane showed superior anti-biofouling activity because of silver nanoparticles. The above-mentioned results clarified that silver nanoparticles can endow PVDF membrane with both excellent surface hydrophilicity and outstanding antifouling performance in this study.

Keywords: Poly(vinylidene fluoride) (PVDF) membrane; Silver nanoparticles; Surface hydrophilicity; Antifouling performance; Poly(acrylic acid) (PAA)

Surface alloying method of ultrasonic shot peening on iron surface by Tao Zhang; Dongpo Wang; Ying Wang; Caiyan Deng; Baoming Gong (pp. 671-676).

► A new method of USP to generate alloying layers on the surface of iron has been developed. ► The advantage of this method is simple, flexible and low cost. ► The surface alloy layer consists of Fe-Ni intermetallic compound and solid solution phases.A new method to generate alloying layers on the surface of iron has been developed. Ni powders are introduced to the intense plastic deformed surface of iron by ultrasonic shot peening (USP), followed by annealing at certain temperature for 30min. Thus a surface alloy layer in a plate specimen of commercially pure iron may be produced. XRD, SEM and EDS methods are used to analyze the microstructure, composition distribution and phase constitutions of the alloy layer. Results show that the surface alloy layer with certain thickness on the surface of iron consists of Fe–Ni intermetallic compound and solid solution phases. Corrosion resistance, hardness and roughness have also been discussed.

Keywords: USP; Surface alloying; Anneal treatment; Microstructure; Corrosion resistance

Biotemplated synthesis of high specific surface area copper-doped hollow spherical titania and its photocatalytic research for degradating chlorotetracycline by Dan Bu; Huisheng Zhuang (pp. 677-685).

Display Omitted► The rape pollen grains were used as bio-template to synthesize copper-doped TiO₂ photocatalyst with hollow spherical structure. ► The synthesized processes are simple and gentle. The pollen grains could be easily removed at high temperature. The as-obtained hollow structure is fine. ► Special structure of photocatalyst increases the absorbability and photocatalytic activity. ► The formation mechanism of hollow microsphere synthesized by using pollen as biotemplate had been discussed.Copper-doped titania (Cu/TiO₂) hollow microspheres were fabricated using the rape pollen as biotemplates via an improved sol–gel method and a followed calcinations process. In the fabricated process, a titanium(IV)-isopropoxide-based sol directly coated onto the surface of rape pollen. Subsequently, after calcinations, rape pollen was removed by high temperature and the hollow microsphere structure was retained. The average diameter of as-obtained hollow microspheres is 15–20μm and the thickness of shell is approximately 0.6μm. Knowing from XRD results, the main crystal phase of microspheres is anatase, coupled with rutile. The specific surface area varied between 141.80m²/g and 172.51m²/g. This hollow sphere photocatalysts with high specific surface area exhibited stronger absorption ability and higher photoactivity, stimulated by visible light. The degradation process of chlortetracycline (CTC) solution had been studied. The degradated results indicate that CTC could be effective degradated by fabricated hollow spherical materials. And the intermediate products formed in the photocatalytic process had been identified.

Keywords: Hollow structure; Biotemplate; Copper-doped TiO; ₂; Chlortetracycline (CTC)

Comment on ‘SEM/EDX and XPS Studies of Niobium after Electropolishing’ by T. Hryniewicz, K. Rokosz, H.R. Zschommler Sandim (Appl. Surf. Sci. 263 (2012) 357–361) by Frank Müller; Samuel Grandthyll; Matthias Lessel; Stefan Hüfner (pp. 686-687).

Wetting behaviour of femtosecond laser textured Ti–6Al–4V surfaces by Alexandre Cunha; Ana Paula Serro; Vitor Oliveira; Amélia Almeida; Rui Vilar; Marie-Christine Durrieu (pp. 688-696).

► Wetting behaviour of femtosecond laser textured Ti–6Al–4V surfaces. ► Laser-induced surface textures affect considerably the wettability of the material. ► Femtosecond laser treatment of Ti–6Al–4V surfaces increases their hydrophilicity. ► Surface anisotropy induces an anisotropic wetting.The aim of the present work was to investigate the wetting behaviour of biomedical grade Ti–6Al–4V alloy surfaces textured by a femtosecond laser treatment. The material was treated in ambient atmosphere using an Yb: KYW chirped-pulse-regenerative amplification laser with a wavelength of 1030nm and a pulse duration of 500fs. Four main types of surface textures were obtained depending on the processing parameters and laser treatment method. These textures consist of: (1) nanoscale laser-induced periodic surface structures (LIPSS); (2) nanopillars; (3) a bimodal roughness distribution texture formed of LIPSS overlapping microcolumns; (4) a complex texture formed of LIPSS overlapping microcolumns with a periodic variation of the columns size in the laser scanning direction. The wettability of the surfaces was evaluated by the sessile drop method using distilled-deionized (DD) water and Hank's balanced salt solution (HBSS) as testing liquids. The laser treated surfaces present a hydrophilic behaviour as well as a high affinity for the saline solution, with equilibrium contact angles in the ranges 24.1–76.2° for DD water and 8.4–61.8° for HBSS. The wetting behaviour is anisotropic, reflecting the anisotropy of the surface textures.

Keywords: Wetting behaviour; Femtosecond lasers; Surface texturing; Surface anisotropy; Ti–6Al–4V implants

Chitosan coatings onto polyethylene terephthalate for the development of potential active packaging material by Lidija Fras Zemljič; Tina Tkavc; Alenka Vesel; Olivera Šauperl (pp. 697-703).

Display Omitted► The adsorption/desorption of chitosan onto PET plastic film was studied. ► Chitosan was reversible attached onto PET plastic films. ► Antimicrobial functionalized PET may provide potential active packaging material.In this paper advanced surface treatment of PET plastic film is presented for introduction of antimicrobial properties as a potential application for food (as for example meat) packaging material. Adsorption/desorption of chitosan onto PET plastic film surface was studied using several analytical techniques such as: X-Ray Photoelectron Spectroscopy (XPS), ATR-FTIR spectroscopy and titrations. Kinetic desorption of chitosan from PET surface was analysed by polyelectrolyte titration and spectrophotometric Ninhydrine reaction. Standard antimicrobial test ASTM E2149-01 was performed for functionalised PET materials in order to determine their antimicrobial properties; i. e. to measure the reductions of some of the meat pathogens; such as bacteria Salmonella enterica, Campylobacter spp., Escherichia coli, Listeria monocytogenes and fungi Candida albicans.

Keywords: PET; Chitosan; Titrations; XPS; Antimicrobial properties; Potential active packaging

Tennis core strings of polyamide-6 modified by surface-capped nano-silica by Juan Liu; Hongling Yi; Heng Lin; Baicun Zheng (pp. 704-708).

