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Applied Surface Science (v.258, #1)

Publisher's note (pp. 1-1).

Wafer-level fabrication and optical characterization of nanoscale patterned sapphire substrates by Yu-Sheng Lin; Wen-Ching Hsu; Kuo-Cheng Huang; J. Andrew Yeh (pp. 2-6).

► Wafer-level nanostructures were fabricated atop double-side sapphire substrates. ► The fabrication method was used natural lithography and dry-etching method. ► The optical characterization of nanostructures exhibits a high transmittance. ► Increasing transmittance was over broadband spectra with wide incident angles.The wafer-level aperiodic nanostructures were fabricated atop the sapphire substrates in order to increase the transmittance over broadband spectra. The fabrication was presented along with characterization of their optical properties. The nanostructures were patterned using natural lithography with nickel silicide as a hard mask, and the subsequent etching was performed using inductively coupled plasma dry-etching method. The sapphire substrates with nanostructures compared to conventional sapphire substrates, which exhibit antireflective characteristics over broadband spectra at a wide range of incident angles. The nanostructures reduce the reflection down to 5% in the visible spectrum for normal incidence. The transmittance of visible to near-IR spectra was found to be 94% at normal incidence and over 90% at an incident angle of 45°. In the mid-IR spectrum, the transmittance exceeds 88% until the reflection is no longer suppressed by nanostructures. The polarization properties have also been investigated. The nanostructures can enhance the reflectivity ratio 90% for wavelengths shorter than 400nm. As the amplitude ratio, enhanced from 50% to 80% over the whole visible spectrum.

Keywords: Patterned sapphire; Antireflection; Natural lithography

In situ ellipsometry study of atomic hydrogen etching of extreme ultraviolet induced carbon layers by Juequan Chen; Eric Louis; Rob Harmsen; Tim Tsarfati; Herbert Wormeester; Maarten van Kampen; Willem van Schaik; Robbert van de Kruijs; Fred Bijkerk (pp. 7-12).

► In situ spectroscopic ellipsometry was applied to investigate the etch rate of EUV-induced carbon. ► The high etch rate of the EUV-induced carbon is related to the large hydrogen content. ► A hydrogenating process precedes the removal of carbon by atomic hydrogen. ► Strongest temperature dependence of the etch rate observed on EUV-induced carbon.Atomic hydrogen based etching is generally considered an efficient method for the removal of carbon films resulting from photo-induced hydrocarbon dissociation, as occurs in extreme ultraviolet (EUV) photolithography environments. The etch rate of atomic hydrogen for three different kinds of carbon films was determined, namely for EUV-induced carbon, hot filament evaporated carbon and e-beam evaporated carbon. The etching process was monitored in situ by spectroscopic ellipsometry. The etch rate was found to depend on the type of carbon (polymer or graphite-like), on the layer thickness, and on the temperature. The EUV-induced carbon shows the highest etch rate, with a value of ∼0.2nm/min at a sample temperature of 60°C. The more graphite-like carbon layers showed an etch rate that was about 10 times lower at this temperature. An activation energy of 0.45eV was found for etching of the EUV-induced carbon layer.

Keywords: EUV-induced carbon contamination; Atomic hydrogen etching; Ellipsometry

Structural and morphological dependence of carbon nanotube arrays on catalyst aggregation by Jiang-Tao Di; Zhen-Zhong Yong; Xiao-Jie Yang; Qing-Wen Li (pp. 13-18).

► The thickness of the catalyst film has a direct effect on the areal density of the catalytic particles and then the alignment of the CNT array. ► Both the size and areal density of the catalyst also change with the CNT growth in accordance with Ostwald ripening process, with the bottom of the CNT array varying from well-aligned to disordered and adhesion between catalyst particles and the substrate getting enhanced. ► Introducing alumina as buffer layer and annealing the catalyst film at low pressure are two effective approaches to downsize the catalyst particles and then the diameter, wall number of the CNTs.Catalyst aggregation affects the growth of carbon nanotube (CNT) arrays in terms of tubular structures, waviness, entanglement, lengths, and growth density etc., which are important issues for application developments. We present a systematic correlation between the aggregation of catalyst on the SiO₂/Si substrate and the structure and morphology of CNT arrays. The thickness of the catalyst film has a direct effect on the areal density of the catalytic particles and then the alignment of the CNT array. Introducing alumina as buffer layer and annealing the catalyst film at low pressure are two effective approaches to downsize the catalyst particles and then the diameter, wall number of the CNTs. Both the size and areal density of the catalyst also change with the CNT growth in accordance with Ostwald ripening process, with the bottom of the CNT array varying from well-aligned to disordered and adhesion between catalyst particles and the substrate getting enhanced. Strategies including tuning the thickness of the catalyst film, changing buffer layer, controlling on the growth time and the system pressure were used to regulate the aggregation of the catalyst. CNT arrays from disordered to well-aligned, from multi-walled to few-walled and further to single-walled were reproducibly synthesized by chemical vapor deposition of acetylene.

Keywords: Carbon nanotube; Chemical vapor deposition; Catalyst; Pressure; Aggregation

Correlation between interfacial defects and ferromagnetism of BaTiO₃ nanocrystals studied by positron annihilation by Zhi-Yuan Chen; Z.Q. Chen; D.D. Wang; S.J. Wang (pp. 19-23).

► The above paper reported a detailed study of the structure and magnetic properties of pure BaTiO₃ nanocrystals. ► We confirmed that the ferromagnetism in pure BaTiO₃ is related with interfacial defects. ► The results are important for the understanding of the origin of ferromagnetism in pure BaTiO₃ nanoparticles.High purity BaTiO₃ nanopowders were pressed into pellets and annealed between 100 and 1200°C. The crystal quality and grain size of the BaTiO₃ nanocrystals were characterized by X-ray diffraction measurements. Annealing induces an increase in the grain size from 44 to 82nm with temperature increasing up to 1200°C. XRD and Raman spectroscopy studies confirm that all the samples were single phase with a tetragonal structure after annealing at different temperatures. Positron annihilation measurements reveal large number of vacancy defects in the grain boundary region. These interfacial defects remain stable after annealing at temperatures below 400° C and begin to disappear rapidly above 700°C. After annealing at 1200°C, most of the interfacial defects have been removed. Hysteresis loops are observed for the 100° C annealed samples, which indicate ferromagnetism in BaTiO₃ nanocrystals. The ferromagnetism becomes a little weaker after annealing at 700°C, and it disappears after 1200° C annealing. This change of ferromagnetism coincides with the defect recovery process after annealing, suggesting that ferromagnetism might originate from the interfacial defects.

Keywords: BaTiO; ₃; nanocrystal; Annealing; Interfacial defect; Ferromagnetism

Synthesis and surface properties of submicron barium sulfate particles by Ming Zhang; Bao Zhang; Xinhai Li; Zhoulan Yin; Xueyi Guo (pp. 24-29).

► A fabrication process of submicron BaSO₄ was presented and their surface chemical composition and bonding were studied. ► The effects of the preparation parameters were investigated. ► pH value has significant effect on the particle size. ► An electrical double layer exists around BaSO₄ particle. ► The adsorption of the functional groups of EDTA can shift the isoelectric point of BaSO₄ particle to the lower pH level.Barium sulfate particles were synthesized in the presence of EDTA at room temperature. X-ray diffractometry (XRD), Fourier transform infrared resonance (FTIR) and scanning electron microscopy (SEM) were used to characterize the structure and morphology of BaSO₄ particles. The effect of the preparation parameters on the particle size distribution and morphology was investigated. The conditional formation constants of Ba-EDTA at different pH values were calculated. The results show that the size and morphology of BaSO₄ particles can be effectively controlled by adding EDTA in the precipitation process. Among all the operation conditions, the pH value has significant effect on the particle size. The obtained barium sulfate particles are spherical and well dispersed at pH=9–10. Zeta potentials of BaSO₄ were measured at different pH. The isoelectric point (IEP) of barium sulfate colloid appears at pH 6.92. The model of the solid–solution interface at a particle of BaSO₄ was presented. The FTIR result indicates that the surface of the prepared BaSO₄ absorbs the functional groups of EDTA, which lower the IEP of the barium sulfate particles.

Keywords: Barium sulfate; Precipitation method; Conditional formation constants; Isoelectric point

Optical property investigation of SiGe nanocrystals formed by electrochemical anodization by S.W. Pan; Bi Zhou; S.Y. Chen; Cheng Li; Wei Huang; H.K. Lai (pp. 30-33).

We report on the optical property investigation of SiGe nanocrystals (NCs) prepared by electrochemical anodization (ECA) of SiGe layer grown by ultrahigh vacuum chemical vapor deposition (UHVCVD). At room temperature, SiGe NCs with higher Ge content demonstrate a redshift of the photoluminescence (PL) peak compared to Si NCs. It was found that the surface chemical composition, density, and the size of the SiGe NCs were very sensitive to the annealing conditions. Various spectroscopy measurements such as PL, FTIR, and XPS have been carried out to reveal the mechanism of the PL peak transition. The results indicated that the PL peak position was determined by two major factors, namely, interface state density and the size of SiGe NCs. It was shown that the higher the interface state density, the more significant the redshift of the peak position. While the smaller the size of the SiGe NCs, the more significant the quantum size effects become, resulting in the blueshift of the PL peak position.

Keywords: PACS; S 78.67.−n; S 78.67.Bf; S 78.55.−m; 78.55.MbSiGe nanocrystals; Photoluminescence; Porous SiGe; Mechanism

Preparation and characterization of upconversion luminescent LaF₃:Yb³⁺,Er³⁺/LaF₃ core/shell nanocrystals by Yuqiu Qu; Meicheng Li; Liuyang Zhang; Liancheng Zhao (pp. 34-37).

► Monodisperse LaF₃:Yb³⁺, Er³⁺/LaF₃ core/shell nanocrystals were prepared. ► Upconversion emission intensity and lifetime enhanced after coating with LaF₃ shell. ► Core/shell structure is an efficient way for improving upconversion luminescence.LaF₃:Yb³⁺,Er³⁺/LaF₃ core/shell nanocrystals were successfully synthesized using solvothermal method. The crystal structure, morphology and photoluminescence properties of as-prepared nanocrystals were investigated in detail. XRD patterns show that the obtained LaF₃:Yb³⁺,Er³⁺ core and LaF₃:Yb³⁺,Er³⁺/LaF₃ core/shell nanocrystals exhibit hexagonal structure. The average particle size is about 9.3nm and 11.4nm for core and core/shell nanocrystals, respectively. Compared with LaF₃:Yb³⁺,Er³⁺ nanocrystals, both the upconversion emission intensity and the lifetime increase in LaF₃:Yb³⁺,Er³⁺/LaF₃ core/shell nanocrystals. The enhancement can be attributed to the LaF₃ shell which can eliminate the nonradiative centers on the surface of LaF₃:Yb³⁺,Er³⁺ nanocrystals.

Keywords: Core/shell; Upconversion; LaF; ₃; Nanoparticles

The preparation of c-axis epitaxial Bi-2212 films on STO(100) by sol–gel method by Xiaoming Yu; Huazhe Yang; Yang Qi (pp. 38-43).

► TEA was added to improve properties of sol. ► Experimental parameters such as drying conditions and sintering process were investigated. ► Superconducting property of the film was also investigated. ► Smooth c-axis epitaxial BSCCO films were deposited on STO substrate.Bi₂Sr₂Ca₁Cu₂O8+_δ (Bi-2212) films were grown on (100) oriented SrTiO₃ (STO) substrate using sol–gel spin-coating method. The effects of heat treatment conditions and coating times on the phase formation and surface morphology were investigated using thermal analysis, optical microscope, X-ray diffraction, and scanning electronic microscopy. Mixed phases were formed from 820 to 840°C, and Bi-2212 single phase was obtained at 830°C for 3h. c-axis epitaxial films with smooth surfaces were obtained by drying at 600°C and coating for 5 times.

Keywords: Bi; ₂; Sr; ₂; Ca; ₁; Cu; ₂; O; 8+; _δ; films; STO(1; 0; 0); Sol–gel; Morphology

Self-assembled MnS flower-like hierarchical architectures on porous alumina membrane by Zhijun Wang; Feng Tao; Feng Pan; Yufeng Sun; Weili Cai; Lianzeng Yao (pp. 44-49).

► We aligned MnS nanowires to flower-like hierarchical architectures on the surface of porous alumina membrane (PAM). ► Increasing reaction time, MnS nanowires can be aligned to MnS hollow spheres. ► PAM and gas bubbles formed within the nanopores of PAM is indispensable for the formation of MnS flower-like hierarchical architectures. ► The room-temperature PL spectrum shows a strong emission peak at 420nm corresponding to the MnS band edge emission.MnS flower-like hierarchical architectures were self-assembled on the surface of porous alumina membrane (PAM) under hydrothermal condition. The diameter of MnS flower-like hierarchical architectures is about 2–4μm, which are composed of single-crystal nanowires with width of 70–80nm. X-ray diffraction and high-resolution transmission electron microscopy analysis demonstrated the nanowire have preferred orientation along [110] direction. Prolonged reaction time would result in hollow spheres. Studies show that PAM and gas bubbles formed within the nanopores of PAM under hydrothermal condition play an important role in the formation process of MnS flower-like hierarchical architectures. The room-temperature PL spectrum shows a strong emission peak at 420nm corresponding to the MnS band edge emission.

Keywords: Nanostructures; Crystal growth; Chemical synthesis; Microstructure; Porous alumina membrane

Preparation of honeycomb porous La_0.6Sr_0.4Co_0.2Fe_0.8O3−_δ–Gd_0.2Ce_0.8O2−_δ composite cathodes by breath figures method for solid oxide fuel cells by Naiqing Zhang; Juan Li; Dan Ni; Kening Sun (pp. 50-57).

► Honeycomb porous structured LSCF–GDC composite cathodes are prepared. ► The breath figures method is introduced to prepare SOFC cathode films. ► The ordered micron-sized pores guarantee quick gas transmission.Honeycomb porous La_0.6Sr_0.4Co_0.2Fe_0.8O3−_δ–Gd_0.2Ce_0.8O2−_δ (LSCF–GDC) composite cathodes are prepared using the breath figures (BFs) method with nontoxic and easily available water droplets as templates. The fabrication of honeycomb porous membranes is realized in a relatively humid environment, using a volatile solvent. The microstructure and morphology of the membranes produced are investigated by scanning electron microscopy (SEM). The SEM micrographs suggest that experimental conditions, such as ambient temperature, relative humidity, and concentration of polymer and LSCF–GDC powder, which have direct influence on the solvent evaporation affects the pore structure of the porous membranes. Electrochemical impedance spectroscopy (EIS) is used to evaluate the polarization resistance of LSCF–GDC composite cathodes prepared at different experimental conditions. The honeycomb porous LSCF–GDC composite cathode showing average pore diameter of 10μm illustrates the lowest polarization resistance.

Keywords: Solid oxide fuel cells; Cathode membrane; Breath figures method; Honeycomb porous structure

Electrochemical behavior of amino-modified multi-walled carbon nanotubes coordinated with cobalt porphyrin for the oxidation of nitric oxide by Ya Yan; Pingping Yao; Qin Mu; Lei Wang; Jin Mu; Xiangqing Li; Shi-Zhao Kang (pp. 58-63).

► Cobalt (II) tetrakis (4-sulfonatophenyl) porphyrin could be axially coordinated with ethylenediamine-modified multi-walled carbon nanotubes to form a MWCNT-CoTPPS hybrid. ► The axial coordination between MWCNT and CoTPPS in the MWCNT-CoTPPS hybrid could develop strong bonding force with a benefit to fast electron transfer. ► The MWCNT-CoTPPS modified glass carbon electrode exhibits wide linear range, good stability, and short response time in the electrochemical detection of NO.Cobalt (II) tetrakis (4-sulfonatophenyl) porphyrin (CoTPPS) was axially coordinated with amino-modified multi-walled carbon nanotubes (MWCNT) to form a MWCNT-CoTPPS hybrid. The hybrid was drop cast on the glassy carbon electrode (GCE) to obtain MWCNT-CoTPPS/GCE. The structure of the MWCNT-CoTPPS hybrid was characterized by field-emission transmission electron microscope. X-ray photoelectron spectroscopy was also conducted to characterize the MWCNT-CoTPPS hybrid. Cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry were used to evaluate the electrocatalytic activity of MWCNT-CoTPPS/GCE for the oxidation of nitric oxide (NO). The effects of potential scan rate, temperature and NaNO₂ concentration on the electrochemical oxidation of NO at the MWCNT-CoTPPS/GCE were studied in detail. The obtained MWCNT-CoTPPS/GCE demonstrated a potential application for detecting NO in aqueous solution.

Keywords: Multi-walled carbon nanotubes; Porphyrin cobalt (II); Axial coordination; Electron transfer; Electrochemistry

Structure and magnetism of Zn_0.9Co_0.1O DMS films prepared by chemical solution deposition method by Jinghai Yang; Yan Cheng; Yongjun Zhang; Yaxin Wang; Yang Liu (pp. 64-67).

Display Omitted► All the films have the ZnO wurtzite structure with a preferential orientation along the c-axis. ► Oxygen vacancies, which can induce a donor state overlapping with d states of Co atoms, exist in the films. ► No Co clusters and second phases exit in the films. ► Ferromagnetism is intrinsic behavior which can be explained by the formation of bound magnetic polarons.The Zn_0.9Co_0.1O films are fabricated by chemical solution deposition method. All the films have the ZnO wurtzite structure with a preferential orientation along the c-axis. The analysis of X-ray near-edge absorption spectroscopy and X-ray photoelectron spectroscopy indicates that the valence of Co is +2, and there are oxygen vacancies in Zn_0.9Co_0.1O films annealed in Ar atmosphere. Extended X-ray absorption fine structure results reveal that Co²⁺ ions have dissolved into ZnO and substituted for Zn²⁺ ions. Magnetization measurements show that the film annealed in Ar exhibits ferromagnetism which can be explained by the formation of bound magnetic polarons.

Keywords: Oxygen Vacancy; XANES; EFXAS; Ferromagnetism

Formation of arsenic sulfide on GaAs surface under illumination in acidified thiourea electrolytes by Mahmoud M. Khader; Amina S. AlJaber (pp. 68-75).