► The method to produce nylon6/silica composites is melt-extrusion process. ► Using the interactions of silica/polyamide to increase strength and elasticity. ► Epoxy groups decreased the aggregation and improved compatibility of the composites. ► Tennis core string in the study had a higher breaking stress and larger elastic ratio.A new method that modified silica nanoparticles were infused into PA6 is to produce tennis core string through a melt-extrusion process. The idea was to produce a highly strong and elastic tennis core string of PA6, utilizing the interactions between modified silica and polymer. The effects of surface-capped nano-silica on the strength and elongation of tennis core string were studied. It has been observed that with the infusion of silica nanoparticles modified by γ-glycidoxypropyltrimethoxysilane (GPS), the stress at breaking and E-modulus of tennis core string is enhanced by 46.24% and 15.17% comparing with neat PA6 with changeless elongation at breaking at a critical concentration. The source of this improvement has been traced to the produced strong covalent bond and hydrogen bond between epoxy groups and–COOH and–NH₂ in polyamide. Besides, compared with kinds of others strings of previous research results, tennis core string added nano-silica modified by γ-glycidoxypropyltrimethoxysilane (GPS) has a strength at breaking at 352.43MPa exceeding the natural gut string, the polyvinylidene fluoride (PVDF), Monofil string and integrated nylon string by 42.05%, 4.49% and 9.38%, respectively. Meanwhile, tennis core string of polyamide modified by surface-capped nanosilica (PGMNS) has a higher elastic ratio at 0.15 than the other four strings.

Keywords: Tennis core string; Nano-silica; Polyamide-6; Strength; Elasticity

Evaluation of optical parameters and characterization of ultrasonically sprayed MgO films by spectroscopic ellipsometry by S. Kurtaran; I. Akyuz; F. Atay (pp. 709-713).

► MgO films with high resistivity and low refractive index have been obtained by an economical technique. ► Determination of optical parameters by spectroscopic ellipsometry have been performed for the first time. ► MgO thin films with improved characteristics have been obtained after annealing.MgO is a chemically stable buffer layer and a good candidate with its unique optical and structural characteristics such as low refractive index and good lattice matching for the deposition of technologically important materials. In this work, we have produced MgO films by a low cost ultrasonic spray pyrolysis technique and tried to improve their characteristics by thermal annealing. MgO films have been obtained on glass substrates at 325±5°C and annealed at two different temperatures as 500°C and 600°C for 2h. Elemental analyses have been made by energy-dispersive X-ray spectroscopy. Thicknesses, refractive indices and extinction coefficient values have been determined by spectroscopic ellipsometry technique using Cauchy–Urbach model. Band gap values of the films have been calculated using the absorbance spectra and optical method. X-ray diffraction patterns have been used to investigate the structural properties and to calculate lattice parameters. Atomic force microscope images have been taken to see the effect of thermal annealing on surface morphology. Electrical resistivity values of the films have been determined using a four-point probe set-up. As a result, annealing temperature has a strong effect on the mentioned properties and a low cost ultrasonic spray pyrolysis technique allows the production of new and alternative MgO buffer layers for technological applications.

Keywords: Ultrasonic spray pyrolysis; MgO buffer layer; Spectroscopic ellipsometry; XRD; AFM

Adherent diamond film deposited on Cu substrate by carbon transport from nanodiamond buried under Pt interlayer by Xuezhang Liu; Qiuping Wei; Zhiming Yu; Taiming Yang; Hao Zhai (pp. 714-719).

► Adherent polycrystalline diamond films were grown on copper substrate by carbon transport. ► The nucleation density was increased to 10¹¹cm⁻². ► Diamond films were a composite structure of nano-crystalline diamond layer and micro-crystalline diamond layer. ► Diamond nucleation was based by carbon dissolving from UDDs to Pt interlayer and formation of sp³-bonded diamond clusters at the Pt surface.Diamond film deposited on Cu suffered from poor adhesion mainly due to the large mismatch of thermal expansion coefficients and the lack of affinity between carbon and Cu. Enhancing diamond nucleation by carbon transport from buried nanodiamond through a Pt ultrathin interlayer, adherent diamond film was then deposited on Cu substrate without distinctly metallic interlayer. This novel nucleation mechanism increased diamond nucleation density to 10¹¹cm⁻², and developed diamond film with a composite structure of nano-crystalline diamond (NCD) layer and micro-crystalline diamond layer. Diamond film was characterized by the scanning electron microscope (SEM) and Raman spectroscope, respectively. The composition of diamond film/Cu substrate interface was examined by electron probe microanalysis (EPMA). The adhesion of diamond film was evaluated by indentation test. Those results show that a Pt ultrathin interlayer provides stronger chemically bonded interfaces and improve film adhesion.

Keywords: CVD diamond; Cu; Pt interlayer; Carbon transport; Nucleation; Adhesion

Insights into the preference of CH_x( x=1–3) formation from CO hydrogenation on Cu(111) surface by Xuancheng Sun; Riguang Zhang; Baojun Wang (pp. 720-730).

Display Omitted► CO dissociation is less energetically favored than CO hydrogenation on Cu(111). ► CHO formation is more favorable both kinetically and thermodynamically than COH. ► The optimal paths of CH_x( x=1-3) formation have been illustrated. ► CH₂ and CH₃ are the most favored monomer for CO hydrogenation on Cu(111). ► CH₂, CH₃ and CH₃OH formation by CO hydrogenation compete with each other.The mechanisms of CH_x( x=1-3) formation from CO hydrogenation on Cu(111) surface have been systematically investigated using periodic density functional calculations. The activation barriers and reaction energies for all the elementary steps involved in CH_x( x=1-3) formation is presented here. CO hydrogenation and its dissociation have been discussed. Our results show that the CO dissociation route is less energetically favored on Cu(111) surface than CO hydrogenation to form CHO and COH, in which CO mainly goes through hydrogenation to form CHO, meanwhile, the formation of CHO is more favorable both kinetically and thermodynamically than that of COH. Starting from CHO, we further investigate the formation of CH_x( x=1-3), two conditions, without H-assisted and with H-assisted, are considered. As a result, we seek out the optimal paths of CH_x( x=1-3) formation and the corresponding activation barrier of rate-controlled step on Cu(111) surface, moreover, among all CH_x( x=1-3) species, CH₂ and CH₃ are the most favored monomer for CO hydrogenation on Cu(111). In addition, our results show that CH₃OH is also easily formed by CO hydrogenation, and the formations of CH₂, CH₃ and CH₃OH by CO hydrogenation compete with each other on Cu(111) surface.

Keywords: CO; Hydrogenation; CH; _x; CH; ₃; OH; Cu(111); Density functional theory

Microstructure and surface properties of lignocellulosic-based activated carbons by P. González-García; T.A. Centeno; E. Urones-Garrote; D. Ávila-Brande; L.C. Otero-Díaz (pp. 731-737).

Display Omitted► Activated carbons were produced by KOH activation at 700°C . ► The observed nanostructure consists of highly disordered graphene–like layers with sp² bond content ≈ 95%. ► Textural parameters show high surface area (≈ 1000 m²/g) and pore width of 1.3–1.8nm. ► Specific capacitance reaches values as high as 161 F/g.Low cost activated carbons have been produced via chemical activation, by using KOH at 700°C, from the bamboo species Guadua Angustifolia and Bambusa Vulgaris Striata and the residues from shells of the fruits of Castanea Sativa and Juglans Regia as carbon precursors. The scanning electron microscopy micrographs show the conservation of the precursor shape in the case of the Guadua Angustifolia and Bambusa Vulgaris Striata activated carbons. Transmission electron microscopy analyses reveal that these materials consist of carbon platelet–like particles with variable length and thickness, formed by highly disordered graphene–like layers with sp² content ≈ 95% and average mass density of 1.65g/cm³ (25% below standard graphite). Textural parameters indicate a high porosity development with surface areas ranging from 850 to 1100 m²/g and average pore width centered in the supermicropores range (1.3–1.8nm). The electrochemical performance of the activated carbons shows specific capacitance values at low current density (1mA/cm²) as high as 161 F/g in the Juglans Regia activated carbon, as a result of its textural parameters and the presence of pseudocapacitance derived from surface oxygenated acidic groups (mainly quinones and ethers) identified in this activated carbon.

Keywords: Activated carbons; Transmission Electron Microscopy; Pore structure; Electrochemical Double Layer Capacitor

Transparent and conductive indium doped cadmium oxide thin films prepared by pulsed filtered cathodic arc deposition by Yuankun Zhu; Rueben J. Mendelsberg; Jiaqi Zhu; Jiecai Han; André Anders (pp. 738-744).

► High quality CdO:In films were prepared on glass by pulsed filtered cathodic arc. ► 230nm thick films show low resistivity of 7.23×10⁻⁵Ωcm and mobility of 142cm²/Vs. ► In-doping significantly improves the conductivity and extends the transparent range. ► Film crystalline quality is maintained with increasing In concentration. ► The pulsed arc-grown CdO:In show excellent reproducibility of film properties.Indium doped cadmium oxide (CdO:In) films with different In concentrations were prepared on low-cost glass substrates by pulsed filtered cathodic arc deposition (PFCAD). It is shown that polycrystalline CdO:In films with smooth surface and dense structure are obtained. In-doping introduces extra electrons leading to remarkable improvements of electron mobility and conductivity, as well as improvement in the optical transmittance due to the Burstein–Moss effect. CdO:In films on glass substrates with thickness near 230nm show low resistivity of 7.23×10⁻⁵Ωcm, high electron mobility of 142cm²/Vs, and mean transmittance over 80% from 500 to 1250nm (including the glass substrate). These high quality pulsed arc-grown CdO:In films are potentially suitable for high efficiency multi-junction solar cells that harvest a broad range of the solar spectrum.

Keywords: In doped cadmium oxide; Pulsed filtered cathodic arc deposition; Transparent conductors

Annealing effect on the structural and optical properties of Cr/α-Cr₂O₃ monodispersed particles based solar absorbers by S. Khamlich; R. McCrindle; Z.Y. Nuru; N. Cingo; M. Maaza (pp. 745-749).

A cost-effective and environmentally friendly green chemical method, the so-called aqueous chemical growth (ACG) method, was used to deposit chromium/alpha-chromium(III) oxide, Cr/α-Cr₂O₃, monodispersed particles, for solar absorbers applications.Display Omitted► Cr/α-Cr₂O₃ have been deposited by the aqueous chemical growth (ACG) method. ► High temperature annealing affects the optical selectivity of the deposited particles. ► Oxygen diffusion to the interface at high temperature results in the oxidization of the substrate.A cost-effective and environmentally friendly green chemical method, the so-called aqueous chemical growth (ACG) method, was used to deposit chromium/alpha-chromium(III) oxide, Cr/α-Cr₂O₃, monodispersed particles, for solar absorbers applications. The deposited particles were annealed at various temperatures in a hydrogen atmosphere for 2h to study the annealing temperature dependence of the structural, chemical and optical properties of the particles grown on tantalum substrates. The deposited Cr/α-Cr₂O₃ was characterized by X-ray diffraction (XRD), attenuated total reflection (ATR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and diffuse reflectance UV–vis–NIR spectroscopy. The XRD and ATR analysis indicated that by increasing annealing temperature, the particles crystallinity was improved and Ta₂O₅ was formed around 600°C, due to the fast oxygen diffusion from the deposited α-Cr₂O₃ toward the tantalum substrate. The optical measurements show that samples annealed at 400 and 500°C exhibit the targeted high absorbing optical characteristics of “Black chrome”, while those annealed below 400°C and above 500°C show a significant low absorptivity and high emissivity.

Keywords: Solar absorbers; Chromium(III) oxide; Aqueous chemical growth

Influence of the source gas ratio on the hydrogen and deuterium content of a-C:H and a-C:D films: Plasma-enhanced CVD with CH₄/H₂, CH₄/D₂, CD₄/H₂ and CD₄/D₂ by K. Ozeki; D. Sekiba; T. Suzuki; K. Kanda; M. Niibe; K.K. Hirakuri; T. Masuzawa (pp. 750-757).

► We used CH₄/H₂, CH₄/D₂, CD₄/H₂ and CD₄/D₂ in the process gas to deposit a-C:H films using plasma CVD. ► H and D concentration in the film increased with the H₂ and D₂ ratio. ► For all combinations of source gases, the total H and D concentration varied by only 4.0%. ► A correlation between the sp²/(sp²+sp³) ratio and the H₂ or D₂ gas source ratio was not observed. ► The hardness and density of the film decreased when the H₂ or D₂ source gas ratio increased.Amorphous hydrogenated carbon (a-C:H) and amorphous deuterated carbon (a-C:D) films were prepared using plasma-enhanced chemical vapor deposition (PECVD) from CD₄, H₂, CD₄ and D₂ source gases. Fourteen different samples were prepared by changing the source gas ratios of CH₄/H₂, CH₄/D₂, CD₄/H₂, and CD₄/D₂. The concentrations of hydrogen (H) and deuterium (D) relative to carbon (C) in the films were determined by elastic recoil detection analysis (ERDA) and Rutherford backscattering spectroscopy (RBS). The sp²/(sp²+sp³) ratios of the films were analyzed by near-edge X-ray absorption fine structure (NEXAFS) measurements. Hardness and mass density of the films were measured using a nanoindenter and X-ray reflectivity (XRR), respectively. For all combinations of source gas, the H and D concentrations varied by only 4.0at.%. For the CH₄/D₂ source gas, the D concentration in the film increased from 0at.% with the D₂/(CH₄+D₂) source gas combination to 11.2at.% for the 80% D₂/(CH₄+D₂) source gas combination. The increase in D concentration exceeded the increase in total H and D concentration (3.4at.%). For CH₄/D₂ source gas, the H concentration decreased as the D concentration increased. For the CD₄/H₂ source gas, we observed the opposite tendency. Additionally, an isotope effect between the a-C:H films and the a-C:D films was observed, with preferential incorporation of H over D. From the NEXAFS measurements, the sp²/(sp²+sp³) ratios in all of the samples were between 38.8% and 40.8%. A correlation between the sp²/(sp²+sp³) ratio and the H₂ or D₂ gas source ratio was not observed. The hardness and density of the films decreased when the H₂ or D₂ source gas ratio increased. Even though the H concentration in the a-C:H films was higher than the D concentration in the a-C:D films, the a-C:D films had lower hardness and mass density values. These findings suggest that information concerning the voids, nanostructures, sp²/sp³ ratios and H concentrations of hydrogenated amorphous carbon films is crucial for evaluation of their mechanical properties.

Keywords: Amorphous hydrogenated carbon; Deuterium; Hydrogen; ERDA; RBS; NEXAFS; Hardness

Mechanical characterization of aluminum doped zinc oxide (Al:ZnO) nanorods prepared by sol–gel method by A. Kumar; N. Huang; T. Staedler; C. Sun; X. Jiang (pp. 758-763).