► This research is about corrosion inhibition of GaAs semiconductor electrodes by using thiourea acidified electrolytes. ► Thiourea was oxidized on GaAs surface and a corrosion inhibition film of As-sulfide was formed. ► The surface composition of the inhibition film was characterized by XPS. ► Surface morphology was investigated by SEM. ► Electrochemical techniques including impedance measurements were used to investigate GaAs and As-sulfide/GaAs corrosion.The present article reports the formation of arsenic sulfide films on GaAs by the potentiodynamic polarization in acidified thiourea (TU) electrolytes under photo-illumination. Oxidation of TU competes with the oxidation of GaAs itself and leads to the formation of surface arsenic-sulfide films. Surface chemical composition is investigated by X-ray photoelectron spectroscopy (XPS), demonstrating the formation of As-sulfide as the XPS peaks at binding energies of 42.6 and 162.5eV for As 3d and S 2p, respectively, are observed. XPS results also show diminishing of Ga species from the surface while As-sulfide is forming. Though, As-sulfide is predominantly formed on the surface, but the inductive coupling plasma-mass spectroscopy (ICP-MS) analysis still shows a preferential dissolution of As ions into electrolytes. These results indicate that Ga ions diffuse into the bulk of the electrode material. The formation of As-sulfide, initially, enhances the photocurrent generation; presumably, due to suppressing electron-hole recombination processes. Further deposition of As-sulfide deteriorates GaAs photoactivity due to retarding light absorptivity because of depositing a thick As-sulfide film. The morphology of the As-sulfide film is characterized by scanning electron microscopy (SEM) that shows the formation of smooth and nonporous films in TU electrolytes acidified by H₂SO₄ of concentration ≥0.2M. Electrochemical impedance measurements show that GaAs corrosion is limited by the growth and oxidation of the sulfide layer.

Keywords: GaAs; As-sulfide; Corrosion; Impedance; XPS

The effect of pre-pattern on the morphology and growth speed of TiO₂ nanotube by Tao Xu; Jia Lin; Jingfei Chen; Xianfeng Chen (pp. 76-80).

► Grating ruling engine was utilized to make pre-patterns on the surface of Ti sheet. ► Growth speeds of the TiO₂ nanotube on the Ti sheets with pretreatments were accelerated. ► A novel wall structure which increased the surface-to-volume ratio was formed. ► The method maybe useful in the further optimization of fast growth of TiO₂ nanotube. ► The wall structure has potentials in improving the efficiency of dye-sensitized solar cell and photocatalysis.In this work, we presented a new method which directly acts on the surface of the Ti sheet by mechanical micro-etching using a grating ruling engine. The effect of the pre-pattern on the morphology and growth speed of TiO₂ nanostructure formed on the Ti sheet with the traditional anodization method was investigated. A novel wall structure was observed and the growth speed of TiO₂ nanotube (NT) was greatly affected by the pre-pattern. The wall structure increases the surface-to-volume ratio of the nanotube arrays. The new method provided the possibility of further optimization of fast growth of TiO₂ nanostructure and improving the efficiency of dye-sensitized solar cell (DSSC) and photocatalysis.

Keywords: Nanotube; TiO; ₂; Pre-pattern; Mechanical etching; Morphology

Constituted oxides/nitrides on nitriding 304, 430 and 17-4 PH stainless steel in salt baths over the temperature range 723 to 923K by Teng-Shih Shih; Yung-Sen Huang; Chi-Fan Chen (pp. 81-88).

Display Omitted► For a given nitriding process, 17-4 PH stainless steel obtained a thickest nitrided film among three samples used in this study. ► The constituted phases situated in the nitrided films on 304, 430 and 17-4 PH stainless steels were analysed and reported. ► The highest N 1s counts were detected from the nitrided film on the 17-4 PH stainless steel.The progressively developed oxides and nitrides that form on nitriding 304, 430 and 17-4 PH stainless steel are analysed by X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) in this study. The experimental results show that the Cr contents and matrix structures (ferrite, austenite and martensite) play an important role in forming FeCr₂O₄, Cr₂O₃ and Fe₂O₃ oxides as well as nitrides. After a short immersion time, oxides of Cr₂O₃ and FeCr₂O₄ form in nitride films on 304 stainless steel samples. Fe₂O₃ oxide will subsequently form following an increasing immersion time. For the 430 stainless steel, Cr₂O₃ predominately forms after a short dipping time which hinders the growth of the nitride layer. As a result, this sample had the thinnest nitride film of the three for a given immersion time. After the formation of oxides, both CrN and Cr₂N were detected near the surface of the nitride films of three samples while Cr₂N phases formed in the deeper zone. The greatest amount of Fe₂O₃ oxide among the three samples was obtained on the nitriding 17-4 PH stainless steel which also had a high intensity count of N 1s.

Keywords: Nitriding; X-ray photoelectron spectroscopy; FeCr; ₂; O; ₄; Cr; ₂; O; ₃; Fe; ₂; O; ₃; Cr; ₂; N

Preparation of nanowall Bi₂S₃ films by chemical bath deposition by Chao Gao; Honglie Shen; Lei Sun (pp. 89-92).

► Bi₂S₃ films with novel nanowall structure were prepared by chemical bath deposition. ► It is found that the pH value (pH=6 or pH=6.5) of the solution is a crucial parameter to obtain the nanowall shaped Bi₂S₃ films. ► The structures, morphologies, optical properties and electrical properties of the Bi₂S₃ films were studied. ► The nanowall Bi₂S₃ films show obvious photo-sensitivity, and the photo-to-dark conductivity ratio of the films is around 50.Nanowall shaped Bi₂S₃ films were prepared by chemical bath deposition in which ammonium citrate and thioacetamide were used as chelating reagent and sulfur source, respectively. The nanowall Bi₂S₃ films show large-surface-area nanowall shaped morphology. It is found that the pH value (pH=6 or pH=6.5) of the solution is a crucial parameter to obtain the nanowall shaped Bi₂S₃ films. The composition of the nanowall Bi₂S₃ films is close to the stoichiometric ratio of Bi₂S₃. The absorption edge of the nanowall shaped Bi₂S₃ films is located at around 900nm, indicating that the optical bandgap of the Bi₂S₃ films is around 1.4eV. The nanowall Bi₂S₃ films show obvious photo-sensitivity. The photo-to-dark conductivity ratios of the nanowall Bi₂S₃ films prepared at pH=6 and pH=6.5 are all around 50. This value is around five times than that of the non-nanowall shaped Bi₂S₃ films which is prepared at pH=7.

Keywords: Bismuth sulfide; Thin films; Chemical bath deposition; Nanostructure

Synthesis and optical properties of ZnO nanorods on indium tin oxide substrate by J.H. Zheng; Q. Jiang; J.S. Lian (pp. 93-97).

► ZnO nanorods were synthesized by thermal evaporation without catalyst or additives. ► The ZnO nanorods show good crystallinity testified by the Raman spectrum. ► The ZnO nanorods show strong UV emission with slight light emission in PL spectrum.ZnO nanorods with uniform diameter and length have been synthesized on an indium-tin oxide (ITO) substrate by using a simple thermal evaporation method which is suitable to larger scale production and without any catalyst or additives. The samples were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–vis (UV–vis) absorption spectrum, photoluminescence (PL) spectrum and Raman spectrum. The single-phase ZnO nanorods grow well-oriented along the c-axis of its wurtzite structure on ITO substrate. The ZnO nanorods shows sharp and strong UV emission located at 380nm without notable visible light emission in the PL spectrum, which suggests the good crystallinity of the nanorods, which was also testified by their Raman spectrum. The photodegradation of methylene orange (MO) in aqueous solution reveals that the well-arranged c-axis growth of ZnO nanorods possess evidently improved photocatalytic performance and these properties enable the ZnO nanorods potential application in UV laser.

Keywords: ZnO nanorods; Photocatalytic activity; Optical properties; Thermal evaporation method

Surface modification of PMMA/O-MMT composite microfibers by TiO₂ coating by Qingqing Wang; Xin Wang; Xuejia Li; Yibing Cai; Qufu Wei (pp. 98-102).

► Sputtering coating with titanium dioxide (TiO₂) functionalizes the surface of the electrospun poly(methyl methacrylate) (PMMA)/organically modified montmorillonite (O-MMT) composite microfibers. ► The deposition of anatase-TiO₂ and rutile-TiO₂ nanoparticles changes surface chemical and physical properties of the electrospun PMMA/O-MMT composite microfibers. ► TiO₂ deposition enables the photocatalytic degradation of methylene blue.In the present work, poly(methyl methacrylate) (PMMA)/organically modified montmorillonite (O-MMT) composite microfibers were firstly prepared by emulsion polymerization combined with electrospinning, and then coated by nanosize titanium dioxide (TiO₂) using RF magnetron sputter technique. The modified surfaces of PMMA/O-MMT composite microfibers were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), UV–vis spectroscopy and drop shape analyzer. Finally, the photocatalytic properties of TiO₂ coated PMMA/O-MMT composite microfiber membranes were evaluated by degradation of methylene blue(MB) under UV illumination. The experimental results revealed that anatase-TiO₂ and rutile-TiO₂ nanoparticles were well spread and physically deposited on the surface of PMMA/O-MMT microfibers, and the wettability of the PMMA/O-MMT composite microfibers was improved after surface modification by sputter coating. Furthermore, the PMMA/O-MMT microfibers membrane coated with TiO₂ performed well in photocatalytic degradation of MB.

Keywords: Electrospinning; RF(ratio frequency) magnetron sputtering; TiO; ₂; Microfibers; Water treatment

Influence of Ni deposition and subsequent N⁺ ion implantation at different substrate temperatures on nano-structure and corrosion behaviour of type 316 and 304 stainless steels by Hadi Savaloni; Maryam Habibi (pp. 103-112).

► Enhancement of corrosion resistance of stainless steel by nickel nitride coating. ► Correlation between the structural analyses and the potentiodynamic results is achieved. ► Optimum corrosion results is achieved for critical surface roughness and annealing temperature.Ni thin films of 250nm thicknesses were coated on type 304 and 316 stainless steels and post N⁺ ion implanted at 15keV energy with a fluence of 5×10¹⁷N⁺cm⁻² at different substrate temperatures. Surface nano-structure of the samples were analysed using X-ray diffraction (XRD), atomic force microscopy (AFM) before corrosion test and scanning electron microscopy (SEM) after corrosion test. Corrosion behaviour of the samples in 1.0M H₂SO₄ solution was investigated by means of potentiodynamic technique. Nano-structure and crystallography of the films showed the development of Ni₃N(111) and Ni₄N(200) orientations with a minimum surface roughness and grain size at 400K substrate temperature. The highest corrosion resistance with a corrosion current of 0.01μAcm⁻² (for SS(316)) and 0.56μAcm⁻² (for SS(304)) was achieved in case of samples which were N⁺ ion implanted at 400K. Results for both types of stainless steels showed good agreement and the better performance of SS(316) was attributed to the 2% molybdenum contents in the alloy composition of this type of stainless steel, which enhances the effectiveness of nitrogen in retarding the corrosion process.

Keywords: Stainless steel; Ion implantation; Corrosion; PVD coating; AFM

Tribological behavior of micro/nano-patterned surfaces in contact with AFM colloidal probe by Xiaoliang Zhang; Xiu Wang; Wen Kong; Gewen Yi; Junhong Jia (pp. 113-119).

► Micro/nano-patterned surfaces with ordered cylindrical pillars were fabricated by replica molding technique. ► The friction force images for micro/nano-patterned surfaces were obtained by AFM technique using colloidal probes. ► A difference in friction force produced a contrast on the friction force images when the colloidal probe slid over different regions of the patterned polymer surfaces. ► When the size of colloidal probe was larger than the spacing between the pillars, the colloidal probe remained in contact with pillars, thus the probe-substrate contact area was reduced, leading to reduced friction during scanning.In effort to investigate the influence of the micro/nano-patterning or surface texturing on the nanotribological properties of patterned surfaces, the patterned polydimethylsiloxane (PDMS) surfaces with pillars were fabricated by replica molding technique. The surface morphologies of patterned PDMS surfaces with varying pillar sizes and spacing between pillars were characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). The AFM/FFM was used to acquire the friction force images of micro/nano-patterned surfaces using a colloidal probe. A difference in friction force produced a contrast on the friction force images when the colloidal probe slid over different regions of the patterned polymer surfaces. The average friction force of patterned surface was related to the spacing between the pillars and their size. It decreased with the decreasing of spacing between the pillars and the increasing of pillar size. A reduction in friction force was attributed to the reduced area of contact between patterned surface and colloidal probe. Additionally, the average friction force increased with increasing applied load and sliding velocity.

Keywords: Micro/nano-patterned surfaces; Friction; Polymer; AFM

A comparative study of solution based CIGS thin film growth on different glass substrates by Se Jin Park; Eunjoo Lee; Hyo Sang Jeon; Se Jin Ahn; Min-Kyu Oh; Byoung Koun Min (pp. 120-125).

A comparative study of solution based CIGS thin film growth on different glass substrates.Display Omitted► CuIn_xGa1−_xSe_yS2−_y (CIGS) thin films were synthesized on glass substrates by a solution process. ► Morphologies of CIGS films were investigated with respect to the kinds of glass substrates. ► CIGS film on Mo-coated glass showed large grains with an undesired Mo oxide interfacial layer. ► CIGS film on FTO glass was porous and composed of relatively small grains. ► Higher power conversion efficiency was attained by the CIGS film grown on Mo-coated glass.CuIn_xGa1−_xSe_yS2−_y (CIGS) thin films were synthesized on glass substrates by a paste coating of Cu, In, and Ga precursor solution with a three-step heat treatment process: oxidation, sulfurization, and selenization. In particular, morphological changes of CIGS films for each heat treatment step were investigated with respect to the kinds of glass substrates: bare, Mo-coated, and F-doped SnO₂ (FTO) soda-lime glasses. Very high quality CIGS film with large grains and low degree of porosity was obtained on the bare glass substrate. Similar morphology of CIGS film was also acquired on the Mo-coated glass except the formation of an undesired Mo oxide interfacial layer due to the partial oxidation of Mo layer during the first heat treatment under ambient conditions. On the other hand, CIGS film with much smaller grains and higher degree of porosity was gained when FTO glass was used as a substrate, resulting in slight solar to electricity conversion behavior (0.20%). Higher power conversion efficiency (1.32%) was attained by the device with the CIGS film grown on Mo-coated glass in spite of the presence of a Mo oxide impurity layer.

Keywords: CIGS; CuIn; _x; Ga; _1-x; Se; _y; S; _2-y; Substrates; Solar cells; Solution processes

Enhancement of hydrophobicity and tensile strength of muga silk fiber by radiofrequency Ar plasma discharge by D. Gogoi; A.J. Choudhury; J. Chutia; A.R. Pal; N.N. Dass; D. Devi; D.S. Patil (pp. 126-135).

► Radiofrequency (RF) Ar plasma treatment for improvement in hydrophobicity and tensile strength of muga silk fiber. ► Investigation of the properties of the fibers treated at various RF powers (10–30W) and treatment times (5–20min). ► Increase in RF power rather than treatment time affects the chemical composition of the fibers. ► The treated muga fibers exhibit almost similar thermal behavior as compared to the virgin one. ► Correlation of the properties of plasma treated fibers with XPS and their surface morphologies.The hydrophobicity and tensile strength of muga silk fiber are investigated using radiofrequency (RF) Ar plasma treatment at various RF powers (10–30W) and treatment times (5–20min). The Ar plasma is characterized using self-compensated Langmuir and emissive probe. The ion energy is observed to play an important role in determining the tensile strength and hydrophobicity of the plasma treated fibers. The chemical compositions of the fibers are observed to be affected by the increase in RF power rather than treatment time. XPS study reveals that the ions that are impinging on the substrates are mainly responsible for the cleavage of peptide bond and side chain of amino acid groups at the surface of the fibers. The observed properties (tensile strength and hydrophobicity) of the treated fibers are found to be dependent on their variation in atomic concentration and functional composition at the surfaces. All the treated muga fibers exhibit almost similar thermal behavior as compared to the virgin one. At RF power of 10W and treatment time range of 5–20min, the treated fibers exhibit properties similar to that of the virgin one. Higher RF power (30W) and the increase in treatment time deteriorate the properties of the fibers due to incorporation of more surface roughness caused by sufficiently high energetic ion bombardment. The properties of the plasma treated fibers are attempted to correlate with the XPS analysis and their surface morphologies.

Keywords: Radiofrequency plasma; Muga fiber; Self-compensated Langmuir and emissive probe; Ion energy; Hydrophobicity; Tensile strength

Effect of cross-linkable polymer on the morphology and properties of transparent multi-walled carbon nanotube conductive films by Yuan-Li Huang; Hsi-Wen Tien; Chen-Chi M. Ma; Chih-Chun Teng; Yi-Hsiuan Yu; Shin-Yi Yang; Ming-Hsiung Wei; Sheng-Yen Wu (pp. 136-142).

.Display Omitted► Poly(acrylic acid) and poly(N-vinyl pyrrolidone) were used as a polymer binder layer. ► The cross-linked polymer resulted in a better bond between the MWCNTs and substrates. ► MWCNTs constitute more complete conductive paths with the cross-linked polymer. ► The better binding addresses the health and safety concerns regarding free MWCNTs.In this study, we fabricated optically transparent and electrically conductive multi-walled carbon nanotube (MWCNT) thin films using a spray-coating technique. The transparency and the electrical resistance of thin film are dependent on the nanotube content deposited on the polyethylene terephthalate (PET) substrate. Poly(acrylic acid) (PAA) and poly(N-vinyl pyrrolidone) (PVP) were used as adhesion promoters to improve MWCNT coating more significantly. The cross-linked polymer resulted in a superior bond between the MWCNTs and the substrates. The surface electrical resistance was significantly lower than the original sheet after nitric acid (HNO₃) treatment because of the removed surfactant and the increased interconnecting networks of MWCNT bundles, thus improving the electrical and optical properties of the films. Stronger interaction between the MWCNTs and the substrates resulted in lower decomposition of the polymer chain and less amounts of MWCNTs separated into the HNO₃ solution. The lower sheet electrical resistance of PVP/PAA-g-MWCNT conductive films on the PET substrate was because of a more complete conductive path with the cross-linked polymer than that without. Such an improved sheet of electrical resistance varied from 8.83×10⁴Ω/□ to 2.65×10³Ω/□ with 5.0wt.% PVP/PAA-g-MWCNT sprayed on the PET after acid treatment.

Keywords: Carbon nanotubes; Cross-linked polymer; Adhesion promoter; Transparent conductive thin films

Ultraviolet photoelectron spectroscopy of nano In clusters Schottky barriers on sputtered InP by Shailendra Kumar; C. Mukherjee; V.K. Dixit; S.D. Singh; S.N. Jha (pp. 143-146).

► Ultraviolet photoelectron spectroscopy is used to study effect of nano In clusters on photoelectron spectra of sputtered InP wafers. ► Plasmon peak is observed in the presence of nano In clusters. However, filled energy levels at the Fermi level are not observed. ► Results will be useful in study of epitaxial layers deposited on InP.Plasmon peaks along with Auger P_LVV peak have been observed in the ultraviolet photoelectron spectra (UPSs) of InP after 5min of sputtering with 0.5kV Ar⁺ ions. Plasmon and Auger peaks are not observed in UPS of un-sputtered InP surface with native oxides of In and P. Filled electron energy levels are not observed near the Fermi level from 5min sputtered InP surface due to increase of ionization potential of nano In clusters.

Keywords: Nano cluster; Plasmon; Photoelectron spectroscopy

Investigation of the surface properties of gold nanowire arrays by Huijun Yao; Dan Mo; Jinglai Duan; Yonghui Chen; Jie Liu; Youmei Sun; Mingdong Hou; Thomas Schäpers (pp. 147-150).

Display Omitted► The gold nanowire arrays were prepared in ion-track template and the optical properties were studied with the gold nanowires still embedded in the template. ► The chemisorbed oxygen on the surface of gold nanowires was suggested through surface plasmon resonance and XPS analysis. ► The final-state effect on gold nanowire arrays caused by PC template were studied assist with XPS.Gold nanowire arrays with diameters ranging from 45 to 200nm were obtained via electrochemical deposition within the ion-track templates. The morphology of gold nanowires was imaged by scanning electron microscopy (SEM). The surface properties were investigated by surface plasmon resonance (SPR) and X-ray photoelectron spectroscopy (XPS). The SPR peaks were observed as the gold nanowire arrays embedded in the templates and their intensity decreased after the sample exposed to the air for a certain time due to the formation of chemisorbed oxygen on nanowire surface. The positive binding energy shifts in Au core level was found when the gold nanowire arrays embodied in template and the initial- and finial-state effects were introduced to explain this phenomenon.

Keywords: Gold nanowires; Surface plasmon resonance (SPR); XPS

Structural and optical properties of Au-implanted ZnO films by X.D. Zhang; P. Wu; Y.Y. Shen; L.H. Zhang; Y.H. Xue; F. Zhu; D.C. Zhang; C.L. Liu (pp. 151-157).

► 530nm green luminescence band has been observed in the Au-implanted and subsequently annealed ZnO films. ► Au⁰ is dominant state in Au implanted and annealed ZnO films. ► Band edge of Au-implanted ZnO has shifted to high energy range and optical band gap has increased.The structural and luminescence related optical behaviours of Au ion implanted ZnO films grown by magnetic sputtering and their post implantation annealing behaviours in the temperature range of 100–700°C have been investigated. Optical absorption and transmittance spectra of the films indicate that band edge of Au-implanted ZnO has shifted to high energy range and optical band gap has increased, because the sharp difference of thermal expansion induces the lattice mismatch between ZnO and SiO₂. PL spectra reveal that UV and visible luminescence bands of ZnO films can be improved after thermal annealing due to recovery of defects and Au ions incorporation. Importantly, green luminescence band of 530nm has been only observed in the Au-implanted and subsequently annealed ZnO films and it enhances with the increasing annealing temperature, which can be related to Au atoms or clusters in ZnO films. Furthermore, X-ray photoelectron spectroscopy measurements reveal that the Au⁰ is dominant state in Au implanted and annealed ZnO films. Possible mechanisms, such as optical transitions of Au atoms or clusters and deep level luminescence of ZnO, have been proposed for green emission.

Keywords: PACS; 78.55.Et; 73.61.Ga; 78.20.Ci; 61.72.VvZnO film; Au ion implantation; Optical properties

Optically transparent, superhydrophobic methyltrimethoxysilane based silica coatings without silylating reagent by Mahendra S. Kavale; D.B. Mahadik; V.G. Parale; P.B. Wagh; Satish C. Gupta; A.Venkateswara Rao; Harish C. Barshilia (pp. 158-162).

.Display Omitted► Contact angle value reached up to 171°. ► Thermal conductivity of the silica coating is 0.089Wm⁻¹K⁻¹. ► The superhydrophobic coatings stable up to 457°C. ► The optical transmission study shows coatings have nearly 91% transmission in the visible region.The superhydrophobic surfaces have drawn lot of interest, in both academic and industries because of optically transparent, adherent and self-cleaning behavior. Surface chemical composition and morphology plays an important role in determining the superhydrophobic nature of coating surface. Such concert of non-wettability can be achieved, using surface modifying reagents or co-precursor method in sol–gel process. Attempts have been made to increase the hydrophobicity and optical transparency of methyltrimethoxysilane (MTMS) based silica coatings using polymethylmethacrylate (PMMA) instead of formal routes like surface modification using silylating reagents. The optically transparent, superhydrophobic uniform coatings were obtained by simple dip coating method. The molar ratio of MTMS:MeOH:H₂O was kept constant at 1:5.63:1.58, respectively with 0.5M NH₄F as a catalyst and the weight percent of PMMA varied from 1 to 8. The hydrophobicity of silica coatings was analyzed by FTIR and contact angle measurements. These substrates exhibited 91% optical transmittance as compared to glass and water drop contact angle as high as 171±1°. The effect of humidity on hydrophobic nature of coating has been studied by exposing these films at relative humidity of 90% at constant temperature of 30°C for a period of 45 days. The micro-structural studies carried out by transmission electron microscopy (TEM).

Keywords: Sol–gel process; Superhydrophobic substrates; PMMA; Transparent coatings

A facile strategy for the fabrication of uniform CdS nanowires with high yield and its controlled morphological growth with the assistance of PEG in hydrothermal route by Kaushik Pal; Uday Narayan Maiti; Tapas Pal Majumder; Subhas Chandra Debnath (pp. 163-168).

► We have synthesized CdS nanostructure through simple one step solvothermal route. ► The morphology of the nanostructures were tailored through surfactant as well as growth time. ► The morphology dramatically changes from 1D wire like structure to 2D flakelike structure with very high surfactant content. ► All the nanostructures exhibit good optical quality.A series of novel wurtzite cadmium sulphide (CdS) nanowires with uniform diameter were synthesized by using a rapid and simple solvothermal route. CdS nano structures with certain morphology could be selectively produced by only varying the concentration of poly ethylene glycol (PEG) as a surfactant in the reaction system with cadmium acetate, sulphur powder and ethelynediamine (EDA). We extensively studied UV–vis absorption spectra, photoluminescence spectra after confirming CdS nanowires with diameter 24–25nm and length ranging up to several nano meters by field emission scanning electron microscopy (FE-SEM). Therefore we may definitely propose a new formation mechanism of CdS nanowires assisted by PEG with its illustrating optical properties.

Keywords: CdS nanowire; Photoluminescence Spectroscopy; XRD; Chemical synthesis

KrF laser ablation of a polyethersulfone film: Effect of pulse duration on structure formation by Hedieh Pazokian; Alexandros Selimis; Emmanuel Stratakis; Mahmoud Mollabashi; Jalal Barzin; Saeid Jelvani (pp. 169-175).

► The early stages of structure formation on polyethersulfone (PES) surface following KrF laser irradiation depend on the pulse duration. ► The number density of the cones increases with number of pulses in the ns case while it decreases upon ultra-short pulse (fs and ps) irradiation. ► The chemical compositions induced in the laser treated surfaces depend on pulse duration. ► Control of PES surface morphology upon KrF laser irradiation can be attained by proper combination of pulse duration and number of pulses.Polyethersulfone (PES) films were processed with KrF laser irradiation of different pulse durations ( τ). Scanning electron microscopy (SEM) and Raman spectroscopy were employed for the examination of the morphology and chemical composition of the irradiated surfaces, respectively. During ablation with 500fs and 5ps pulses, localized deformations (beads), micro-ripple and conical structures were observed on the surface depending on the irradiation fluence ( F) and the number of pulses ( N). In addition, the number density of the structures is affected by the irradiation parameters ( τ, F, N). Furthermore, at longer pulse durations ( τ=30ns), conical structures appear at lower laser fluence values, which are converted into columnar structures upon irradiation at higher fluences. The Raman spectra collected from the top of the structures following irradiation at different pulse durations revealed graphitization of the ns laser treated areas, in contrast to those processed with ultra-short laser pulses.

Keywords: Polyethersulfone; KrF laser; Structure formation; Pulse duration

Ion-induced secondary electron emission from ZnS thin films deposited by closed-spaced sublimation by M. Ashraf; S. Ullah; S. Hussain; A.H. Dogar; A. Qayyum (pp. 176-181).

► ZnS films of same chemical composition and various energy band gaps were prepared by close-spaced sublimation. ► Ion-induced secondary electron yield of ZnS films was measured. ► Secondary electron yield of ZnS films was quite high as compared to metals. ► Secondary electron yield of ZnS films having same composition was different. ► The dissimilar electron yields are due to the energy band gap, surface barrier potential and density of the films.ZnS thin films were deposited on soda lime glass and aluminum substrates by close-spaced sublimation technique. The change in composition, structural and optical properties of the films was investigated as a function of the substrate temperature. The deposited films were stoichiometric and crystalline in nature having cubic structure oriented only along (111) plane. The energy band gap of the films deposited at the substrate temperature of 150, 250 and 350°C was 3.52, 3.58 and 3.63eV respectively. These films were then bombarded with 2–10keV energy pulsed Ar⁺ beam and their electron yield was determined from impinging ion and emitted electron currents. The electron yield of ZnS films was much high as compared to the metals. The electron yield of ZnS films increased with energy of the incident ion and got saturated at about 8keV. The most important result of this study was that the electron yield of ZnS films having same composition was different. Monte Carlo simulations performed to interpret these experimental findings showed that the dissimilar electron yields of ZnS films is due to the combined effect of energy band gap, surface barrier potential and density of the films.

Keywords: PACS; 78.20.Ci; 78.66.−w; 78.66.Hf; 79.20.Rf; 79.20.ApZnS films; Energy band gap; Ion-induced electron emission; Monte Carlo simulation

Enhanced photocatalytic activity and stability of nano-scaled TiO₂ co-doped with N and Fe by Shaozheng Hu; Fayun Li; Zhiping Fan; Chein-Chi Chang (pp. 182-188).

The N, Fe co-doped TiO₂ exhibited a much higher photocatalytic activity than doped samples with nitrogen or Fe³⁺ alone.Display Omitted► N, Fe co-doped TiO₂ was prepared via modified sol–gel process. ► The Ti–O–Si bond formed between TiO₂ and MCM-41 fixed the TiO₂ on the MCM-41 surface. ► Excessive nitridation treatment caused the decreased doping N content and photocatalytic activity. ► N, Fe co-doped TiO₂ showed much higher activity than doped samples with nitrogen or Fe³⁺ alone.Titanium dioxide (TiO₂) nanoparticles co-doped with N and Fe were prepared via modified sol–gel process. The products were characterized by transmission electron microscopy (TEM), N₂ adsorption, X-ray diffraction (XRD), Raman spectroscopy, UV–vis spectroscopy, photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS). It is shown that the prepared TiO₂ particles were less than 10nm with narrow particle size distribution. The addition of MCM-41 caused the formation of Ti–O–Si bond which fixed the TiO₂ on MCM-41 surface, thus restricted the agglomeration and growth of TiO₂ particles. The photocatalytic performance in the degradation of methylene blue showed that N, Fe co-doped TiO₂ exhibited much higher photocatalytic activity than doped sample with nitrogen or Fe³⁺ alone under both UV and visible light. N, Fe co-doping decreased the loss of doping N during the degradation reaction, thus increased the photocatalytic stability. It was also found that the nitridation time had significant influence on the photocatalytic activity of prepared TiO₂ catalysts.

Keywords: Titanium dioxide; Co-doped; Photocatalysis; Fe; ³⁺; Nitrogen; Stability

Template-free synthesis of ZnV₂O₄ hollow spheres and their application for organic dye removal by Fang Duan; Weifu Dong; Dongjian Shi; Mingqing Chen (pp. 189-195).

► Hollow ZnV₂O₄ spheres were fabricated by a facile one-step template-free solvothermal treatment. ► A flowerlike intermediate product supported reduction–dissolution–aggregation process is proposed to describe the formation of ZnV₂O₄ hollow spheres. ► ZnV₂O₄ hollow spheres were used as adsorbent for effective removal of organic dyes in simulated wastewater.Hollow ZnV₂O₄ spheres with the shell aggregated by small nanoparticles were successfully synthesized through a facile one-pot template-free solvothermal method. The as-prepared product was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and Brunauer–Emmett–Teller N₂ adsorption–desorption analyses. The formation of ZnV₂O₄ hollow spheres was based on flowerlike intermediate products supported reduction–dissolution–aggregation process at the expense of consumption of all the flowerlike products. The obtained ZnV₂O₄ hollow spheres showed a good adsorption capacity of methylene blue (MB) organic dye, which might be attributed to their special structural feature with large surface area. The adsorption kinetics and isotherm of MB on ZnV₂O₄ hollow spheres were also studied.

Keywords: ZnV; ₂; O; ₄; Hollow spheres; Adsorption; Kinetics

The research and preparation of a novel nano biodegradable polymer external reinforcement by Xiangman Zhang; Bin Chen; Weiguo Fu; Zhengdong Fang; Zhenjie Liu; Weifeng Lu; Zhengyu Shi; Lili Chen; Tao Chen (pp. 196-200).

► The drug loaded vascular external graft was synthesized with electrospinning scaffolds and triblock copolymer micelles. ► GPG micelles may influence cell differentiation when concentration exceed 20μg/mL. ► The micelles coated electrospinning scaffolds provided good support for cell growth under the percentages 10% w/w% (GPG:PLCL–fibrinogen). ► Micelles coated electrospinning scaffold have a great potential for vascular tissue engineering application in the future.The use of current drug-loaded vascular scaffolds is limited in sustained drug release and stability studies in clinical and preclinical trials. We found that poly(l-glutamic acid)-b-poly(propylene oxide)-b-poly(l-glutamic acid) (PLGA-b-PPO-b-PLGA) triblock copolymers can deliver multiple poorly water-soluble drugs (e.g., Paclitaxel) at clinically relevant doses. In this study, we synthesized a new drug-loaded vascular external graft with electrospun nanofibrous scaffolds [poly(l-lactide-co-ɛ-caprolactone) (PLCL):fibrinogen; 2:1 (w/w)] and drug-loaded PLGA-b-PPO-b-PLGA micelles. Cell proliferation and viability assay results showed that beagle smooth muscle cells grew well on the surface of vascular graft-coated micelles at a percentages of 10% (w/w) GPG:PLCL–fibrinogen. This study demonstrates that micelle-coated electrospun PLCL–fibrinogen vascular scaffolds have potential applications in vascular tissue engineering.

Keywords: Electrospun; Micelles; Tissue engineering

Formation of CuO nanowires by thermal annealing copper film deposited on Ti/Si substrate by Yao Wang; Ruiqi Shen; Xiaoyun Jin; Peng Zhu; Yinghua Ye; Yan Hu (pp. 201-206).

► Copper films are deposited by electron beam evaporation. ► Nanowires are synthesized by thermal annealing of copper film. ► The growth of nanowires depends on thermal time, thermal temperature, and film thickness.Nanowires of various inorganic materials have been fabricated due to the realization of their applications in different fields. Large-area and uniform cupric oxide (CuO) nanowires were successfully synthesized by a very simple thermal oxidation of copper thin films. The copper films were deposited by electron beam evaporation onto Ti/Si substrates, in which Ti film was first deposited on silicon substrate to serve as adhesion layer. The structure characterization revealed that these nanowires are monoclinic structured single crystallites. The effects of different growth parameters, namely, annealing time, annealing temperature, and film thickness on the fabrication of the CuO nanowires were investigated by scanning electron microscopy. A typical procedure simply involved the thermal oxidation of these substrates in air and within the temperature range from 300 to 700°C. It is found that nanowires can only be formed at thermal temperature of 400°C. It is observed that the growth time has an important effect on the length and density of the CuO nanowires, whereas the average diameter is almost the same, i.e.50nm. Different from the vapor–liquid–solid (VLS) and vapor–solid (VS) mechanism, the growth of nanowires is found to be based on the accumulation and relaxation of the stress.

Keywords: CuO nanowires; Thermal annealing; Electron beam evaporation; Growth mechanism

Quenching influence of cell culture medium on photoluminescence and morphological structure of porous silicon by Bayram Unal (pp. 207-211).

► Porous silicon was prepared by stain-etching using a HF:HNO₃ solution. ► Photoluminescence of porous silicon under the influential actions of cell culture medium was studied for degradation effects. ► B50 rat hippocampal neuron cell was cultured over visible photoluminescent porous surfaces. ► Porous silicon was used for direct culturing over nanostructured morphology.In this work, the degradation of visible photoluminescence of porous silicon (PSi) under the influential actions of cell culture medium has been mainly studied in order to comprehend the quenching mechanisms necessitating the cell growth on spongy-like-silicon structures, which could form either micro- and/or nano-dimensional morphologies after stain-etching of the poly- or single-crystalline Si surfaces. Quenching effect of the neuron culture medium on visibly luminescent and non-luminescent porous silicon is found to be quite obvious so that this step of the culture process, especially, over nanostructured silicon is extremely essential for a variety of bionanotechnological applications.

Keywords: Porous silicon; Neurons; Photoluminescence; SEM micrographs

Facile preparation of Au/Ag bimetallic hollow nanospheres and its application in surface-enhanced Raman scattering by Zao Yi; Xibin Xu; Xibo Li; Jiangshan Luo; Weidong Wu; Yongjian Tang; Yougen Yi (pp. 212-217).