► Aluminum doped ZnO nanorods on the lime-glass substrates prepared by sol–gel method. ► Single crystal along the [002] direction without any dislocation ZnO nanorods. ► Surface and bucking instabilities of ZnO nanorods. ► Uniaxial compression tests with different indenters and comparison of their results.The surface and bucking instabilities of vertical well-aligned aluminum doped ZnO nanorods on the lime-glass substrates prepared using the sol–gel method are characterized by nanoindentation tests. Comprehensive structural analysis by X-ray diffraction and scanning electron microscopy reveal that the ZnO nanorods are grown as a single crystal along the [002] direction without any dislocation. Uniaxial compression tests of individual nanorods with the Berkovich and a conical indenter and of group of nanorods with flat punch indenter have been carried out. Using the Euler buckling model, the elastic moduli of ZnO nanorods using these three different indenters are within the range of 175–256GPa. We discuss the relative merits of these two approaches for the determination of the elastic properties of ZnO nanorods, particularly considering the difference and difficulties of each approach. The ZnO nanorods prepared by the sol–gel method are mechanically strong and may assist the development of the applications of one dimensional nanorods.

Keywords: Nanorod; Nanoindentation; Mechanical properties; Sol–gel

Electrochemical investigation of copper passivation kinetics and its application to low-pressure CMP modeling by Jing Li; Yuhong Liu; Tongqing Wang; Xinchun Lu; Jianbin Luo (pp. 764-770).

► The copper passivation kinetics is studied by the chronoamperometry technique. ► A model based on the passivation kinetics is proposed for low-pressure CMP. ► The mechanical effect dominates the material removal at pH 4. ► It is a chemical dominant process at pH 10 during low-pressure CMP.During the process of chemical mechanical planarization (CMP) of copper interconnection in ultra large scale integration (ULSI), copper passivation plays a critical role in material removal. The kinetics of copper passivation in glycine solutions containing BTA was studied by the chronoamperometry technique. The results showed that the current density transients followed with a double-exponential decay, including both non-faradaic double layer charging and faradaic reaction effects. Furthermore, a model based on the passivation kinetics was proposed for low-pressure CMP. Combining the model and the experimental results, the material removal mechanism was analyzed. The mechanical effect dominated the material removal at pH 4, while it was a chemical dominant process at pH 10.

Keywords: Low -pressure CMP; Copper passivation kinetics; Model

Phase- and shape-controlled hydrothermal synthesis of CdS nanoparticles, and oriented attachment growth of its hierarchical architectures by Yali Cao; Pengfei Hu; Dianzeng Jia (pp. 771-777).

CdS nanostructures with controllable phases, sizes, and morphologies were synthesized by hydrothermal method. Oriented attachment growth mode was suggested for the formation of CdS superstructures. The CdS superstructures exhibited the enhanced visible emission with a peak in the green regions.Display Omitted► Novel CdS nanocrystals with well-defined leaf- and flower-like shape were achieved. ► Oriented attachment growth mode was suggested for the formation of CdS superstructures. ► The CdS superstructures exhibited the enhanced visible emission.Hydrothermal strategies were successfully used to control the phases and morphologies of CdS nanocrystals. In the absence of an external direction-controlling process, the hexagonal and cubic phase well-defined leaf- and flower-like CdS nanocrystals were controlled obtained via adjusting the reaction duration or the concentration of surfactant. Oriented attachment growth modes were suggested for the formation of CdS superstructures, which was clarified through the tracing of temporal evolution of CdS nanoparticles. The CdS superstructures were structured by primary building nanoparticles, and held excellent visible emission with a peak in the green regions. This strategy is very helpful for studying the phase and morphology controlled fabrication of sulfides nanocrystals.

Keywords: CdS; Nanostructures; Hydrothermal synthesis; Photoluminescence

Solvothermal synthesis of carbon coated N-doped TiO₂ nanostructures with enhanced visible light catalytic activity by Xue-Min Yan; Jialing Kang; Lin Gao; Lin Xiong; Ping Mei (pp. 778-783).

► Chitosan was used as carbon and nitrogen resource to modify TiO₂ nanostructure. ► Nanocomposites with mesostructure were obtained by one-step solvothermal method. ► Carbon species were modified on the surface of TiO₂. ► Nitrogen was doped into the anatase titania lattice. ► CTS-TiO₂ nanocomposites show superior visible light photocatalytic activity.Visible light-active carbon coated N-doped TiO₂ nanostructures(CTS-TiO₂) were prepared by a facile one-step solvothermal method with chitosan as carbon and nitrogen resource at 180°C. The as-prepared samples were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), N₂ adsorption–desorption analysis, X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy. The CTS-TiO₂ nanocomposites possess anatase phase of nanocrystalline structure with average particle size of about 5–7nm. A wormhole mesostructure can be observed in the CTS-TiO₂ nanocomposites due to the constituent agglomerated of nanoparticles. It has been evidenced that the nitrogen was doped into the anatase titania lattice and the carbon species were modified on the surface of TiO₂. The photocatalytic activities of the as-prepared photocatalysts were measured by the degradation of methylene blue (MB) under visible light irradiation at λ≥400nm. The results show that CTS-TiO₂ nanostructures display a higher visible light photocatalytic activity than pure TiO₂, commercial P25 and C-coated TiO₂ (C-TiO₂) photocatalysts. The higher photocatalytic activity could be attributed to the band-gap narrowed by N-doping and the accelerated separation of the photo-generated electrons and holes by carbon modification.

Keywords: Solvothermal; Carbon coated; Nitrogen doping; Photocatalytic activity; Visible light

Formation of superhydrophobic soda-lime glass surface using femtosecond laser pulses by Md. Shamim Ahsan; Fadia Dewanda; Man Seop Lee; Hitoshi Sekita; Tetsumi Sumiyoshi (pp. 784-789).

Display Omitted► We formed superhydrophobic soda-lime glass surface by femtosecond laser pulses. ► Periodic microstructures are printed on the glass surface for superhydrophobicity. ► The contact angle of water droplet on the microstructured glass surface is 155°. ► The transparency of superhydrophobic glass is higher than 77% in visible spectrum. ► We explain the formation mechanism of superhydrophobic soda-lime glass surface.This paper demonstrates the fabrication of superhydrophobic soda-lime glass surface by engineering periodic microgratings with self-formed periodic micro-ripples inside the microgratings using a single beam femtosecond laser. The wetting property of the microstructured surface is improved from hydrophobic to superhydrophobic, presenting a water droplet contact angle ranges from 152° to 155°. The microstructured glass surface shows excellent transparency, which is higher than 77% in the visible spectrum. We strongly believe that our proposed technology can achieve superhydrophobic glass surfaces over a large area for applications in diverse fields.

Keywords: Femtosecond laser; Superhydrophobic soda-lime glass; Microgratings; Self-formed micro-ripples

Iron migration from the anode surface in alumina electrolysis by Elena N. Zhuravleva; Tatiana N. Drozdova; Svetlana V. Ponomareva; Sergei D. Kirik (pp. 790-795).