Au/Ag bimetallic hollow nanospheres were synthesized by modified SiO₂ nanoparticle-templating method at room temperature. The as-prepared hollow Au/Ag nanospheres structured films were used for the first time as SERS substrates and exhibited good SERS enhancement ability.Display Omitted► Hollow Au/Ag bimetallic nanospheres were synthesized using a modified SiO₂ nanoparticle-templating method. ► The as-prepared hollow Au/Ag nanospheres structured films are used for the first time as SERS substrates. ► They exhibit good SERS enhancement ability, excellent reproducibility, and stability, which may find practical application for routine SERS analysis. ► The Au/Ag bimetallic hollow nanostructured aggregate, interconnected nanostructured aggregate and nanoscale roughness are important factors for SERS enhancement ability.In this paper, an Au/Ag bimetallic hollow nanostructure was obtained by using SiO₂ nanospheres as sacrificial templates. The nanostructure was fabricated via a three steps method. SiO₂@Au nanospheres were first synthesized by the layer-by-layer technique, and then they were coated with a layer of Ag particles, finally, the Au/Ag bimetallic hollow nanospheres were obtained by dissolution of the SiO₂ core by exposure in HF solution. Several characterizations, such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and UV visible absorption spectroscopy were used to investigate the prepared nanostructures. The effectiveness of these Au/Ag bimetallic hollow nanospheres as substrates toward surface-enhanced Raman scattering (SERS) detection was evaluated by using rhodamine 6G (R6G) as a probe molecule. We show that such Au/Ag bimetallic hollow nanospheres structure films which consisting of larger interconnected aggregates are highly desirable as SERS substrates in terms of high Raman intensity enhancement. The Au/Ag bimetallic hollow nanostructured aggregate, interconnected nanostructured aggregate and nanoscale roughness are important factors responsible for this large SERS enhancement ability.

Keywords: Au/Ag bimetallic hollow nanospheres; Surface-enhanced Raman scattering; Rhodamine 6G

The synthesis and characterization of Ti/SnO₂–Sb₂O₃/PbO₂ electrodes: The influence of morphology caused by different electrochemical deposition time by Hao An; Qin Li; Dejing Tao; Hao Cui; Xiaotian Xu; Liang Ding; Li Sun; Jianping Zhai (pp. 218-224).

► The Ti/SnO₂–Sb₂O₃/PbO₂ anodes is prepared by anodic deposition under galvanostatic conditions and phenol is taken as the model pollutant to evaluate the electrocatalytic activity. ► Electrochemical deposition time is an important parameters that affects the crystal structure and surface roughness of the metal oxide electrode. ► Electrode surface properties exhibit a direct impact on the electrocatalytic activity, and the best electrocatalytic activity is achieved at the optimal time of 30min. ► At this optimal time, we get the best combination of PbO₂ and the SnO₂–Sb₂O₃ interlayer, which means the optimum combination of the compact and crack-mud structure.For the electrochemical oxidative degradation of wastewater, it is crucial for electrodes to be highly catalytic active, stable in performance and inexpensive in price. This study focuses on the preparation of the Ti/SnO₂–Sb₂O₃/PbO₂ anodes by anodic deposition under galvanostatic conditions and their electrocatalytic activity affected by crystal structure and surface roughness under different electrochemical deposition time, with phenol taken as the model pollutant to evaluate the electrocatalytic activity. The electrode surface morphology is characterized by XRD and SEM-EDX. The treatment effect of phenol is reflected by electrochemical analysis like CV and LSV. An important conclusion from experiment is that electrochemical deposition time has a major impact on electrocatalytic activity with the optimal deposition time observed around 30min. At both deposition time beyond this optimal time window, electrocatalytic activity of phenol is substantially lowered. Increasing in electrochemical deposition time leads to a more uniform and smooth electrode surface, which enjoys a more compact structure than the “cracked-mud” one but lower specific surface area and catalytic activity. On the contrary, the “cracked-mud” structure means potentially a unique porous structure, which makes morphology at 30min a perfect one for high electrocatalytic activity.

Keywords: Phenol; Electrochemical oxidation; Lead dioxide; Surface characterization

Energy barriers for trimethylaluminum reaction with varying surface hydroxyl density by Dae-Hee Kim; Seung-Bin Baek; Yeong-Cheol Kim (pp. 225-229).

Energy variation is shown for TMA reaction to produce a DMA group and CH₄ on the fully OH-terminated a-SiO₂ (001) surface. TMA is less attracted to –OH due to its attraction to a neighboring –OH, compared to the fully OH-terminated Si (001) surface.Display Omitted► Interactions of a trimethylaluminum molecule with varying surface hydroxyl density. ► Four different surfaces with varying surface hydroxyl density. ► Strongly affected energy barriers for TMA reaction with hydroxyl by bond making and bond breaking between them.Energy barriers for trimethylaluminum (TMA) reaction with varying surface hydroxyl (–OH) density were investigated using density functional theory. When the surface –OH density increased from 0 to 6.8/nm² on Si (001) surfaces, the energy barrier for TMA reaction with the surfaces decreased due to attractive interactions between TMA and –OH. When the surface –OH density further increased to 9.2/nm² on a-SiO₂ (001) surfaces, however, the trend was reversed. This was because the attractive interactions between TMA and –OH were decreased due to the attractive interactions of –OH's themselves via hydrogen bond at this high surface –OH density.

Keywords: Atomic layer deposition; Trimethylaluminum; Surface hydroxyl density; Density functional theory

Peptide-induced patterning of gold nanoparticle thin films by Hassan M. Borteh; Nicholas J. Ferrell; Randall T. Butler; Susan V. Olesik; Derek J. Hansford (pp. 230-235).

The use of patterned proteins for the selective deposition and patterning of gold nanoparticles is presented. A comparison of covalently attached proteins with physically adsorbed proteins showed that the covalent attachment provides complete selectivity in the patterning. By controlling the HAuCl₄ concentration and pH of the aqueous solution used in deposition, the gold nanoparticle patterns can provide regions of isolated gold nanoparticles or continuous, dense gold agglomerate patterns. The use of soft lithography lift-off patterning of the proteins makes the entire process non-cleanroom with a previously patterned negative mold. The gold nanoparticle patterns were characterized with SEM, AFM, an electrical probe station, and electron beam induced current (EBIC).Display Omitted► Patterned catalytic peptides using soft lithography lift-off and deposited patterned gold nanoparticles. ► Demonstration patterned deposition of conducting gold nanoparticles using low concentration aqueous solution ► Demonstration of patterned deposition of conducting gold nanoparticle layers using higher concentration of aqueous solution. ► Compared covalently attached proteins with physically adsorbed proteins and peptides for patterned deposition.In this work, the use of patterned proteins and peptides for the deposition of gold nanoparticles on several substrates with different surface chemistries is presented. The patterned biomolecule on the surface acts as a catalyst to precipitate gold nanoparticles from a precursor solution of HAuCl₄ onto the substrate. The peptide patterning on the surfaces was accomplished by physical adsorption or covalent attachment. It was shown that by using covalent attachment with a linker molecule, the influence of the surface properties from the different substrates on the biomolecule adsorption and subsequent nanoparticle deposition could be avoided. By adjusting the reaction conditions such as pH or HAuCl₄ concentration, the sizes and morphologies of deposited gold nanoparticle agglomerates could be controlled. Two biomolecules were used for this experiment, 3XFLAG peptide and bovine serum albumin (BSA). A micro-transfer molding technique was used to pattern the peptides on the substrates, in which a pre-patterned poly(dimethylsiloxane) (PDMS) mold was used to deposit a lift-off pattern of polypropylmethacrylate (PPMA) on the various substrates. The proteins were either physically adsorbed or covalently attached to the substrates, and an aqueous HAuCl₄ solution was applied on the substrates with the protein micropatterns, causing the precipitation of gold nanoparticles onto the patterns. SEM, AFM, and Electron Beam Induced Current (EBIC) were used for characterization.

Keywords: Gold nanoparticles; Patterned deposition; Peptide-induced deposition; Protein attachment; Soft lithography

The effect of surfactants on the magnetic and optical properties of Co-doped SnO₂ nanoparticles by He Jiang; Xiao Fang Liu; Zhi Yu Zou; Zhang Ben Wu; Bo He; Rong Hai Yu (pp. 236-241).

► The ferromagnetism and the orange emission are declined with the increase of surfactant concentration. ► The bound magnetic polaron model is responsible for ferromagnetism, where the carriers are provided by oxygen vacancies. ► The surfactants suppress the formation of oxygen vacancies.A series of Co-doped SnO₂ nanoparticles have been synthesized by the co-precipitation route. Different amounts of surfactant have been used in order to study the effect of surfactants (CTAB) on the magnetic and optical properties. Structural analyses reveal that Co dopants are substituted into rutile SnO₂ nanoparticles without forming any secondary phase. The increase of the surfactant promotes the adsorption of organic molecules on the surfaces of nanoparticles. Meanwhile, both the ferromagnetism and the orange emission drop progressively. The dependence of ferromagnetic properties on the surfactant concentration could be explained based on the bound magnetic polaron, where the carriers are provided by oxygen vacancies. XANES spectra reveal that the electrons transfer from Co 3 d bands to the surfactant ions. Such electron-transfer process suppresses the formation of oxygen vacancies and leads to the decline of the ferromagnetism and optical emission.

Keywords: Surfactant effect; Co-doped SnO; ₂; nanoparticle; Ferromagnetism; Optical emission

Microstructure and mechanical properties of CrN films fabricated by high power pulsed magnetron discharge plasma immersion ion implantation and deposition by Zhongzhen Wu; Xiubo Tian; Zeming Wang; Chunzhi Gong; Shiqin Yang; Cher Ming Tan; Paul K. Chu (pp. 242-246).

► A highly adhered CrN film has been fabricated using a novel PBII&D technique based on high power pulsed magnetron discharge (HPPMS–PIII&D). ► The film exhibits a dense columnar structure and smooth, clean surface without macro-particles. ► The grains in the films have the face-center cubic (fcc) structure with highly (200) preferred orientation. ► The high-voltage pulse has a critical effect on the structure and properties of the prepared coatings for HPPMS–PIII&D.CrN films with strong adhesion with the substrate have been fabricated on Ti6Al4V alloy using novel plasma immersion ion implantation and deposition (PIII&D) based on high power pulsed magnetron sputtering (HPPMS). A macro-particle free chromium plasma is generated by HPPMS while the samples are subjected to high voltage pulses to conduct PIII&D. The CrN coatings have a dense columnar structure and low surface roughness. The grains in the films have the face-center cubic (fcc) structure with the (200) preferred orientation. An excellent adhesion is achieved with a critical load up to 74.7N. An implantation voltage of 18kV yields a hardness of 18GPa and better wear resistance and a low friction coefficient of 0.48 are achieved.

Keywords: PACS; 68.55.Jk; 81.15.CdHigh power pulsed magnetron sputtering; Plasma ion implantation and deposition; High-voltage pulse; CrN

Photocatalytic mineralization study of malachite green on the surface of Mn-doped BiOCl activated by visible light under ambient condition by Brijesh Pare; Bhawna Sarwan; S.B. Jonnalagadda (pp. 247-253).

Degradation of MG on Mn-doped BiOCl was studied in the presence of visible light irradiation. Mechanistic scheme of the effect of Mn doping on BiOCl surface in photocatalytic degradation of MG.Display Omitted► Novel Mn/doped BiOCl catalyst with separate Mn sites was synthesized. ► Reduced crystallite size, larger the specific surface area, provides more exposed area to incident photons. ► The recombination of dissolved chloride ion to the BiOCl photocatalyst ensured BiOCl as a practical photocatalyst with long lifetime. ► Decrease in COD and increase in CO₂ shows complete mineralization.Manganese doped BiOCl has been synthesized by hydrolysis method and characterized by X-ray diffraction (XRD), scanning electron micrographs (SEM) and diffusive reflectance spectra (DRS) methods. Interesting results have been obtained from diffusive reflectance spectra. XRD results show a decrease in the lattice parameter for Mn-doped BiOCl and UV–vis measurement reveals that there is a shift in the optical absorption edge toward higher wavelength, which indicates a decrease in the band gap upon Mn doping. The increased photocatalytic activity in degradation of malachite green dye by Mn-doped BiOCl might be due to increase in life time of photogenerated electrons and holes due to scavenging of electrons by Mn, charging the particle surface due to electron on the surface, which enhances the adsorption of dye molecules, or/and decreased crystallite size. The effect of key operating parameters have also been investigated. Complete mineralization has been confirmed by COD analysis. An assumptive reaction mechanism has also been proposed.

Keywords: BiOCl; Mn doping; Photocatalysis; Mineralization

Development of film sensors based on ZnO nanoparticles for amine gas detection by Huiyun Xia; Taihong Liu; Lining Gao; Luke Yan; Junwen Wu (pp. 254-259).

► A novel ZnO fluorescent film was fabricated by a clean, very easy pathway method. ► The glass slide is the promising substrate for the deposition of ZnO particles. ► There are almost uniformly distributed nano-particles on the surface of the substrates. ► The film is selectively sensitive to the presence of amine and the detection limit for amine gas is calculated 162.0ppm.A novel ZnO fluorescent film has been successfully fabricated by dipping a glass substrate into the N,N-dimethylformamide aqueous solution of Zn(Ac)₂ at low temperature (50°C), then aged for 24h in ZnO colloid dispersion. The morphology, structure, room-temperature photoluminescence (PL) spectra and gas sensing measurement were used to characterize the film. It has been demonstrated that the glass slide is the promising substrate for the deposition of ZnO particles, and there are almost uniformly distributed nano-particles on the surface of the substrates. It has been also revealed that the photo-luminescence emission of the film is selectively sensitive to the presence of amine, a possible explanation from the aspect of the sensing mechanism was proposed. The detection limit for amine vapor is calculated 162.0ppm. Importantly, the response is reversible. Accordingly, it is anticipated that the film may be developed into amine sensor device.

Keywords: ZnO nanoparticles; Amines; Film sensor; Fluorescence

ZnO thin film characterization by X-ray reflectivity optimization using genetic algorithm and Fourier transformation by Ghahraman Solookinejad; Amir Sayid Hassan Rozatian; Mohammad Hossein Habibi (pp. 260-264).

► We applied Parrat's recursive model for constructing theoretical X-ray reflectivity of ZnO thin film. ► Independent information was exploited from Fourier transform of Fresnel reflectivity normalized experimental X-ray reflectivity. ► Optimization was established by constructing the error function describes discrepancy between reflectivities. ► Genetic algorithm optimization yielded structural parameters such as thickness, roughness and EDP of the film.Zinc oxide (ZnO) thin film was fabricated by sol–gel spin coating method on glass substrate. X-ray reflectivity (XRR) and its optimization have been used for characterization and extracting physical parameters of the film. Genetic algorithm (GA) has been applied for this optimization process. The model independent information was needed to establish data analyzing process for X-ray reflectivity before optimization process. Independent information was exploited from Fourier transform of Fresnel reflectivity normalized X-ray reflectivity. This Fourier transformation (Auto Correlation Function) yields thickness of each coated layer on substrate. This information is a keynote for constructing optimization process. Specular X-ray reflectivity optimization yields structural parameters such as thickness, roughness of surface and interface and electron density profile of the film. Acceptable agreement exists between results obtained from Fourier transformation and X-ray reflectivity fitting.

Keywords: X-ray reflectivity; Genetic algorithm; Zinc oxide; Fourier transformation

Preparation of nano/micro-scale column-like topography on PDMS surfaces via vapor deposition: Dependence on volatility solvents by Li Wang; Cunguo Lin; Lihui Yang; Jinwei Zhang; Jiyong Zheng (pp. 265-269).

► We prepared a column-like nano/micro-scale topography on the air plasma oxidized PDMS surfaces as a antifouling material. ► N-heptyl alcohol was mixed into the alkylsiloxane to regulate the scale and roughness of nano/micro-scale topography. ► Difference from dissolving silanes in paraffin oil in former research, TCOS is dissolved in dimethyl-silicone oil here.In this work, a column-like nano/micro-scale topography surface has been prepared via trichloro(octyl)silane (TCOS) vapor deposition on the air plasma oxidized polydimethylsiloxane (PDMSOx) surface. TCOS was mixed into n-heptyl alcohol and dimethyl-silicone oil to form a series of mixture. TCOS could anchor to the PDMSOx surface to form column-like nano/micro-scale topography while n-heptyl alcohol and TCOS volatilized to the PDMSOx surface in the subsequent vapor phase process. These surfaces were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared-attenuated total reflection, contact angle measuring system and atomic force microscopy. It was shown that TCOS had been successfully assembled on the polydimethylsiloxane surface. N-heptyl alcohol mixed into alkylsiloxane could regulate the scale and roughness of column-like nano/micro-scale topography.

Keywords: Topography; AFM; Trichloro(octyl)silane; PDMS; Air plasma; Vapor deposition

Structural and hydrophobic–hydrophilic properties of nanosilica/zirconia alone and with adsorbed PDMS by I.Y. Sulym; M.V. Borysenko; O.V. Goncharuk; K. Terpilowski; D. Sternik; E. Chibowski; V.M. Gun’ko (pp. 270-277).

Hydrophobicity of PDMS/nanooxide nonlinearly depends on PDMS content and grafted zirconia.Display Omitted► Zirconia in the form of nanocrystallites grafted onto nanosilica increases specific surface area. ► Zirconia/nanosilica is more hydrophilic than nanosilica. ► PDMS/zirconia/nanosilica is more hydrophobic than PDMS/nanosilica. ► Hydrophobicity of PDMS/nanooxide depends nonlinearly on PDMS content.Two nanosilica A-300/zirconia (SZ) composites at zirconia contentCZrO2=5 and 20wt.% were synthesized using a wet impregnation method with zirconium acetylacetonate as a precursor. The specific surface area of SZ is larger than that of A-300 because zirconia is composed of nanoparticles (crystallites of 4nm in average size atCZrO2=20wt.%) smaller than those of the initial silica ( d_av≈11nm). A-300 and SZ modified by polydimethylsiloxane (PDMS at molecular weight 1700 and 7960) in amounts of 5, 10, 15, 20 and 40wt.% remained in the powder state with aggregates of primary particles smaller than those of A-300. SZ is more hydrophilic than silica but PDMS/SZ is more hydrophobic (maximum hydrophobic at C_PDMS 15–20 or 40wt.%) than PDMS/A-300.

Keywords: PACS; 61.05.C−; 61.43.Er; 61.43.Gt; 67.30.hp; 68.08.−p; 68.35.bj; 68.43.Pq; 68.47.JnNanosilica; Grafted nanozirconia; Adsorbed PDMS; Structural characteristics; Hydrophilic–hydrophobic properties; Heat of immersion

Structure and surface properties of praseodymium modified alumina by I. Tankov; B. Pawelec; K. Arishtirova; S. Damyanova (pp. 278-284).

.Display Omitted► Well dispersed Pr-oxide species over alumina is observed. ► There is a higher reducibility of supported Pr-oxide species. ► A strong interaction between Pr and Al is detected.Mixed PrO₂–Al₂O₃ oxides with different PrO₂ content (1–20wt.%) were prepared by wetness impregnation of γ-alumina with aqueous solution of praseodymium nitrate. The samples were characterized by different techniques, using surface adsorption–desorption of N₂ ( S_BET), thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), temperature-programmed reduction (TPR) and temperature-programmed desorption of CO₂ (TPD-CO₂). TGA and XRD showed the presence of small praseodymium oxide species on the alumina surface. XPS and DRS detected electron deficient interaction between deposited praseodymium oxide and alumina. It was observed a lower reduction temperature for supported Pr oxide species compared to that of the bulk Pr₆O₁₁. TPD-CO₂ studies suggested that the deposition of Pr oxide on alumina leaded to increase of the basicity of mixed oxides.

Keywords: Mixed PrO; ₂; –Al; ₂; O; ₃; oxides; Physicochemical characterization

Fabrication of superhydrophobic polyaniline films with rapidly switchable wettability by Xiaoyan Zhou; Zhaozhu Zhang; Xuehu Men; Jin Yang; Xianghui Xu; Xiaotao Zhu; Qunji Xue (pp. 285-289).

► We fabricate the superhydrophobic polyaniline film by using a facile one-step spraying method. ► The water contact angle of the superhydrophobic surface reaches to 156°. ► A rapid surface wettability transition between superhydrophobicity and superhydrophilicity can be observed on the polyaniline film.A superhydrophobic polyaniline (PANI) film has been fabricated by using a facile one-step spraying method. The PANI was synthesized via in situ doping polymerization in the presence of perfluorooctanoic acid (PFOA) as the dopant. The water contact angle of this superhydrophobic surface reaches to 156°. Both the surface chemical compositions and morphological structures were analyzed. A granular morphology of PANI with a moderate amount of nanofibers was obtained. Moreover, a rapid surface wettability transition between superhydrophobicity and superhydrophilicity can be observed when it is doped with PFOA and de-doped with base. The mechanism for this tunable wettability has been discussed in detail.

Keywords: Superhydrophobic; Polyaniline; Doping polymerization; Reversible wettability

Surface texturing of the carbon steel AISI 1045 using femtosecond laser in single pulse and scanning regime by J. Stašić; B. Gaković; W. Perrie; K. Watkins; S. Petrović; M. Trtica (pp. 290-296).

► Determined surface damage threshold of the AISI 1045 for ten femtosecond laser pulses, F_th=0.22J/cm². ► Efficient laser cleaning of the surface oxides in single pulse regime. ► Formation of the periodic surface structures approximately in accordance with the laser wavelength.Surface texturing of the metals, including steels, gained a new dimension with the appearance of femtosecond lasers. These laser systems enable highly precise modifications, which are very important for numerous applications of metals. The effects of a Ti:sapphire femtosecond laser with the pulse duration of 160fs, operating at 775nm wavelength and in two operational regimes – single pulse (SP) and scanning regime, on a high quality AISI 1045 carbon steel were studied. The estimated surface damage threshold was 0.22J/cm² (SP). Surface modification was studied for the laser fluences of 0.66, 1.48 and 2.37J/cm². The fluence of 0.66J/cm², in both working regimes, induced texturing of the material, i.e. formation of periodic surface structures (PSS). Their periodicity was in accordance with the used laser wavelength. Finally, changes in the surface oxygen content caused by ultrashort laser pulses were recorded.

Keywords: Steel; Femtosecond laser; Laser processing; Periodic surface structures

The structure and mechanical properties of thick rutile–TiO₂ films using different coating treatments by Li-Chin Chuang; Chin-Hsiang Luo; Shin-hao Yang (pp. 297-303).

► Rutile–TiO₂ nanopowders were prepared using a modified homogeneous-precipitation process at low temperature. ► Thick TiO₂ films were formed by natural air-drying, water-vapor exposure, and calcination treatments, respectively. ► Mechanical properties, including refractive index, hardness and Young's modulus, of the pretreated films were determined and compared with related surface morphology.The hardness and Young's modulus of thick rutile–TiO₂ films were determined using a continuous stiffness measurement (CSM) technique in this study. Pure rutile–TiO₂ nanopowders (TH2O,TFeSO4 andTCuSO4) were prepared using a modified homogeneous-precipitation process at low temperature (MHPPLT) method. The TiO₂ films were prepared from sols using 3% (w/w) of the prepared-TiO₂ suspension solution coated onto silicon wafers. After dip-coating was completed, the coatings were further treated by natural air-drying, water-vapor exposure, and calcination, respectively. An ellipsometry with a monochromator was used to measure the thickness and refractive index of the TiO₂ films, and a scanning electron microscopy (SEM) to determine their morphology. Three coatings ofTH2O,TFeSO4 andTCuSO4 demonstrated their refractive indexes of around 1.60 under three treatments. Volumetric expansion and thickness of the coatings should influence their refractive index. Furthermore, the continuous stiffness measurement (CSM) technique was used to perform nanoindentation testing on the hardness and Young's modulus of prepared rutile–TiO₂ coatings. The mean hardness and Young's modulus of three coatings increased with preparation temperature. In addition, theTH2O coatings demonstrated greater hardness and modulus than those ofTFeSO4 andTCuSO4 coatings in the natural air-drying condition. Surface cracking observed on the calcinatedTFeSO4 should be the reason why an obvious decrease of the mean hardness and Young's modulus appeared. Finally, two mechanical properties and related nanoindentation depth of the coatings were discussed in detail.

Keywords: Nanoindentation; Continuous stiffness measurement; Mechanical properties; Thick films; Rutile; TiO; ₂

Radio frequency plasma enhanced chemical vapor based ZnO thin film deposition on glass substrate: A novel approach towards antibacterial agent by Jagannath Panigrahi; Debadhyan Behera; Ipsita Mohanty; Umakanta Subudhi; Bijan B. Nayak; Bhabani S. Acharya (pp. 304-311).

► ZnO thin films are synthesized on borosilicate glass slides by PECVD method. ► The films are annealed at 450°C in air for 1.5h to improve crystallinity. ► The films exhibit excellent inhibition effect against E. coli and P. aeruginosa. ► The bactericidal activity is explained on the basis of diffusion of Zn²⁺ ions into bacteria cells.In the present study, the structural, optical and antibacterial properties of ZnO thin films are reported. ZnO thin films are deposited on borosilicate glass substrates by radio frequency plasma enhanced chemical vapor deposition (PECVD) using oxygen as process gas. The crystallinity of the deposited films is improved upon annealing at 450°C in air for 1.5h and the polycrystalline nature of the films is further confirmed by selected area electron diffraction. The particle size of the annealed film (thickness 476nm) is found to be ∼34nm from the transmission electron microscopic observation. Energy dispersive X-ray spectrum indicates the stoichiometric deposition of ZnO films. The films are highly transparent (transmittance >85%) in the visible region of electromagnetic spectrum. The films exhibit excellent antibacterial effect towards the growth of Escherichia coli and Pseudomonas aeruginosa.

Keywords: Zinc oxide; Chemical vapour deposition; Antibacterial property; Electron microscopy

Mechanical and electrochemical characterization of vanadium nitride (VN) thin films by J.C. Caicedo; G. Zambrano; W. Aperador; L. Escobar-Alarcon; E. Camps (pp. 312-320).

► We present a superficial phenomenon that occurs in surface of single layer thin films. ► Our paper exhibits a novel and innovative binary system (V–N). ► We show an improvement on surface mechanical properties and response to surface corrosion attack. ► We present that V–N films offer protection to the industrial steel surface.Vanadium nitride (V–N) thin films were grown using a reactive d.c. magnetron sputtering process, from a vanadium target (99.999%) in an Ar/N₂ gas mixture at different deposition bias voltage. Films were deposited onto silicon (100) and RUS-3 steel substrates at 400°C. Structural, compositional, mechanical and electrochemical characterizations were performed by X-ray diffraction (XRD), elastic forward analysis (EFA), nanoindentation, electrochemical impedance spectroscopy (EIS), and Tafel polarization curves, respectively. X-ray diffraction patterns show the presence of (111) and (200) crystallographic orientations associated to the V–N cubic phase. Nanoindentation measurements revealed that when the bias voltage increases from 0V to −150V the hardness and elastic modulus are increased from 11GPa to 20GPa and from 187GPa to 221GPa, respectively. EIS and Tafel curves showed that the corrosion rate of steel, coated with V–N single layer films deposited without bias voltage, diminishes 90% compared to the steel without this coating. On the other hand, when the V–N coating was deposited at the highest d.c. bias voltage (−150V), the corrosion rate was greater than in the steel coated with zero-voltage (0V) V–N films. This last result could be attributed to the formation of porosities produced by the ion bombardment during the deposition process.

Keywords: Vanadium nitride; Magnetron sputtering; Hard films; Electrochemical impedance spectroscopy; Mechanical properties

Investigation of the fill factor of dye-sensitized solar cell based on ZnO nanowire arrays by Yongshu Tian; Chenguo Hu; Qing Wu; Xiaohui Wu; Xiaoyan Li; Muhammad Hashim (pp. 321-326).

Display Omitted► Fill factor of DSCs is demonstrated not simply affected by charge recombination. ► Low electron injection efficiency of ZnO nanowires is ascribed to the repellence of radial electric field. ► Low electron injection efficiency of ZnO nanowires is also ascribed to dye adsorption nature. ► Fill factor of ZnO nanowire cell can be improved by coating the nanowires with some oxides.The fill factor of dye-sensitized solar cells based on the ZnO nanowire array is very low, which is usually ascribed to a rapid charge recombination. In this article, the influence on the fill factor of ZnO nanowire array cell is investigated and discussed by comparing dark current and decay rate of open circuit potential of the ZnO nanowire array cell with those of the ZnO nanoparticle cell, TiO₂ nanoparticle cell and TiO₂-coated ZnO nanowire array cell. The results demonstrate that the low fill factor of the ZnO nanowire array cell is largely caused by a rapid decrease of electron injection efficiency rather than a rapid charge recombination, which is decided by the absorption nature of Ru-complexed dye molecules on ZnO surface and repellency of radial electric field. The fill factor of the ZnO nanowire array cell can be improved by coating ZnO nanowires with a wide band gap semiconductor material or metal oxide insulator.

Keywords: Dye-sensitized solar cell; Fill factor; Electron injection efficiency

Characterization of scandia doped pressed cathode fabricated by spray drying method by Yuntao Cui; Jinshu Wang; Wei Liu; Yiman Wang; Meiling Zhou (pp. 327-332).

► Scandia doped pressed cathode has been prepared in a simple fabrication process via spray drying method. ► This SDP cathode exhibits good emission property. ► The evaporation rate of SDP cathode is lower than those of the Ba–W and M-type cathodes.Scandia doped pressed cathode was prepared by a new method of spray drying combined with two-step hydrogen reduction process. The Sc₂O₃ and barium–calcium aluminate co-doped powders have sub-micrometer size in the range of 0.1–1μm and scandium oxide and barium–calcium aluminate are distributed evenly in the powders. The cathodes sintered by powder metallurgy at 1600°C_b have a smooth surface and sub-micrometer grain structure with homogeneous distribution of scandium, barium, calcium and aluminum which are dispersed over and among the tungsten grains. This cathode has good emission, e.g., the current density of this cathode reaches 31.50A/cm² at 850°C_b. After proper activation, the cathode surface is covered by a Ba–Sc–O active substances layer with a preferable atomic ratio, leading to its good emission property. The evaporation activation energy of SDP cathode with 4.58eV is the highest among the Ba–W, M-type and SDP cathodes, and the average evaporation velocity v_t of SDP cathode with 1.28×10⁻⁸gcm⁻²s⁻¹ at 1150°C_b is the lowest one.

Keywords: Thermionic emission; Scandate cathode; Tungsten; Evaporation

Growth and electron field emission of ZnO nanorods on diamond films by Dandan Sang; Hongdong Li; Shaoheng Cheng (pp. 333-336).

► The growth evolution of ZnO nanorods (NRs) on diamond films has been investigated. ► The size of diamond grains determines a certain extent the diameter of the ZnO NRs. ► The mechanism for the influence of diamond grain size on the features of ZnO NRs has been studied. ► The electron field emission properties of the ZnO NRs/diamond system have been significantly improved with respect to pure diamond film.Zinc oxide (ZnO) nanorods grown on chemical vapor deposited diamond films by thermal vapor transport method have been investigated. In the initial growth status, the semi-spherical ZnO nuclei were preferably deposited near the growth steps on the terraces and the boundaries of diamond grains. With increasing the growth time, the [0001] orientated ZnO nanorods appeared and further covered the whole diamond film. It is found that the size of diamond grains would determine the diameter of ZnO nanorods. The electron field emission properties of the ZnO nanorods/diamond system have been significantly improved with respect to pure diamond film. The feature of the ZnO nanorods grown on diamond films played an important role in further enhancing the electron field emission performances.

Keywords: ZnO nanorods; Diamond films; Growth evolution; Electron field emission

Organosilane modified silica/polydimethylsiloxane mixed matrix membranes for enhanced propylene/nitrogen separation by Arnel B. Beltran; Grace M. Nisola; Eulsaeng Cho; Erli Eros D. Lee; Wook-Jin Chung (pp. 337-345).

► Two types of chlorosilanes were successfully incorporated on fumed SiO₂ surface via silanization. ► FTIR spectroscopy and elemental analysis confirmed the surface modification of SiO₂. ► Defect-free composite PDMS films were produced with surface-modified SiO₂ as fillers. ► PDMS membranes with surface-modified SiO₂ exhibited enhanced C₃H₆/N₂ permselectivities.Gas transport behaviors of oxygen (O₂), nitrogen (N₂) and propylene (C₃H₆) in polydimethylsiloxane (PDMS) mixed matrix membranes (MMM) containing modified silica (SiO₂) nanoparticles are presented. Two surface modified SiO₂ nanoparticles, silica dimethyloctyl silane (Si-DMOS) and silica dimethylphenyl silane (Si-DMPS), were used as fillers. Surface modification was carried out through silanization, which was confirmed via Fourier transform infrared spectroscopy. From elemental analysis, degrees of modifications on Si-DMOS and Si-DMPS were estimated to be 29.64% and 79.89%, respectively. Field emission scanning electron microscopy showed uniform distribution of the modified SiO₂ fillers in MMMs. Both MMMs exhibited reduced O₂ and N₂ permeabilities as compared to pure PDMS, while enhanced C₃H₆ permeabilities were observed. Consequently, C₃H₆/N₂ permselectivities were increased by 35 and 44% in MMMs filled with Si-DMOS and Si-DMPS, respectively. Results revealed that permeability was dependent on penetrant diffusivities, a parameter related to the structure of MMMs. Density measurements and differential scanning calorimetry were performed to elucidate the changes in MMM properties which affected the permeation behaviors of O₂, N₂ and C₃H₆. Overall, both Si-DMOS and Si-DMPS show potential as fillers for the enhancement of PDMS permeation performance.

Keywords: Silica nanoparticle; Surface modification; Silanization; Mixed matrix membrane; Gas separation; Propylene

Electroluminescence with micro-watt output from ultra-small sized Si quantum dots/amorphous SiO₂ multilayers prepared by laser crystallization method by W. Xu; H.C. Sun; J. Xu; W. Li; W.W. Mu; Y. Liu; M.Y. Yan; X.F. Huang; K.J. Chen (pp. 346-349).

► Si QDs-based multilayers with ultra-small size (1.8nm and 3.2nm) are obtained by laser crystallization method. ► EL spectrum is dependent of the dot size and contains two sub-bands which are originated from the different mechanism. ► The emission efficiency is improved by controlling the dot size as small as 1.8nm and μ-watt light emission is obtained.We report the fabrication of Si quantum dots (QDs)/SiO₂ multilayers by using KrF excimer laser (248nm) crystallization of amorphous Si/SiO₂ multilayered structures on ITO coated glass substrates. Raman spectra and transmission electron microscopy demonstrate the formation of Si QDs and the size can be controlled as small as 1.8nm. After laser crystallization, Al electrode is evaporated to obtain light emitting devices and the room temperature electroluminescence (EL) can be detected with applying the DC voltage above 8V on the top gate electrode. The luminescent intensity increases with increasing the applied voltage and the micro-watt light output is achieved. The EL behaviors for samples with different Si dot sizes are studied and it is found that the corresponding external quantum efficiency is significantly enhanced in sample with ultra-small sized Si QDs.

Keywords: Laser crystallization; Electroluminescence; Si quantum dots

X-ray photoelectron spectroscopy analysis of (Ln1−_xSr_x)CoO3−_δ (Ln: Pr, Nd and Sm) by Jung Hyun Kim (pp. 350-355).

► Sr and various lanthanide elements doped complex perovskites electrodes. ► Merged oxygen peaks of Ln1−_xSr_xCoO3−_δ and generation of more oxygen vacancies on the surface of electrodes as a function of Sr and lanthanide concentration. ► Enhancement of the binding energy in Sr spectra by the substitution of Sr into the A-site of a perovskite. ► The partial existence of Co⁴⁺ to provide small polaron hopping by electrons, maintaining charge neutrality and providing electronic conduction.The chemical states of the surface of (Ln_0.5Sr_0.5)CoO3−_δ (Ln (lanthanides)=Pr, Nd and Sm) used for cathode materials of intermediate temperature operating solid oxide fuel cells (IT-SOFCs) were investigated by X-ray photoelectron spectroscopy (XPS). Oxygen peaks comprised of lower binding energy (LBE) and higher binding energy (HBE) peaks from (Ln_0.5Sr_0.5)CoO3−_δ and Pr_0.3Sr_0.7CoO3−_δ (PSC37) showed that some merged oxygen peak behavior is a function of the Sr and lanthanide concentrations. By investigating the oxygen peaks, it was determined that more oxygen vacancies were generated on the surface of the cathodes when the lanthanides and Sr were substituted into perovskite oxides. When comparing the binding energies (BEs) of PSC37 with Pr_0.5Sr_0.5CoO3−_δ (PSC55), the LBE and HBE of the Sr peaks both increased when Sr was substituted at the A-site of a perovskite. Surface analysis of the Co peak on the surface of the cathode materials showed that the Co exists mainly as Co³⁺ and partially oxidized to Co⁴⁺ on the cathode materials. The partial existence of Co⁴⁺ can provide some polaron hopping providing electronic conduction for the solid oxide fuel cell.