Display Omitted► Corrosion destruction of two-component iron-based alloys in high-temperature aluminum electrolysis in the cryolite alumina melt has been studied. ► It was found that at the first stage oxidative polarization of iron atoms on the anode surface into Fe²⁺ takes place. ► Fe²⁺ interacts with cryolite melt producing FeF₂. ► FeF₂ gives oxides FeAl₂O₄, Fe₃O₄, Fe₂O₃. ► The participation of oxygen in the corrosion has not been observed.Corrosion destruction of two-component iron-based alloys used as an anode in high-temperature alumina electrolysis in the melt of NaF/KF/AlF₃ electrolyte has been considered. Ni, Si, Cu, Cr, Mn, Al, Ti in the amount of up to 10% have been tested as the dopants to an anode alloys. The composition of the corrosion products has been studied using X-ray diffraction, scanning electron microscopy and electron microprobe analysis. It has been established that the anode corrosion is induced by a surface electrochemical polarization and iron atom oxidation. Iron ions come into an exchange interaction with the fluoride components of the melted electrolyte, producing FeF₂. The last interacts with oxyfluoride species transforming into the oxide forms: FeAl₂O₄, Fe₃O₄, Fe₂O₃. Due to the low solubility, the iron oxides are accumulated in the near-electrode sheath. The only small part of iron from anode migrates to cathode that makes an production of high purity aluminum of a real task. The alloy dopants are also subjected to corrosion in accordance with electromotive series resulting corrosion tunnels on the anode surface. The oxides are final compounds which collect in the same area. The corrosion products form an anode shell which is electronic conductor at electrolysis temperature. The electrolysis of alumina occurs beyond the corrosion shell. The rate limiting step in the corrosion is the electrolyte penetration through corrosion shell to the anode surface. The participation of the released oxygen in the corrosion has not been observed.

Keywords: Corrosion mechanism; Alumina electrolysis; Metallic inert anodes in aluminum production

Enhancement of stability of N-doped TiO₂ photocatalysts with Ag loading by Yuanpeng Gao; Pengfei Fang; Feitai Chen; Yang Liu; Zhi Liu; Dahai Wang; Yiqun Dai (pp. 796-801).

► An effective and alternative approach is proposed to stabilize the N dopants for TiO₂. ► Introduction of Ag restrains the escape of N dopants during the hydrothermal process. ► The escape rate of N dopants decreased with the increase of Ag loading amount. ► Ag nanoparticles with appropriate dosage acted as electron traps. ► The photocatalytic activity can be adjusted by altering the Ag content.Various contents of Ag nanoparticles were successfully introduced into the N-doped TiO₂ photocatalysts via a hydrothermal procedure in the silver-ammonia solutions with different Ag concentrations. Effects of Ag loading on the structure and properties of N-doped TiO₂ photocatalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, fluorescence spectroscopy (FL), UV–vis spectroscopy, X-ray photoelectron spectroscopy (XPS), and N₂ physical adsorption analysis. The relationship between the stability of N dopants in TiO₂ lattice and the Ag loading content was investigated for the first time. The results confirm that Ag nanoparticles loading on TiO₂ surfaces significantly restrain the escape of the N dopants from the oxide during the hydrothermal process, and the escape rate of N dopants decreased gradually with the increase of Ag loading amount. The dependence of photocatalytic activity on Ag content was also investigated through degradation of rhodamine B (RhB) under visible light irradiation. It was found that the photocatalytic activity increases gradually with increasing Ag content first, and then decreases after exceeding the optimal Ag content. Therefore, the photocatalytic activity of Ag/N co-modified TiO₂ photocatalysts can be adjusted by the Ag content.

Keywords: N-doped TiO; ₂; Ag loading; Hydrothermal treatment; Stability; Photocatalytic activity

Electrochemical tuned scattering of gold nanostructure by Yu Huang; Liangping Xia; Zheng Yang; Yuan Liu; Wanyi Xie; Hua Zhang (pp. 802-809).

► We investigated the scattering of 16nm thickness gold film and 16nm height gold nanoprism under potential control between 200mV and −200mV. ► The presence of adsorption ion which increased the double layer capacitance had been observed from the change in scattering. ► An exponential function was used to explain the differential scattering of gold nanostructure under the application of potential cyclic voltammetry. ► Time constants deduced from the exponential function had a relationship with the scan rates of potential cyclic voltammetry.The ultrathin gold film and gold nanoprism immobilized on ITO electrodes displayed strong perturbed plasmonic scattering as the result of potential linear sweep and step applications. Although nanoscale surface structure strongly determines the potential-dependent plasmonic response of gold nanostructure, the universality of exponential fit for the differential scattering induced by the potential linear sweep indicates the same mechanism could be widely used to explain the effect of potential on the gold nanostructure. The larger scattering changed by the anodic potential step than cathodic counterpart is attributed to increased double layer capacitance due to the presence of adsorptive ion. The presence of potential controlled scattering indicates the tunability of localized surface plasmon resonance of gold nanostructure.

Keywords: Gold nanostructure; Potential sweep transient; Potential step transient; Adsorptive ion

Influence of valence state, radius of ion and molar ratio of directing salt on WO₃·0.33H₂O crystal morphology by Xiaoyu He; Chenguo Hu; Yi Xi; Qianning Yi; Hao Hua (pp. 810-816).

The effects of the valence state (Na⁺, Ca2⁺), radius of ions (Ca²⁺2+2+), molar ratio of W to Ca, and reaction time on the crystal structure and morphology of the products have been investigated.Display Omitted► Different morphology of WO₃·0.33H₂O was achieved using capping agent by a hydrothermal condition. ► Effects of valence state, radius of ions, molar ratio on the crystal morphology were investigated. ► Optimal experimental condition to grow the well defined three-dimensional framework was obtained.WO₃·0.33H₂O networks were prepared by using structure-directing agent under a hydrothermal condition. The influences of the valence state (Na⁺, Ca²⁺), radius of ions (Ca²⁺2+2+), molar ratio of W to Ca, and reaction time on the crystal structure and morphology of the products have been investigated systematically. It was found that higher ion valence state (2+), smaller ion radius (Ca²⁺), 1:1 molar ratio of W to Ca and 15h reaction time at 180°C were the optimal experimental condition for the growth of well-defined three- dimensional networks. The proposed growth mechanism of the nanostructures can provide important information for structure design and morphology-controlled synthesis of WO₃·0.33H₂O and other oxides.

Keywords: Tungsten oxide; Network; Hydrothermal synthesis; Growth mechanism

Photoemission study of cerium silicate model systems by Tomáš Skála; Vladimír Matolín (pp. 817-822).

Display Omitted► We studied the interaction of ceria with silicon by photoelectron spectroscopy. ► Two model systems were silicon deposited on ceria and ceria deposited on silicon. ► Cerium silicate was formed in both cases.Interaction of silicon with cerium oxide was studied by photoelectron spectroscopy using two model systems CeO_x/Si(111) and Si/CeO₂(111)/Cu(111) which can be used for fundamental studies in the field of microelectronics and heterogeneous catalysis. The interaction was found to be strong and lead to a formation of cerium silicate films of the proposed stoichiometry Ce_4.67Si₃O₁₃. Their maximum thickness was limited by diffusion of silicon. Beside silicate other compounds were growing on the surface – SiO₂, Si₂O, Si, and CeO₂. The assignment of the formed species is based on the interpretation of photoemission spectra involving the measurements of various reference O/Si and SiO/Cu systems.