Keywords: X-ray photoelectron spectroscopy (XPS); Intermediate temperature operating solid oxide fuel cell (IT-SOFC); Cathode; Binding energy; Lanthanide (Ln)

Effect of gas flow ratio on the microstructure and mechanical properties of boron phosphide films prepared by reactive magnetron sputtering by Z.C. Jia; J.Q. Zhu; C.Z. Jiang; W.X. Shen; J.C. Han; R.R. Chen (pp. 356-360).

► Boron phosphide films with cubic phase are obtained using radio frequency reactive magnetron sputtering technique at low temperature. ► The variation laws of microstructure and mechanical properties with the gas flow ratio increasing by RFRMS technique have been investigated. ► The results indicate that the BP film prepared at low gas flow ratio of 3/50 is optimal.Boron phosphide films were grown on silicon substrate by radio frequency reactive magnetron sputtering using boron target and hydrogen phosphine at different gas flow ratios (PH₃/Ar) at lower temperature. The chemical composition, microstructure and mechanical properties were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectrum, FTIR spectrum, surface profilometer and nano-indenter. The results indicate that the atomic ratio (P/B) rises from 1.06 up to 1.52 with the gas flow ratio increasing from 3/50 to 15/50. Simultaneously, the hardness and Young's modulus decrease from 25.4GPa to 22.5GPa, and 250.4GPa to 238.4GPa, respectively. Microstructure transforms from microcrystalline state to amorphous state along with the gas flow ratio increasing. Furthermore higher gas flow ratio leads to lower stress. The BP film prepared at the gas flow ratio of 3/50 can be contributed with the best properties.

Keywords: Reactive magnetron sputtering; Boron phosphide films; Microstructure; Mechanical properties

Adsorption of bovine serum albumin on amorphous carbon surfaces studied with dip pen nanolithography by Pradeep K. Yadav; Fiona McKavanagh; Paul D. Maguire; Patrick Lemoine (pp. 361-369).

► We studied BSA protein adsorption on two amorphous carbons; taC and a-C:H:Si. ► We used the DPN technique, contact angle measurements and AFM force curves. ► Drop volume study showed a line tension effect. ► The data consistently shows that BSA diffuses more readily on a-C:H:Si. ► The limitations of DPN as a lithographic tool were outlined.This article reports the use of dip pen nanolithography (DPN) for the study of adsorption of bovine serum albumin (BSA) proteins on amorphous carbon surfaces; tetrahedral amorphous carbon (t-aC) and silicon doped hydrogenated amorphous carbon (a-C:H:Si). Contact angle study shows that the BSA proteins reduce the contact angle on both carbon materials. We also noticed that the drop volume dependence is consistent with a negative line tension, i.e. due to an attractive protein/surface interaction. The DPN technique was used to write short-spaced (100nm) BSA line patterns on both samples. We found a line merging effect, stronger in the case of the a-C:H:Si material. We discuss possible contributions from tip blunting, scratching, cross-talk between lever torsion and bending and nano-shaving of the patterns. We conclude that the observed effect is caused in large measure by the diffusion of BSA proteins on the amorphous carbon surfaces. This interpretation of the result is consistent with the contact angle data and AFM force curve analysis indicating larger tip/surface adhesion and spreading for the a-C:H:Si material. We conclude by discussing the advantages and limitations of DPN lithography to study biomolecular adsorption in nanoscale wetting environments.

Keywords: DPN; BSA; Contact angle; LFM

Ti–Cu–N hard nanocomposite films prepared by pulse biased arc ion plating by Yanhui Zhao; Xueqi Wang; Jinquan Xiao; Baohai Yu; Fengqi Li (pp. 370-376).

► Ti–Cu–N nanocomposite films were deposited by pulse biased arc ion plating. ► The Cu content depended on the pulse bias voltage. ► The maximum value of hardness reaches 31.5GPa at −600V, with Cu content of 1.75at.%. ► The maximum value of adhesion of the film with 74N was obtained at pulse bias −900V.In this work, Ti–Cu–N hard nanocomposite films were deposited on high-speed-steel (HSS) substrates using a TiCu (88:12at.%) single multi-component target by pulse biased arc ion plating. The influence of pulse bias voltages was examined with regard to elemental composition, structure, morphology and mechanical properties of the films. The Cu atomic content of Ti–Cu–N films was determined by Electron Probe Micro-Analyzer (EPMA). The structure and morphology were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Hardness and film/substrate adhesion were determined by nanoindenter and scratch test, respectively. The results showed that the content of Cu appeared to be in the range of 1.75–4.5at.%, depending on pulse bias voltages. The films exhibit a preferred orientation TiN (111) texture when the substrate bias voltages were −100V and −300V, while the preferred orientation change to be a preferred orientation TiN (220) one when the substrate bias voltages increase to −600V and −900V. And no obvious sign of metal copper phase was observed. The SEM morphologies showed some macroparticles (MPs) on the surface of the films and the relative content of the MPs decreased significantly when the substrate bias voltages increased from −100 to −900V. The maximum value (74N) of the film/substrate adhesion of the films was obtained when the substrate bias voltage was −600V with Cu content of 1.75at.%. Hardness enhancement was observed, the value of the hardness increased firstly and reached a maximum value of 31.5GPa, corresponding to Cu content of 1.75at.%, and then it decreased when the substrate bias voltage changed from −100 to −900V. The hardness enhancement was discussed related to the concept for the design of hard materials.

Keywords: Pulse biased arc ion plating; Nanocomposite films; Ti–Cu–N; Hardness

Molecule oxygen-driven shaping of gold islands under thermal annealing by Cunji Yan; Yongchong Chen; Aizi Jin; Ming Wang; Xiangdong Kong; Xifeng Zhang; Yu Ju; Li Han (pp. 377-381).

Display Omitted► We investigate the annealing of Au film in different thermal environments. ► The role played by O₂ in the morphology evolution of Au film under annealing is generally ignored in literature. ► It is experimentally found that O₂ drives the migration of Au atoms under thermal treatments. ► The shapes of Au islands formed by annealing are related with the interaction between O₂ and the Au surface.Fabrication of the gold micro/nano-structure in a controlled manner has recently attracted considerable interest for its potential applications. With the help of the AFM and XRD measurements, our research on the annealing of the evaporated thin gold films under different thermal environments reveals that O₂ molecule, of which the influence has been generally ignored in the prevenient literatures, can play a very important role in the formation of gold island film. It is experimentally found that the molecule oxygen-driven migration of gold atoms can only occur at a high enough temperature. The time-dependent morphological development of the thin gold film annealing in O₂ is also observed, which is determined by the reduction of the whole interface energy. The morphological features of the Au islands, such as the flat top surfaces and the steep edges, point to the essential role of the interaction between oxygen and the specifically oriented gold surface during the structural evolution.

Keywords: Thin gold film; Thermal treatment; Oxygen; Gold island structure

Abrasive resistance of arc sprayed carbonitride alloying self-shielded coatings by Yu Deng; Shengfu Yu; Shule Xing; Linbing Huang; Yan Lu (pp. 382-387).

► C, N and some microalloy elements in flux-cored wire form hard particles. ► Good wear-resistant arc sprayed coatings can be prepared with the optimized process parameters. ► Wear-resistant mechanism of the coatings was explained. ► Coatings made by the carbonitride alloying self-shielded wire have better comprehensive properties.Wear-resistant coatings were prepared on the surface of the Q235 low-carbon steel plate by HVAS with the carbonitride alloying self-shielded flux-cored wire. Detection and analysis on the microstructure and properties of the coatings were carried out by using scanning electron microscope, microhardness tester and wear tester. The forming, the wear resistance and its mechanism of the coatings were studied. The results show that the coatings have good forming, homogeneous microstructure and compact structure. The coatings have good hardness, the average microhardness value reaches 520HV_0.1, and the highest value is up to about 560HV_0.1. As a result, the coatings have good abrasive wear performance and adhesion strength.

Keywords: Carbonitride alloying; Self-shielded flux-cored wire; High velocity arc spraying (HVAS); Abrasive wear

Surface wettability of atmospheric dielectric barrier discharge processed Armos fibers by Caixia Jia; Ping Chen; Qian Wang; Bin Li; Mingxin Chen (pp. 388-393).

► The atmospheric DBD plasma had great influence on Armos fiber surface wettability. ► Appropriate exposure time increased the oxygen content and surface roughness greatly. ► The improvement of fiber surface polarity and roughness aided good wetting. ► Single fiber tensile strength was little affected with the wettability enhancement. ► After longer exposure to the plasma, the fiber surface free energy decreased.Wettability of Armos fibers has been investigated after exposed to dielectric barrier discharge (DBD) plasma, which was performed at atmospheric pressure in air while varying the sample treatment time between 9 and 27s. Contact angles and surface free energy of the original and plasma-treated fibers were measured with dynamic contact angle analysis (DCAA) to reveal the correlation between the fiber wettability and the surface treatment, including surface composition and topography modifications, which were evaluated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), respectively. It was found by XPS analysis that the O/C atomic ratio on Armos fiber surface can be increased from 0.134 to 0.248 after the 18s exposure to the plasma and many polar functional groups were proved to be incorporated into the surface, which aided good wetting. In addition, AFM observations revealed the changes of fiber surface microstructure, showing significant enhancement of the surface roughness after the treatment, which could also bring the fiber better wettability. What's more, the impacts of fiber surface treatment on its tensile properties were characterized by single fiber tensile strength (SFTS) testing. Results showed that Armos fibers exhibited only slight reductions in their tensile strengths with the great enhancement in fiber surface free energy.

Keywords: Wettability; Surface free energy; Armos fibers; DBD plasma; Tensile strength

Confocal Raman spectromicroscopy for tin-core/carbon-shell nanowire heterostructure by Fengping Wang; Ruying Li; Xueliang Sun; Zhifeng Ding (pp. 394-398).

► Heterostructures of CNTs encapsulated tin nanowires have been characterized. ► The Raman spectra manifest the existence of nano-graphite in amorphous carbon walls. ► The Raman image reproduces the pristine heterostructures of the CNTs as seen in SEM. ► The resultant heterostructures are luminescent. ► The luminescence was attributed to nano-graphite embedded in the amorphous carbon.High density heterostructures of carbon nanotubes encapsulated single crystalline tin nanowires have been characterized by Raman spectromicroscopy. The morphology, composition and structure of the synthesized nanoheterostructures were examined by using scanning electron microscopy, transmission electron microscopy. The Raman spectra obviously manifest the crystalline nano-graphite within amorphous carbon walls in the heterostructures. The Raman image reproduces the pristine heterostructures of the CNTs as seen in SEM image, which illustrate the single nanowires oriented uniformly grown on micro-graphitic fibers. It was found that the resultant heterostructures are luminescent which was attributed to crystalline nano-graphite embedded in the amorphous carbon matrix, which is a consequence of excitons localization within an increasing number of sp² rich clusters. The contrast in the Raman image reflects nonuniform distribution of the graphite cluster size which acts as the radiative centers. The luminescent property was reviewed. The enhanced Raman spectra and luminescent property by the well-defined tin nanowires inside the heterostructures was revealed.

Keywords: Nanoheterostructure; Raman spectromicroscopy; Nano-crystalline graphite; Luminescence

Structural and mechanical properties of multi-element (TiVCrZrHf)N coatings by reactive magnetron sputtering by Shih-Chang Liang; Du-Cheng Tsai; Zue-Chin Chang; Huan-Shin Sung; Yi-Chen Lin; Yi-Jung Yeh; Min-Jen Deng; Fuh-Sheng Shieu (pp. 399-403).

► The N₂ flow influences the structure and properties of (TiVCrZrHf)N coatings. ► The saturated nitride coatings reveal a columnar structure with FCC crystal phase. ► The coatings without external heating or bias can achieve a high hardness of 23.8GPa.In this study, (TiVCrZrHf)N multi-component coatings with quinary metallic elements were deposited by reactive magnetron sputtering system. The composition, structure, and mechanical properties of the coatings deposited at different N₂ flow rates were investigated. The (TiVCrZrHf)N coatings deposited at N₂ flow rates of 0, 1, and 2SCCM showed an amorphous structure, whereas those deposited at N₂ flow rates of 4 and 6SCCM showed a simple face-centered cubic solid solution structure. A saturated nitride coating was obtained for N₂ flow of 4SCCM and higher. By increasing N₂ flow to 4SCCM, the hardness and modulus reached a maximum value of 23.8±0.8 and 267.3±4.0GPa, respectively.

Keywords: Hard coatings; Multi-element nitride; Structure; Hardness

Effect of Cr100−_xTi_x ( x=0–19at.%) alloy underlayers on the high coercivity of FePt thin film below the substrate temperature of 250°C by S.H. Lee; S.H. Eun (pp. 404-407).

► Ordering process temperature of FePt films was reduced below 250°C by CrTi underlayer. ► In-plane coercivity of FePt films is highly maintained to 6000Oe at 250°C by CrTi underlayer. ► CrTi underlayer is beneficial in view of a cost comparing to other metal underlayers.The effect of Cr100−_xTi_x underlayer on orderd- L1₀ FePt films was investigated. A low-temperature ordering of FePt films could be attained through changing the Ti content of Cr100−_xTi_x underlayer. The ordering temperature of the 30nm FePt film grown on 20nm Cr₉₀Ti₁₀ underlayer was reduced to 250°C which is practical manufacture process temperature. An in-plane coercivity was very high to 6000Oe and a ratio of remnant magnetization ( M_r) to saturation magnetization ( M_s) was as large as 0.85. This result indicates that the coercivity obtained at 250°C by the effect of CrTi underlayer is significantly higher than those obtained at 250–275°C by the effect of underlayers in other conventional studies. The prominent improvement of the magnetic properties of ordered FePt thin films at low temperature of 250°C could be understood with considering the strain-induced ordering phase transformation associated with lattice mismatch between Cr underlayer and FePt magnetic layer due to an addition of Ti content.

Keywords: FePt alloys; Magnetic thin films; CrTi underlayer; Low-temperature ordering; Coercivity

Adsorption and dissociation of O₂ on CuCl(111) surface: A density functional theory study by Riguang Zhang; Hongyan Liu; Baojun Wang; Jun Ren; Zhong Li (pp. 408-413).

Display Omitted► Molecular O₂ lying flatly on CuCl(111) surface is the stable configuration. ► Upon O₂ adsorption, oxygen species show the characteristic of the superoxo. ► O₂ dissociation into atomic O needs to overcome a large activation barrier. ► The superoxo mainly contributes to improving the catalytic activity of CuCl.The adsorption and dissociation of O₂ on CuCl(111) surface have been systematically studied by the density functional theory (DFT) slab calculations. Different kinds of possible modes of atomic O and molecular O₂ adsorbed on CuCl(111) surface and possible dissociation pathways are identified, and the optimized geometry, adsorption energy, vibrational frequency and Mulliken charge are obtained. The calculated results show that the favorable adsorption occurs at hollow site for O atom, and molecular O₂ lying flatly on the surface with one O atom binding with top Cu atom is the most stable adsorption configuration. The O–O stretching vibrational frequencies are significantly red-shifted, and the charges transferred from CuCl to oxygen. Upon O₂ adsorption, the oxygen species adsorbed on CuCl(111) surface mainly shows the characteristic of the superoxo (O₂⁻), which primarily contributes to improving the catalytic activity of CuCl, meanwhile, a small quantity of O₂ dissociation into atomic O also occur, which need to overcome very large activation barrier. Our results can provide some microscopic information for the catalytic mechanism of DMC synthesis over CuCl catalyst from oxidative carbonylation of methanol.

Keywords: Oxygen; CuCl(1; 1; 1); Adsorption; Dissociation; Density functional theory

Synthesis and photochromic properties of 1,3-diaminopropane-induced MoO₃ powder by Yi Shen; Rong Huang; Yang Li; Shuzhen Yao (pp. 414-418).

► MoO₃ powders are successfully synthesized via a facile chemical method. ► Well-dispersed MoO₃ rods are formed when 1,3-diaminopropane (DAP) added. ► Light absorption capacity of DAP-induced MoO₃ is improved due to large surface area. ► DAP-induced MoO₃ shows better photochromic properties than the non-induced one.In the present work, molybdenum trioxide (MoO₃) powder with novel morphology and good photochromic properties was successfully synthesized via a facile chemical method. The capping agent 1,3-diaminopropane (DAP) was found to be vital in the formation of the morphology, as well as the good photochromism of MoO₃. The as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), N₂ adsorption–desorption analysis (BET) and ultraviolet and visible spectroscopy (UV–vis).

Keywords: MoO; ₃; powder; 1,3-diaminopropane; Photochromism

Electrical characteristics of insulating aluminum nitride MIS nanostructures by Bassam Abdallah; Sameer Al-Khawaja; Anas Alkhawwam (pp. 419-424).

► We study the insulating properties of high-quality aluminum nitride thin films. ► The films exhibited (002) preferential orientation and were prepared as MIS. ► The dielectric constant has been found to depend on texture and thickness of films. ► Trapped charges at interface were estimated to be of the order of 10¹⁰cm⁻²eV⁻¹.Capacitance–voltage measurements of high quality PECVD and MBE grown aluminum nitride (AlN) thin films have been performed. The prepared films have shown polycrystalline (002)-preferential orientation, and were deposited on p-type Si (100) substrates with Pt forming the metal gate in a metal–insulator–semiconductor (MIS) configuration. The structure, crystallinity, texture and insulating properties have been found to depend on film thickness and were substantially influenced by the increase of the thickness. C– V measurements of the epitaxial and PECVD films were carried out and their insulating characteristics with increasing thickness (200–1000nm) were investigated. The epitaxial films exhibited no hysteresis in capacitance behaviour, owing to better crystalline quality over the PECVD grown ones. Capacitance curves versus bias voltage have also been acquired at different temperatures; 10K, 30K and 50K for deposited polycrystalline AlN films of (002) orientation. We have found that the defects trapped in the Pt/AlN/Si structure played a key role in dominating the overall behaviour of the C– V measurement curves. The trapped charges at the interface between the AlN insulating film and Si substrate caused the capacitance characteristics to shift to negative voltages, and the estimated charge density was of the order of 10¹⁰ and 10⁸cm⁻²eV⁻¹ for the PECVD and epitaxial samples respectively. The I– V measurements referred to space-charge conduction mechanism, and the deduced leakage current was found to be of the order of 10⁻⁹A at 200nm film thickness.