Keywords: PACS; 71.20.Eh; 71.20.Nr; 79.60.Dp; 33.60.FyCerium oxide; Silicon; Cerium silicate; Thin layer growth; Photoelectron spectroscopy

Effect of regular surface textures generated by laser on tribological behavior of Si₃N₄/TiC ceramic by Youqiang Xing; Jianxin Deng; Ze Wu; Hongwei Cheng (pp. 823-832).

► Two kinds of micro-grooved textures were fabricated on Si₃N₄/TiC ceramic. ► Tribological properties of the samples were studied in different conditions. ► Wavy grooves show the most effective in reducing the friction coefficient. ► The major wear mechanisms of samples are adhesions.Two kinds of regular micro-grooved textures with different geometric characteristics were fabricated on the surfaces of Si₃N₄/TiC ceramics by Nd:YAG laser; friction and wear tests were carried out to investigate the tribological properties of these textured ceramics in unlubricated and MoS₂ lubricated conditions. The wear surfaces of the textured ceramics and the balls were examined by SEM and the possible friction reduction and wear resistant mechanisms were discussed. The results show that the friction coefficient of the textured ceramics was reduced compared with the smooth ceramics among all the experiments, the wavy grooves are the most effective in the friction-reduction among the patterns investigated, and the wear life of textured ceramics can be increased in MoS₂ lubricated condition. Furthermore, it is observed that the textured ceramics produce more abrasive wear on the ball specimens in unlubricated friction, while it reduces the wear of balls in MoS₂ lubricated condition. The main effect mechanism of textures is to capture debris and reduces the contact area of couples in unlubricated condition, and increase lubricant supply by reservoir creation and form the continued lubricating film on the surfaces of spacing between the textures in MoS₂ solid lubricated condition.

Keywords: Textures; Friction; Wear; MoS; ₂; Si; ₃; N; ₄; /TiC ceramic

Thermal processing of strained silicon-on-insulator for atomically precise silicon device fabrication by W.C.T. Lee; N. Bishop; D.L. Thompson; K. Xue; G. Scappucci; J.G. Cederberg; J.K. Gray; S.M. Han; G.K. Celler; M.S. Carroll; M.Y. Simmons (pp. 833-838).

► Strained silicon-on-insulator (sSOI) samples were flash-annealed at high temperature under ultra-high vacuum conditions. ► The extend of surface strain relaxation depends on the annealing temperature with no strain relaxation observed below 1020°C. ► A 2×1 reconstructed surface with low defect density can be achieved. ► The annealed sSOI surface shows enhanced step undulations due to the unique energetics caused by surface strain.We investigate the ability to reconstruct strained silicon-on-insulator (sSOI) substrates in ultra-high vacuum for use in atomic scale device fabrication. Characterisation of the starting sSOI substrate using μRaman shows an average tensile strain of 0.8%, with clear strain modulation in a crosshatch pattern across the surface. The surfaces were heated in ultra-high vacuum from temperatures of 900°C to 1100°C and subsequently imaged using scanning tunnelling microscopy (STM). The initial strain modulation on the surface is observed to promote silicon migration and the formation of crosshatched surface features whose height and pitch increases with increasing annealing temperature. STM images reveal alternating narrow straight S_A steps and triangular wavy S_B steps attributed to the spontaneous faceting of S_B and preferential adatom attachment on S_B under biaxial tensile strain. Raman spectroscopy shows that despite these high temperature anneals no strain relaxation of the substrate is observed up to temperatures of 1020°C. Above 1100°C, strain relaxation is evident but is confined to the surface.

Keywords: Silicon-on-insulator; Strained silicon; STM fabrication; Micro-Raman; Step formation; Ultra-high vacuum

Studies on the electrodeposition of tin from acidic chloride–gluconate solutions by Ewa Rudnik; Grzegorz Włoch (pp. 839-849).

► Electrodeposition of tin from acidic chloride–gluconate baths is described. ► pH-dependent equilibrium distribution of tin(II) species in the solutions was calculated. ► Effect of Sn(II) concentration on the electrochemical behavior of the system was found. ► Characterization of deposits was presented.Electrodeposition of tin from acidic chloride–gluconate baths was investigated. Equilibrium distribution of tin(II) species showed domination of Sn(II)–gluconate complexes, but for Sn²⁺ concentrations 50mM or higher increased percentage of Sn(II)–chloride complexes was found. Cyclic voltammetry, anodic stripping analysis and potentiostatic measurements indicated that rate of the cathodic process is determined by the release of metal cations from gluconate complexes in diluted bath (5mM), but for more concentrated solutions reduction of Sn(II) ions run under diffusion control. Studies of anodic response showed that it depends on the Sn(II)/Glu ratio in the bath and deposition potential due to development of different planes of metal crystal. Average effective diffusion coefficients of metal species were determined. Morphology and structure tin deposits were also presented.

Keywords: Tin; Electrodeposition; Complexes; Nucleation; Speciation

Tribological and cutting behavior of silicon nitride tools coated with monolayer- and multilayer-microcrystalline HFCVD diamond films by Naichao Chen; Bin Shen; Guodong Yang; Fanghong Sun (pp. 850-859).

► Multilayer-MCD film shows lower friction coefficient compared monolayer-MCD film. ► Multilayer-MCD film is similar in friction coefficient to monolayer-SMCD film. ► Multilayer-MCD film presents the higher wear resistance than monolayer-SMCD film. ► Multilayer-MCD diamond insert presents the perfect behavior regarding tool wear.Monolayer-micrometric (MN-MCD), monolayer-submicrometric (MN-SMCD) and multilayer-micrometric (MT-MCD) diamond films are grown on silicon nitride substrates by hot filament chemical vapor deposition (HFCVD) technique. The as-deposited diamond films are characterized with scanning electron microscope (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectrometer (EDS), Raman spectrum and 3D surface topography. Tribological properties are assessed by the sliding tests using a reciprocal motion ball-on-flat (BOF) configuration. The friction coefficients are measured as 0.126 for the MN-MCD films, 0.076 for the MN-SMCD films and 0.071 for the MT-MCD films during dry sliding against silicon nitride counterface. The different carbon content of the films may result in the visible diminution of friction coefficient for the MT-MCD films relative to the MN-MCD films. The results show that the MN-MCD and MT-MCD films present the much higher wear resistance than the MN-SMCD films. Meanwhile, the cutting performances of as-deposited diamond films are evaluated by machining aluminum–silicon alloy material. The experimental results show that the MT-MCD insert presents the best behavior regarding the tool wear.

Keywords: Diamond; CVD coating; Friction; Wear; Cutting tools; Silicon nitride

Antiferromagnetic–paramagnetic state transition of NiO synthesized by pulsed laser deposition by S.S. Nkosi; B. Yalisi; D.E. Motaung; J. Keartland; E. Sideras-Haddad; A. Forbes; B.W. Mwakikunga (pp. 860-864).

► Thin films of NiO were prepared on Al substrate at different conditions. ► Antiferromagnetic to paramagnetic state transition were observed. ► The effect of substrate temperature on magnetic properties was studied. ► MWCNTs were incorporated on NiO to study their effect in the NiO magnetism.Thin films of nickel oxide (NiO) were deposited on Al substrates at different substrate temperatures using pulsed laser deposition (PLD). Microwave power absorption measurements at 9.4GHz (X-band) were carried out on these PLD grown films. Multi-walled carbon nano-tubes (MWCNTs) were incorporated with NiO films and were found not to have any effect on the NiO magnetism at room temperature substrate deposition. The MWCNTs and NiO particles have been found to vary in size from 73 to 44nm and 20nm respectively from Raman spectroscopy study. These particle sizes are known be affected by substrate temperature during the deposition. Electron spin resonance (ESR) results demonstrated a strange antiferromagnetic to paramagnetic transition at a room temperature. This magnetic transition was attributed to the substrate temperature variations during the films growth. In addition, the angular dependence measurements were also carried out and were seen to enhance this magnetic transition from NiO films. Normally, such magnetic transitions are observed in situ with temperature variations in the ESR system. Both Raman and ESR measurements suggest the absence of detectable Magnons which act as disturbances to magnetism or electron spins.

Keywords: Antiferromagnetic; Paramagnetic; NiO; Pulsed laser deposition

Water spray assisted ultrashort laser pulse ablation by M. Silvennoinen; J.J.J. Kaakkunen; K. Paivasaari; P. Vahimaa (pp. 865-869).

► We show the novel method to use multibeam processing with ultrashort pulses efficiently. ► Sprayed thin water layer on ablation zone enhances ablation rate and quality. ► In some cases this method also enables ablation of the deeper and straighter holes compared to ones made without the water layer. ► Method also makes possible to directly write features without the self-organizing structures.We have studied femtosecond ablation under sprayed thin water film and its influence and benefits compared with ablation in the air atmosphere. These have been studied in case of the hole and the groove ablation using IR femtosecond laser. Water enhances the ablation rate and in some situations it makes possible to ablate the holes with a higher aspect ratio. While ablating the grooves, the water spray allows using the high fluences without the generation of the self-organized structures.

Keywords: Laser ablation; Ultra short pulses; Diffractive optical element

Investigation of structural, optical and electronic properties in Al–Sn co-doped ZnO thin films by Zhanchang Pan; Xinlong Tian; Shoukun Wu; Xia Yu; Zhuliang Li; Jianfeng Deng; Chumin Xiao; Guanghui Hu; Zhigang Wei (pp. 870-877).

► Al and Sn co-doped ZnO thin films were synthesized by sol–gel method. ► The effects of different Sn doping concentrations were investigated. ► The co-doped nanocrystals exhibit good crystal quality. ► The origin of the photoluminescence emissions was discussed. ► The films showed high transmittance and low resistivity.Al–Sn co-doped ZnO (ATZO) nanocrystals were successfully synthesized onto glass substrates by the sol–gel processing. The structure and morphology of the films are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The results indicated that co-doped ZnO films showed a preferred orientation toward the c-axis and the full width at half maximum (FWHM) of the (002) plane increased first and then decreased, reaching a minimum of about 0.213 with Sn concentration of 2%. The effects of various Sn concentrations on electrical and optical properties were also investigated by 4-point probe device and ultraviolet–visible (UV–vis) spectroscopy, respectively. The X-ray photoelectron spectroscopy (XPS) study showed SnO and AlO bonding in the synthesized co-doped ZnO thin films, which confirmed the substitution of Zn²⁺ by Sn and Al ions. Room temperature photoluminescence (PL) was observed for pure and co-doped ZnO thin films and the origin of these emissions was discussed.

Keywords: Al–Sn co-doped ZnO; XPS; Optical bandgap; Sol–gel method

In vitro corrosion behavior and cellular response of thermally oxidized Zr–3Sn alloy by F.Y. Zhou; B.L. Wang; K.J. Qiu; H.F. Li; L. Li; Y.F. Zheng; Y. Han (pp. 878-888).

► A main monoclinic ZrO₂ layer formed on ZrSn alloy after thermal oxidation. ► Corrosion resistance of ZrSn alloy was improved with thermal oxidation. ► The oxide layer inhibited the release of the ions into the mediums. ► Oxidized ZrSn alloy exhibited an excellent in vitro biocompatibility.In this study, ZrSn alloy was thermally oxidized at 600°C for 3h and its morphological and structural characteristics, corrosion behavior, ion release and in vitro cytocompatibility were studied to evaluate the feasibility of applying it as dental implant. After oxidation, a dense black oxide layer formed on ZrSn alloy surface, which consisted of predominant monoclinic zirconia and a few non-stoichiometric oxides. The scratching and water contact angle test results demonstrated that the oxide layer exhibited good adhesion strength and similar hydrophilicity to zirconia. The oxidized ZrSn alloy showed higher corrosion resistance, as indicated by far lower corrosion current density and passive current density compared to pure Ti and untreated ZrSn alloy in artificial saliva with and without H₂O₂. The amount of ions released from the oxidized ZrSn alloy was much lower than that dissolved from pure Ti in simulated corrosive oral mediums. Moreover, the oxidized ZrSn alloy did not present any significant toxic effect to both osteoblast-like cells and fibroblast cells, and osteoblast-like cells could adhere well onto the surface and exhibited a good proliferative pattern. The combination of improved surface properties, superior corrosion resistance and good biocompatibility made the oxidized ZrSn alloy promising for oral implantology application.

Keywords: ZrSn alloy; Thermal oxidation; Corrosion behavior; Ion release; Cytotoxicity

Different K⁺–Na⁺ inter-diffusion kinetics between the air side and tin side of an ion-exchanged float aluminosilicate glass by Liangbao Jiang; Xintao Guo; Xiaoyu Li; Lei Li; Guanli Zhang; Yue Yan (pp. 889-894).

► The difference between the diffusion characteristics of K⁺–Na⁺ ions in float glass on the air and tin sides was first demonstrated. ► The diffusion coefficient is more sensitive to temperature and time on the tin than on the air sides. ► The activation energy on the tin side is about three times larger than that on the air side.The difference between the inter-diffusion kinetics of K⁺–Na⁺ in the air and tin sides of an ion-exchanged float aluminosilicate glass was investigated as a function of the exchange temperature and time. The potassium concentration profiles of the ion-exchanged glass surface were experimentally measured by electron microprobe analysis, and the diffusion coefficient was calculated by the Boltzmann-Montano approach. On the tin side of the ion-exchanged glass, the diffusion of K⁺–Na⁺ ions is hindered by tin. The diffusion coefficient is also more sensitive to temperature and time on the tin than on the air sides. The results would be useful in guiding the strengthening process of float glass by one step ion-exchange or two step ion-exchange to obtain engineered stress profile (ESP) glasses.

Keywords: Inter-diffusion kinetics; Air side; Tin sides; Ion-exchange; Aluminosilicate glass

Some higher N-substituted 1,3-thiazolidine-2,4-diones and 5,5-diphenylhydantoins, their synthesis and corrosion preventive properties in mineral oil medium by Serkan Öztürk; Ayhan Yıldırım; Mehmet Çetin (pp. 895-903).