Keywords: Aluminum nitride; MIS structure; Trapped charges; Dielectric constant

Biocompatibility of polypropylene non-woven fabric membrane via UV-induced graft polymerization of 2-acrylamido-2-methylpropane sulfonic acid by Lingjie Song; Jie Zhao; Huawei Yang; Jing Jin; Xiaomeng Li; Paola Stagnaro; Jinghua Yin (pp. 425-430).

► The grafting of sulfonic-based polymer (poly(AMPS)) on polypropylene non-woven fabric (NWF PP) membrane surface. ► Surface grafting on NWF PP membrane via O₂ plasma pretreatment combining with UV-irradiated technique. ► Obviously enhanced resistance to static protein adsorption and platelet adhesion was acquired by the modified NWF PP membrane.This work described the graft polymerization of a sulfonic acid terminated monomer, 2-acrylamido-2-methylpropane sulfonic acid (AMPS), onto the surface of polypropylene non-woven (NWF PP) membrane by O₂ plasma pretreatment and UV-induced photografting method. The chemical structure and composition of the modified surfaces were analyzed by FTIR-ATR and XPS, respectively. The wettability was investigated by water contact angle and equilibrium water adsorption. And the biocompatibility of the modified NWF PP membranes was evaluated by protein adsorption and platelet adhesion. It was found that the graft density increased with prolonging UV irradiation time and increasing AMPS concentration; the water contact angles of the membranes decreased from 124° to 26° with the increasing grafting density of poly(AMPS) from 0 to 884.2μgcm⁻², while the equilibrium water adsorption raised from 5wt% to 75wt%; the protein absorption was effectively suppressed with the introduction of poly(AMPS) even at the low grafting density (132.4μgcm⁻²); the number of platelets adhering to the modified membrane was dramatically reduced when compared with that on its virgin surface. These results indicated that surface modification of NWF PP membrane with AMPS was a facile approach to construct biocompatible surface.

Keywords: Biocompatibility; 2-Acrylamido-2-methylpropane sulfonic acid (AMPS); UV-induced graft polymerization; Polypropylene non-woven fabric membrane

Physico-chemical properties of titania nanotubes synthesized via hydrothermal and annealing treatment by Leo Bey Fen; Tan Kim Han; Ng Meng Nee; Bee Chin Ang; Mohd Rafie Johan (pp. 431-435).

► Limited literature is available on the effects of annealing treatments on the physic-chemical properties of titania nanotubes (TNTs). Hence, this work is focused on the synthesis of titania nanotubes via hydrothermal and annealing routes. ► Annealing treatment does not damage the tubular structure of the samples. ► The crystallite size of the TNTs is larger and the degree of the crystallinity is higher after annealing process. Moreover, annealing treatment change the crystal structure from nanotubes to anatase phase, which is chemically and optically active. ► TNTs have larger specific surface areas, higher specific pore volumes and mean pore sizes than titania nanoparticles. ► In addition, annealing treatment red-shifts the absorption edge of TNTs and narrows their optical band gap width.Titania nanotubes are synthesized via hydrothermal treatment of TiO₂ powders in NaOH solution at 110°C for 90h, followed by annealing at 400°C. The morphology of nanotubes is characterized by field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Microscopic observations on the transformation process indicate that the nanotubes retain their shapes after the annealing process. The crystalline structure and composition are examined by X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX). The results confirm the absence of impurity peaks and the crystal structure change from nanotubes to anatase phase after annealing treatment. The average specific surface area of the particles is probed using gas adsorption–desorption measurements. The prepared tubular samples exhibit greater specific surface areas and higher pore volumes than the precursor. Moreover, it is apparent that the hydrothermal treatment modifies the optical properties of the titania samples and red-shifts the UV absorption to a band gap energy of 3.04eV after annealing treatment.

Keywords: Titania nanotubes (TNTs); Annealing; Electron microscopy; Adsorption; Optical properties

Laser diffusion nitriding of Ti–6Al–4V for improving hardness and wear resistance by H.C. Man; M. Bai; F.T. Cheng (pp. 436-441).

► Solid-state laser diffusion nitriding successfully achieved on Ti–6Al–4V. ► Surface roughness remained almost unchanged in diffusion nitriding. ► Compared with the substrate the hardness was increased by about 2.3 times. ► Wear resistance was increased by about 8 times.Owing to poor tribological properties, titanium (Ti) alloys are usually surface-treated to enhance their surface properties. Laser surface nitriding, among others, is a common method employed to increase hardness and wear resistance for Ti alloys. Conventional laser nitriding involves surface melting of Ti alloys in a nitrogen atmosphere. This inevitably results in a roughened surface and post-treatment might be required. The present study aims at laser diffusion nitriding Ti alloys without surface melting via carefully selecting the laser processing parameters. The nitrided surface was characterized by X-ray diffractometry (XRD), optical microscopy (OM), scanning-electron microscopy (SEM), and profilometry. The nitride layer formed was about 1.62μm upon repeated passes. The change in surface roughness resulting from laser diffusion nitriding was only minimal. Nanoindentation measurements revealed that the hardness of the nitride layer was around 11.3GPa, being about 2.3 times that of Ti–6Al–4V. Ball-on-slab sliding wear test recorded a reduction in wear volume by about 8 times. The results of the present work thus demonstrate the feasibility of diffusion nitriding of Ti–6Al–4V by laser treatment for enhancing its surface properties and performance.

Keywords: Laser surface treatment; Diffusion nitriding; Roughness; Hardness; Wear

A density functional study of atomic oxygen and water molecule adsorption on Ni(111) and chromium-substituted Ni(111) surfaces by Nishith Kumar Das; Tetsuo Shoji (pp. 442-447).

► The adsorption energy of two chromium atom substituted Ni–Cr surface is found to be the strongest for chemisorption among all of the cases studied here. ► Oxygen atoms prefer to bond with Cr rather than Ni atoms. ► The hybridization occurring between the metal d orbital and the oxygen p orbital; the bonding is mainly ionic, and water bonds weakly in both cases.Density functional theory (DFT) for generalized gradient approximation calculations has been used to study the adsorption of atomic oxygen and water molecules on Ni(111) and different kind of Ni–Cr(111) surfaces. The fcc hollow site is energetically the most favorable for atomic oxygen adsorption and on top site is favorable for water adsorption. The Ni–Cr surface has the highest absorption energy for oxygen at 6.86eV, followed by the hcp site, whereas the absorption energy is 5.56eV for the Ni surface. The Ni–O bond distance is 1.85Å for the Ni surface. On the other hand, the result concerning the Ni–Cr surface implies that the bond distances are 1.93–1.95Å and 1.75Å for Ni–O and Cr–O, respectively. The surface adsorption energy for water on top site for two Cr atom substituted Ni–Cr surface is 0.85eV. Oxygen atoms prefer to bond with Cr rather than Ni atoms. Atomic charge analysis demonstrates that charge transfer increases due to the addition of Cr. Moreover, a local density of states (LDOS) study examines the hybridization occurring between the metal d orbital and the oxygen p orbital; the bonding is mainly ionic, and water bonds weakly in both cases.

Keywords: Density functional theory; Ni-based alloy; Adsorption

Sol–gel based alumina powders with catalytic applications by Maria Crişan; Maria Zaharescu; Valluri Durga Kumari; Machiraju Subrahmanyam; Dorel Crişan; Nicolae Drăgan; Mălina Răileanu; Mihaela Jitianu; Adriana Rusu; Gullapelli Sadanandam; Jakkidi Krishna Reddy (pp. 448-455).

Display Omitted► Pure and Ni-doped Al₂O₃ sol–gel nanopowders were performed. ► The introduction of Ni dopant before or after hydrolysis influences the structure.► Ni introduced after hydrolysis and physically combined with TiO₂ ensures the synergistic performance.► Our results could be a good start for the design of TiO₂–NiO/Al₂O₃ combined materials.The sol–gel process provides a new approach to the preparation of oxide materials and offers many advantages for making catalysts. Since homogeneous mixing can be achieved at the molecular scale, the chemical reactivity of the oxide surface can be greatly enhanced; thus powders with high surface area and optimized pore size distribution can be obtained at low temperatures. In the present work NiO/Al₂O₃ sol–gel catalysts were obtained by simultaneous gelation of aluminium isopropoxide and nickel nitrate. A comparative study with pure sol–gel alumina was also realized. By physical–structural studies the changes induced by the introduction of the Ni precursor, before and after aluminium alkoxide hydrolysis were highlighted. The introduction of Ni at the beginning of the reaction favors γ-Al₂O₃ crystallization. When Ni is added at the end of reaction, it delays the alumina crystallization and induces the disorder of the lattice. The obtained Ni doped sol–gel derived alumina has been used as catalyst in the finished form for glycerol reforming to generate H₂ for fuel cell applications. Some evaluation results of Ni-doped alumina combined with TiO₂ in photocatalytic glycerol reforming reaction have been included.

Keywords: NiO/Al; ₂; O; ₃; nanopowders; Sol–gel process; Structural study; Catalytic activity; Glycerol reforming

(Ti,Al,Si,C)N nanocomposite coatings synthesized by plasma-enhanced magnetron sputtering by Yanfeng Wang; Zhengxian Li; Jihong Du; Yunfeng Hua; Baoyun Wang (pp. 456-460).

► The columnar crystals are restrained by C incorporation and a typical non-columnar growth mode is obtained. ► The (Ti,Ai,Si,C)N hard coatings has a super higher hardness (about 41GPa) than that of Ti–Al–Si–N hard coatings. ► The (Ti,Ai,Si,C)N coatings have a very lower friction coefficient (about 0.18) than that of Ti–Al–Si–N hard coatings (about 0.6) and show a better wear state after friction.Materials’ surface service property could be enhanced by transition metal nitride hard coatings due to their high hardness, wear and high temperature oxidation resistance, but the higher friction coefficient (0.4–0.9) of which aroused terrible abrasion. In this work, quinternary (Ti,Al,Si,C)N hard coating 3–4μm was synthesized at 300°C using plasma enhanced magnetron sputtering system. It was found that the coating's columnar crystals structure was restrained obviously with the increase of C content and a non-columnar crystals growth mode was indicated at the C content of 33.5at.%. Both the XRD and TEM showed that the (Ti,Al,Si,C)N hard coatings had unique nanocomposite structures composed of nanocrystalline and amorphous nc-(Ti,Al)(C,N)/nc-AlN/a-Si₃N₄/a-Si/a-C. However, the coatings were still super hard with the highest hardness of 41GPa in spite of the carbon incorporation. That a-C could facilitate the graphitization process during the friction process which could improve the coating's tribological performance. Therefore, that nanocomposite (Ti,Al,Si,C)N coatings with higher hardness (>36GPa) and a lower friction coefficient (<0.2) could be synthesized and enhance the tribological performance and surface properties profoundly.

Keywords: (Ti,Al,Si,C)N hard coating; Magnetron sputtering; Mechanical properties; Tribological performance

Enhancing photoresponse time of low cost Pd/ZnO nanorods prepared by thermal evaporation techniques for UV detection by H.I. Abdulgafour; Z. Hassan; F.K. Yam; K. AL-Heuseen; Y. Yusof (pp. 461-465).

► High quality undoped ZnO nanorods have been synthesized at 850°C by vapor–solid (VS) technique without a catalyst through a low cost process on silicon substrates. ► Metal–semiconductor–metal (MSM) photodetectors with palladium (Pd) as contact electrodes have been successfully constructed for ultraviolet (UV) detection. ► It was found that the maximum responsivity of the Pd/ZnO MSM photodetector was 0.106A/W which corresponds to a quantum efficiency of 43.8% at 5V applied bias voltage.High quality undoped ZnO nanorods have been synthesized at 850°C by vapor–solid (VS) technique without a catalyst through a low cost process on silicon substrates. Then, ZnO nanorods have been characterized by using scanning electron microscopy (SEM), X-ray diffractometer (XRD), and photoluminescence (PL) spectroscopy. Metal–semiconductor–metal (MSM) photodetectors with palladium (Pd) as contact electrodes have been successfully constructed for ultraviolet (UV) detection. Under dark and UV illumination, the load resistance of the Pd/ZnO junction was found to be 80.4kΩ, and 23.5kΩ referring to the maximum allowed bias voltage; the barrier height was estimated to be about 0.8eV, and 0.76eV, at 5V applied bias voltage, respectively. It was found that the maximum responsivity of the Pd/ZnO MSM photodetector was 0.106A/W at 300nm which corresponds to a quantum efficiency of 43.8% at 5V applied bias voltage. The transient photoresponse of the fabricated device is reported under different applied biases at 1V, 3V, and 5V.

Keywords: ZnO; Photodetector; Thermionic emission; Responsivity

Surface-initiated ATRP of 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate on Phynox by Bastien Barthélémy; Sébastien Devillers; Isabelle Minet; Joseph Delhalle; Zineb Mekhalif (pp. 466-473).

Display Omitted► 11-(2-Bromoisobutyrate)-undecyl-1-phosphonic acid has been synthesized. ► 11-(2-Bromoisobutyrate)-undecyl-1-phosphonic forms a monolayer on Phynox substrate. ► This monolayer plays the role of the initiator for MPC ATRP polymerization. ► Two conditions have been used: unheated during 24h and heated at 90°C during 1h. ► Heating the system led to a more hydrophilic polymer.Phynox is of high interest for technological applications due to its high corrosion resistance, mechanical properties and biocompatibility. In combination with these remarkable characteristics, some Phynox applications require specific surface properties that can be imparted with suitable surface functionalizations of the oxide layer. The present work aims at studying the surface-initiated atom transfer radical polymerization (ATRP) of 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate (MPC) on Phynox substrates, using grafted 11-(2-bromoisobutyrate)-undecyl-1-phosphonic acid as initiator. The ability of the initiator to bind Phynox substrates and act as an initiator for ATRP of MPC is investigated. It appears that ATRP polymerization of MPC on modified Phynox substrates already takes place in aqueous media at room temperature, but the yield at 90°C is superior.

Keywords: Surface modification; Phynox; ATRP; 11-(2-Bromoisobutyrate)-undecyl-1-phosphonic acid; 2-(Methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate

Long range interactions between micro spheres and alloy surfaces in water changed by ion implantation by Li Jiang; Chen Haosheng; Liu Fengbin (pp. 474-477).

Ion implantation was adopted to change the surface potentials of samples made of aluminum bronze. The interactions between the SiO₂ particles and the sample surfaces in water were changed from attractive to repulsive. According to the surface element integration method, this interaction was simulated and the electrostatic double layer force was considered to be the dominated factor. This long range repulsive interaction was proved to have effect on preventing micro particles approaching the alloy surface by the fluorescent particles adhesion experiment, and the technology of ion implantation may have potential applications in adhesion resistance and abrasion reduction for alloys running in water.

Keywords: Surface force; Electrostatic double layer; Surface potential; Ion implantation; AFM

Fabrication and adhesion performance of gold conductive patterns on silicon substrate by laser sintering by Zhixiang Cai; K.C. Yung; Xiaoyan Zeng (pp. 478-481).

The microstructure of gold conductive patterns became denser with increase of laser power. The gold film treated with laser power of 2W showed poor adhesiveness of 2B in accordance with ASTM D3359-08. The adhesion level of gold film increased to 5B by elevating laser power to 8W. Al wire was successfully bonded to sintered gold conductive patterns and has sufficient tensile strength. It has been successfully used in the fabrication of microwave device.Display Omitted► We investigate the effects of laser power on microstructure and adhesion of gold conductive patterns. ► The microstructure of gold film became denser with increase of laser power. ► Elevating laser power will increase the adhesion of gold film. ► The adhesion mechanism corresponds to physical adsorption and chemical bond mechanisms. ► Al wire was successfully bonded to sintered gold conductive patterns.Laser sintering of gold-microparticle ink was examined in this study. Laser-sintered gold conductive patterns were characterized by using scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), cross-cut tape test and destructive bond wire pull tests. The effects of laser power on microstructure and adhesion of gold conductive patterns were investigated. It was found that the microstructure of gold conductive patterns became denser with increase of laser power. The gold conductive patterns treated with laser power of 2W showed poor adhesiveness of 2B in accordance with ASTM D3359-08. The adhesion level of gold conductive patterns increased to 5B by elevating laser power to 8W. The adhesion mechanism of gold conductive patterns on silicon substrate was discussed and wire bonding test was also performed on gold conductive patterns. Wire breakage took place at the practical pull strength of around 5gf.

Keywords: Laser sintering; Gold conductive patterns; Microstructure; Adhesion

Characterization of poly (3-methyl thiophene) thin films prepared by modified chemical bath deposition by Sandip V. Kamat; J.B. Yadav; Vijaya Puri; R.K. Puri; O.S. Joo (pp. 482-488).

.Display Omitted► The conventional CBD method was modified for the deposition of P3MeT thin films. ► The variation in oxidant concentration influences the properties of P3MeT thin films. ► Surface morphology becomes smoother with low roughness and reduction in defects. ► The contact angle and band gap decreases where as optical absorbance and refractive index increases with increase in oxidant concentration.Poly (3-methyl thiophene) thin films were prepared by chemical bath deposition technique on glass substrate; the prepared thin films were characterized for structural, morphological and optical properties. The variation in the oxidant concentration has an influence on the properties of the P3MeT thin films. The increase in the oxidant concentration leads to increase in the thickness of the film. The binding energy increases due to increase in oxidation concentration. The P3MeT thin films show smooth surface morphology with increase in oxidant concentration whereas the contact angle of the thin film decreases with increase in oxidant concentration. The optical absorbance of these thin films was found to increase with decrease in the optical band gap due to increase in oxidant concentration.

Keywords: Polymer; Thin films; Chemical synthesis; XPS; Optical properties

Surface modification of titanium membrane by chemical vapor deposition and its electrochemical self-cleaning by X.W. Li; J.X. Li; C.Y. Gao; M. Chang (pp. 489-493).