► N-substituted 5,5-diphenylhydantoins and 1,3-thiazolidine-2,4-diones were prepared. ► All synthesized compounds showed good inhibition effect in oil–water medium. ► The test results were supported with water contact angle measurements and with SEM. ► Inhibition effect of compounds were evidenced by the optical profilometer photos.Some five membered heterocyclic compounds were synthesized by the reaction of 2,4-thiazolidinedione or 5,5-diphenylhydantoin potassium salts with 2-chloro-N-alkylacetamides and alkyl-2-chloroacetates. The structure confirmations of the synthesized compounds were performed by FT-IR,¹H NMR,¹³C NMR spectra. The inhibitory effectiveness of the compounds were evaluated against the corrosion of steel strip immersed in water containing paraffin based mineral oil medium in accordance to standard test method. Surface characterization studies of the metal coupons used were performed by SEM analysis and also by the contact angle measurements using the Sessile–Drop method. In addition the 3D image of the metal surface was obtained using optical profilometer. The test results and surface characterization studies showed that all synthesized compounds are excellent corrosion inhibitors in such a water in oil emulsion system.

Keywords: Carbon steel; Corrosion inhibitor; Heterocycles; Oil–water medium; Surface studies, Scanning electron microscopy

Synthesis of photoactive AgCl/SBA-15 by conversion of silver nanoparticles into stable AgCl nanoparticles by M. Zienkiewicz-Strzałka; S. Pikus (pp. 904-911).

Display Omitted► A new material AgCl/SBA-15 was synthesized and characterized. ► New simple and effective approach of preparation was proposed. ► AgCl/SBA-15 material was tested as an active agent during photodegradation of phenol and its photoactivity was confirmed. ► The photoactive properties depend on AgCl nanoparticles present in the composite.In this work the results of synthesis the ordered mesoporous silica (SBA-15) in the presence of stable silver nanoparticles were presented. It has been proven that the proposed method leads to the synthesis of SBA-15 nanocomposite containing silver chloride nanoparticles, formed by the transformation of silver nanoparticles in the acidic conditions. Proposed one-pot procedure is simple and the one requirement is to prepare a stable solution of silver nanoparticles. In this work, silver nanoparticles were obtained during chemical reduction of [Ag(NH₃)₂]⁺ ions by formaldehyde. Silver nanoparticles solution can be used as a silver chloride source due to the application of the same polymer as a stabilizer of nanocrystals and structure directing agent of SBA-15.The final AgCl/SBA-15 materials show excellent structural ordering characteristic for this type of materials confirmed by diffraction measurements in range of small angles 2 θ, transmission electron microscopy (TEM) and nitrogen adsorption/desorption measurements. AgCl nanoparticles were identified by diffraction measurements as chlorargyrite phase. The presence of silver nanoparticles in initial solution and their absence after synthesis were confirmed by UV–vis measurements. The photoactivity of obtained AgCl/SBA-15 composite was tested in reaction of organic impurities photodegradation.

Keywords: Mesoporous silica; SBA-15; Silver chloride; Photochemistry; Surface plasmon; UV–vis

Nonmetal species in the carbon modified TiO₂ and its visible light photocatalytic activity by Yanfen Shi; Feng Chen; Jinlong Zhang (pp. 912-918).

Display Omitted► A carbon modified TiO₂ with high visible photocatalytic activity was prepared. ► Visible light activity of CT is largely due to the surface deposited organics. ► Visible photocatalytic activity of CT was significantly reduced with NaOH elution. ► Reactivity of CT was recovered by re-assembling the eluted organics onto the TiO₂.A carbon modified TiO₂ (CT) was synthesized by hydrolyzing titanium tetrachloride with diethylamine and calcination at 400°C. CT was then handled with a NaOH aqueous solution elution and a subsequent re-assembling treatment. X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption–desorption analysis, X-ray photoelectron spectroscopy (XPS), thermogravimetric and differential thermal analysis (TG-DTA), chemical oxygen demand (COD) and UV-vis diffuse reflectance spectroscopy (DRS) were then used to assess the changes of CT during the whole process. It is revealed that carbon in the CT should mostly be presented as surface deposited organic matters but not likely doped into the TiO₂ lattice. CT exhibits obvious visible absorption and high photocatalytic activity for the degradation of 2,4-dichlorophenol (DCP) under visible light irradiation. Meanwhile, CT photocatalyst possesses excellent stability and reusability. NaOH solution elution washes off a large amount of surface deposited organics and worsens the visible absorbance and photocatalytic activity of CT, which can be well recovered by the re-assembling treatment. The re-assembled photocatalyst, CT_SL, exhibits exhibits a very similar photocataytic activity with CT for degradation of DCP under the visible light irradiation, but is much higher than that of CT_S.

Keywords: Titanium dioxide; Nonmetal species; Visible photocatalytic activity; Elution; Re-assembling

Surface and porous characterisation of activated carbons made from a novel biomass precursor, the esparto grass by J.M. Valente Nabais; C. Laginhas; M.M.L. Ribeiro Carrott; P.J.M. Carrott; J.E. Crespo Amorós; A.V. Nadal Gisbert (pp. 919-924).

► We have used a novel precursor for the production of microporous activated carbons. ► Materials with basic properties and high surface areas were produced. ► Esparto grass has an interesting potential for the production of activated carbons using carbon dioxide as activation method. ► SEM images have shown the presence of nanofibers on the internal structure of the carbons.In the work now reported the production of activated carbons from a novel precursor, esparto grass, by activation with carbon dioxide is presented. The results show that the materials produced have interesting properties, namely BET apparent surface area and pore volume up to 1122m²g⁻¹ and 0.46cm³g⁻¹, respectively. The activated carbons have basic characteristics with point of zero charge between 9.25 and 10.27 and show a very fascinating structure, as shown by the SEM images.

Keywords: Activated carbon; Esparto grass; Biomass conversion; Thermal treatment; Nanofibers

Effect of partial UV illumination on a mixture of water and a methylene blue solution in a microchannel coated with TiO₂ by Munetoshi Sakai; Yasushi Morii; Daito Kobayashi; Tsutomu Furuta; Toshihiro Isobe; Sachiko Matsushita; Akira Fujishima; Akira Nakajima (pp. 925-928).

Effects of UV illumination on a mixture of water and a methylene blue (MB) solution in a TiO₂-coated microchannel were investigated by changing the illuminated section. The TiO₂ coating possessed photocatalytic activity. The mixing length of the liquids increased during UV illumination of an entire microchannel. However, the length became around 20% shorter than that before UV illumination when the UV illumination section was limited at the straight portion of the microchannel. The braking effect of liquid flow at the UV–dark border probably plays an important role in this phenomenon.

Keywords: TiO; ₂; UV; Hydrophilicity; Fluidity; Microchannel

Comments on “Multifractal analysis of the fracture surfaces of foamed polypropylene/polyethylene blends” by Saeed Doroudiani (pp. 929-930).

Corrigendum to “SEM/EDX and XPS studies of niobium after electropolishing” by T. Hryniewicz, K. Rokosz, H.R. Zschommler Sandim [Appl. Surf. Sci., yyy (2012) xxx], http://dx.doi.org/10.1016/j.apsusc.2012.09.060 by Tadeusz Hryniewicz; Krzysztof Rokosz (pp. 931-934).

Niobium; Electropolishing (EP); Photoelectron spectroscopy (XPS)

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Applied Surface Science (v.265, #)