► A new composite membrane Ti/BDD, made by depositing CVD (chemical vapor deposition) boron-doped diamond (BDD) film on titanium(Ti) membrane to modify porous titanium membrane surface, is brought forward. ► Preparation of Ti/BDD composite membrane and its application in membrane cleaning is discussed in this paper. ► Results shows that based on the unique electrochemical properties of BDD, cleaning level of this composite Ti/BDD membrane is significantly increased, making membrane life and efficiency improved prominently.Membrane separation is applied widely in many fields, while concentration polarization and membrane fouling, limiting its promotion and application greatly, are the bottlenecks in membrane application. Among which, membrane fouling is irreversible, membrane must be periodically cleaned or even replaced to restore permeability. Membrane cleaning has become one of the key issues in membrane separation areas. Considering incomparable electrochemical advantages of boron-doped diamond (BDD) film electrode over conventional electrode, a new composite membrane Ti/BDD, made by depositing CVD (chemical vapor deposition) boron-doped diamond film on titanium(Ti) membrane to modify porous titanium surface, that can be cleaned electrochemically is proposed. Feasibility of its preparation and application is discussed in this paper. Results shows that based on the unique electrochemical properties of diamond, cleaning level of this composite Ti/BDD membrane is significantly increased, making membrane life and efficiency improved prominently.

Keywords: Boron-doped diamond (BDD); Electrochemistry; Membrane cleaning

Effect of substrate texture on the growth of hematite nanowires by Himanshu Srivastava; Pragya Tiwari; A.K. Srivastava; Sanjay Rai; Tapas Ganguli; S.K. Deb (pp. 494-500).

► Demonstration for the first time that in annealing method foil textures greatly affects the nanowire growth. ► Synthesis of dense and aligned hematite nanowires by simple annealing technique in moist oxygen ambient. ► Demonstration that by simple filing and cutting iron foil, the surface texture can be changed and the growth of hematite nanowires can be enhanced. ► Study of effect of substrate texture on the growth of hematite nanowires. ► Growth mechanism to explain the effect of texture and moisture on the growth of nanowires.The effect of texture of iron foil substrate on the growth of hematite nanowires by annealing method has been investigated in detail. Three substrates of different textures were prepared from a [200] oriented iron foil by some simple processes. The hematite nanowires on these substrates were synthesized by annealing iron foil at 700°C in moist oxygen. The growth pattern of nanowires on these substrates showed that the growth of hematite nanowires depends strongly on the iron substrate texture and [110] oriented iron grains are necessary for their growth. The samples were characterized by Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), X-ray diffraction (XRD), Electron Back Scatter Diffraction (EBSD) and Raman Spectroscopy. We have also tried to explain the various observations on the mechanism of growth. Mainly, the presence of water vapor significantly enhanced the formation of hematite nanowires which resulted in a very dense and aligned growth of nanowires on the substrate areas of favorable texture. Finally, the study proved the substrate texture to be a powerful tool to control growth of nanowires and can be used efficiently for patterning and large scale synthesis of the nanowires.

Keywords: A1. Nanostructures; A1. X-ray diffraction; B1. Nanomaterials; B2. Semiconducting material

Drastic change in shape of tetragonal TeO₂ nanowires and their application to transparent chemical gas sensors by Sang Sub Kim; Jae Young Park; Sun-Woo Choi; Han Gil Na; Ju Chan Yang; Dong Sub Kwak; Hyun Jung Nam; Chang Kwon Hwangbo; Hyoun Woo Kim (pp. 501-506).

► Synthesis of TeO₂ nanowires by heating Te powders. ► Drastic morphological changes by varying the temperature. ► High transmission in the visible regime and reliable NO₂ sensing properties.We have synthesized one-dimensional structures of tellurium dioxide (TeO₂) by heating of tellurium powders. Their morphology was drastically changed as the growth temperature increased in the range of 400–500°C, in which high-temperature process facilitated the thickening of the stem nanowires, as well as the growth of secondary branches on the stems. The obtained TeO₂ products were crystalline with tetragonal structure. The TeO₂ nanowire film exhibited a high transmission rate of about 73%. We have investigated the NO₂ sensing properties of the as-fabricated TeO₂ nanowires, in which a linear relationship between sensitivity and the NO₂ gas concentration was observed. Thus, the TeO₂ nanowires demonstrated their potential application to transparent chemical sensors.

Keywords: Nanostructures; Chemical synthesis; Transmission electron microscopy

Synthesis and characterization of rodlike liquid crystalline polyester/multi-walled carbon nanotubes and study of their thermal stability by Wu-Quan Hu; Zhen-Kai Cui; Jun Jin; Zheng-Ping Dong; Shu-Wen Li; Peng Wang; Wen Ding; Rong Li (pp. 507-512).

Display Omitted► TLCP and nanocomposites containing MWNT was synthesized by in situ polymerization. ► The mesophase range of nanocomposite were widened and shifted to higher temperatures. ► The melting phase transition ( T_m) value was increased maximally by 38.4°C. ► The PE/M-0.5 gave the best performance in terms of the thermal stability.Rodlike thermotropic liquid crystalline polyester (TLCP) was synthesized from 4,4′-oxydibenzoyl chloride and resorcinol containing modified multi-walled carbon nanotubes (MWCNTs) by in situ high-temperature solution polymerization. The liquid crystalline properties and thermal stability of the resulted TLCP nanocomposites were characterized by XRD, DSC, TGA, SEM, POM, and optical analysis. The addition of small amount of MWCNTs into TLCP matrix could significantly improve the thermal stability. The mesophase temperature range of nanocomposites were widened and shifted to higher temperatures. This nanocomposite melting phase transition ( T_m) value increases maximally to 38.4°C compared with pure copolymer. Using the Horowits–Metzger kinetic method, the PE/M-0.5 gave the best performance in terms of the thermal stability. This result can be explained that the incorporation of MWCNTs into TLCP caused an interaction between TLCP and MWCNTs through π–π* conjugation.

Keywords: Liquid crystal polymer; Carbon nanotubes; Nematic; Thermal properties; π–π* Conjugation

Effects of air dielectric barrier discharge plasma treatment time on surface properties of PBO fiber by Qian Wang; Ping Chen; Caixia Jia; Mingxin Chen; Bin Li (pp. 513-520).

► Air DBD plasma treatment time had great influence on PBO fiber surface properties. ► Surface wettability of PBO fiber can be improved effectively by plasma treatment. ► PPESK resin showed better wetting behavior on the plasma treated fiber. ► There exists an optimum treatment condition for PBO fiber treated by air DBD plasma.In this paper, the effects of air dielectric barrier discharge (DBD) plasma treatment time on surface properties of poly( p-phenylene benzobisoxazole) (PBO) fiber were investigated. The surface characteristics of PBO fiber before and after the plasma treatments were analyzed by dynamic contact angle (DCA) analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). DCA measurements indicated that the surface wettability of PBO fiber was improved significantly by increasing the fiber surface free energy via air DBD plasma treatments. The results were confirmed by the improvement of adhesion of a kind of thermoplastic resin to PBO fiber which was observed by SEM, showing that more resin was adhering evenly to the fiber surface. AFM measurement revealed that the surface topography of PBO fiber became more complicated and the surface roughness was greatly enhanced after the plasma treatments, and XPS analysis showed that some new polar groups (e.g.OCO) were introduced on plasma treated PBO fiber surface. The results of this study also showed that the surface properties of PBO fiber changed with the elongation of plasma treatment time.

Keywords: PBO fiber; Air DBD plasma; Surface modification; Surface analysis

Laser sintering of Cu paste film printed on polyimide substrate by Myungo Joo; Byoungyoon Lee; Sooncheol Jeong; Myeongkyu Lee (pp. 521-524).

► Highly conductive Cu films are printed on polyimide substrate by sintering Cu paste with laser. ► Sintered films are mechanically robust and very compact microstructure is observed throughout the whole thickness. ► Laser-sintered film shows an electrical resistivity comparable to that of thermally sintered film.We here show that highly conductive copper films are obtainable from Cu paste by laser sintering. The Cu paste synthesized using an organo-metallic compound was screen-printed onto polyimide substrate and the printed films were scanned by an ultraviolet laser beam at 355nm under nitrogen atmosphere. Very compact microstructure was observed throughout the whole thickness and the sintered films were mechanically robust. Although Cu is known susceptible to oxidation, no Cu oxides were incorporated into the film during laser sintering. An electrical resistivity of 1.86×10⁻⁵Ωcm was obtained. This resistivity is several orders of magnitude lower than those reported for the copper nanoparticle paste thermally sintered under N₂ or H₂ atmosphere.

Keywords: Cu paste; Laser sintering; Flexible substrate

The important role of Mn³⁺ in the room-temperature ferromagnetism of Mn-doped GaN films by B. Hu; B.Y. Man; C. Yang; M. Liu; C.S. Chen; X.G. Gao; S.C. Xu; C.C. Wang; Z.C. Sun (pp. 525-529).

► Mn³⁺ substituted the Ga sites is believed to be the decisive factor in the origin of room-temperature ferromagnetism. ► The better room-temperature ferromagnetism is given with the higher Mn³⁺ concentration. ► The bound magnetic polarons (BMP) theory can be used to prove our room-temperature ferromagnetic properties. ► Higher annealing temperature (such as 1150°C) is not expected because of the second phase Mn_xGa_y formation.Mn-doped GaN films (Ga1−_xMn_xN) were grown on sapphire (0001) using Laser assisted Molecular Beam Epitaxy (LMBE). High-quality nanocrystalline Ga1−_xMn_xN films with different Mn concentration were then obtained by thermal annealing treatment for 30min in the ammonia atmosphere. Mn ions were incorporated into the wurtzite structure of the host lattice by substituting the Ga sites with Mn³⁺ due to the thermal treatment. Mn³⁺, which is confirmed by XPS analysis, is believed to be the decisive factor in the origin of room-temperature ferromagnetism. The better room-temperature ferromagnetism is given with the higher Mn³⁺ concentration. The bound magnetic polarons (BMP) theory can be used to prove our room-temperature ferromagnetic properties. The film with the maximum concentration of Mn³⁺ presents strongest ferromagnetic signal at annealing temperature 950°C. Higher annealing temperature (such as 1150°C) is not proper because of the second phase Mn_xGa_y formation.

Keywords: PACS; 61.10.Nz; 61.72.Vv; 75.50.Pp; 81.05.Ea; 81.15.FgLaser assisted molecular beam epitaxy; Room-temperature ferromagnetism; Annealing temperature; Gallium manganese nitride; Mn valence; BMP

Effects of rapid thermal annealing on the structural properties of TiO₂ nanotubes by J.Y. Lin; Y.T. Chou; J.L. Shen; M.D. Yang; C.H. Wu; G.C. Chi; W.C. Chou; C.H. Ko (pp. 530-534).

► TiO₂ nanotubes with rapid thermal annealing (RTA) and thermal annealing were studied. ► Raman peak in TiO₂ nanotubes redshifts and reduces its linewidth after annealing. ► RTA is an effective tool for amorphous–anatase transformation in TiO₂ nanotubes.The structural properties of TiO₂ nanotubes with rapid thermal annealing (RTA) and traditional thermal annealing in O₂ were studied by X-ray diffraction (XRD) and Raman scattering measurements. From analyzing the line width of XRD and the correlation length of the Raman peak, we demonstrate that RTA can be an effective tool for amorphous–anatase transformation in TiO₂ nanotubes. The Raman peak redshifts and reduces its line width after thermal annealing and RTA, which may involves the reduction of oxygen-related defects.

Keywords: PACS; 61.46.Fg; 61.05.C−; 78.30.−jTiO; ₂; Nanotubes; Raman scattering; Rapid thermal annealing

Elevated temperature dry sliding wear behavior of nickel-based composite coating on austenitic stainless steel deposited by a novel central hollow laser cladding by Xiang-Ming He; Xiu-Bo Liu; Ming-Di Wang; Mao-Sheng Yang; Shi-Hong Shi; Ge-Yan Fu; Shu-Fa Chen (pp. 535-541).

► A Ni-based composite coating was fabricated by a novel central hollow laser cladding. ► The fusion line is very flat and straight due to the relatively uniform energy distribution of the central hollow beam. ► The coating exhibits superior wear resistance than substrate either at ambient or high temperatures. ► The coating shows better wear resistance at 600°C than 300°C owing to polishing effect and lubricious oxides films.In order to improve the high-temperature wear resistance of austenitic stainless steel, a wear resistant composite coating reinforced with hard (Cr,Fe)₇C₃ carbide and toughened by ductile γ-(Ni,Fe)/(Cr,Fe)₇C₃ eutectic matrix was fabricated by a novel central hollow laser cladding technique. The constituent phases and microstructure as well as high-temperature tribological behaviors of the Ni-based coating were investigated, respectively, and the corresponding wear mechanisms were discussed. It has been found that the composite coating exhibits superior wear resistance than substrate either at ambient or high temperatures. The coating shows better sliding wear resistance at 600°C than 300°C owing to high-temperature stability of the reinforced carbide and polishing effect as well as formation of continuous lubricious films, which implied it has large potential industrial applications at relatively higher temperatures.

Keywords: Austenitic stainless steel; Central hollow laser cladding; Ni-based composite coating; High-temperature wear resistance

The influence of growth temperatures on the characteristics of GaN nanowires by L.L. Low; F.K. Yam; K.P. Beh; Z. Hassan (pp. 542-546).

► Synthesis of GaN nanowires at various growth temperatures, i.e. 750°C, 850°C, 900°C, 950°C, and 1000°C. ► Study the effect of growth temperatures on the morphological, structural and optical characteristics of GaN nanowires. ► Study the presence of phonon replicas in the blue emission of photoluminescence spectra of synthesized GaN nanowires.This paper presents the investigation of the properties of GaN nanowires synthesized from Ni-catalyzed chemical vapour deposition method under various growth temperatures. The influence of the growth temperatures on the morphological, structural and optical characteristics of the synthesized GaN nanowires was investigated in this work. Field-emission scanning electron microscopy images revealed that the 950°C was the optimal growth temperature for synthesizing uniform, straight and smooth morphology of GaN nanowires. X-ray diffraction results demonstrated that the synthesized low dimensional GaN structures have the hexagonal wurtzite structure. Ultraviolet and blue emissions were detected from photoluminescence measurements. In addition, phonon replicas with the energy separation of 90meV have been observed at the lower energy of the blue emission region in photoluminescence spectra.

Keywords: GaN; Nanowires; Chemical vapour deposition; Vapour–liquid–solid; Growth temperature

Enhanced antibacterial performance of hybrid semiconductor nanomaterials: ZnO/SnO₂ nanocomposite thin films by Nasrin Talebian; Mohammad Reza Nilforoushan; Elahe Badri Zargar (pp. 547-555).

► Preparation of ZnO/SnO₂ hybrid nanostructure films with a sustainable photocatalytic antibacterial activity compared with single component semiconductors. ► Chemical composition critically influences the improved antibacterial performance of hybrids. ► Bacterial growth inhibition observed under dark conditions, indicating undetermined mechanisms additional to photocatalytic ROS production for toxicity.The nano-sized coupled oxides ZnO/SnO₂ thin films in a molar ratio of 2:1 (Z2S), 1:1 (ZS) and 1:2 (ZS2) were prepared using sol–gel dip coating method and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–vis spectroscopy. Escherichia coli ( E. coli, ATCC 25922) was selected as a model for the Gram-negative bacteria to evaluate antibacterial property of composite samples compared with single ZnO (Z) and single SnO₂ (S) films. The antibacterial activity has been studied applying the so-called antibacterial drop test under UV illumination. The bactericidal activity was estimated by relative number of bacteria survived calculated from the number of viable cells which form colonies on the nutrient agar plates. The influence of the SnO₂–ZnO nanocomposite composition on the structural features and on the antibacterial properties of the thin films are reported and discussed. It is found that all coatings exhibited a high antibacterial activity. The coupled oxide photocatalyst Z2S has better photocatalytic activity to bacteria inactivation than ZS, ZS2, Z and S films. Furthermore, nanostructured films were active even in the absence of irradiation.

Keywords: Zinc oxide/tin dioxide nanocomposite; Antibacterial activity; Sol–gel film

Seed-assisted growth of epitaxial ZnO nanorod arrays with self-organized periodicity and directional alignment by Hou-Guang Chen; Zheng-Wei Li (pp. 556-564).

► We report a seed-assisted growth of epitaxial ZnO nanorod (NR) arrays on sapphire substrates. ► The self-organized periodic ZnO NRs can be grown on substrates without the pre-patterning processes. ► The spatial ordering of the ZnO NRs was influenced by the seed growth conditions and substrate surface. ► Post-growth annealing of the ZnO seeds changed the morphologies and alignment of the ZnO NRs.In this article we report the seed-assisted growth of epitaxial ZnO nanorod (NR) arrays on (0001) plane sapphire substrates at low temperatures in aqueous solutions. The self-organized periodic ZnO NR rows with a fairly constant separation were directly grown on bare sapphire surfaces, without the need for any complicated lithography or use of pre-patterned catalysts. The spatial ordering of the ZnO NRs was significantly influenced by the seed growth conditions and by the presence of a self-organized step structure on the annealed sapphire surface. In addition, the effect of the conditions employed to prepare the seeds, including growth parameters and post-growth annealing treatment, on the epitaxial relationship between the ZnO NRs and the sapphire substrate was systematically investigated by X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM) observations. Post-growth annealing of the ZnO seeds changed the morphologies and crystallographic alignment of the generated ZnO nanostructures significantly, as a result of the formation of epitaxial spinel ZnAl₂O₄ interlayers, facilitated by zinc cation diffusion and solid state reactions at high temperature.

Keywords: ZnO; MOCVD; Hydrothermal; Epitaxial growth; Nanostructure; XRD; TEM

Preparation and ablation properties of ZrC–SiC coating for carbon/carbon composites by solid phase infiltration by Zhaoqian Li; Hejun Li; Wei Li; Jie Wang; Shouyang Zhang; Juan Guo (pp. 565-571).

► We prepare a novel ZrC–SiC coating on carbon/carbon (C/C) composites surface by solid phase infiltration. ► We study the ablation properties of the coatings under oxyacetylene flame and analysis their ablation mechanism. ► Developing economical and high-efficiency approach to improve the ablation properties of C/C composites. ► Increasing information will useful to C/C composites for ultra high temperature and aerospace applications.A novel ZrC–SiC coating was prepared on carbon/carbon (C/C) composites surface by solid phase infiltration and the ablation properties of the ZrC–SiC coated C/C composites under oxyacetylene flame were studied. The results show that the coating prepared on the condition of optimum process parameters exhibits dense surface and outstanding anti-ablation ability. After ablation for 20s, the mass ablation rates of the coated C/C composites can be lowered to 2.36×10⁻³g/s, 37.1% reduction compared with uncoated C/C composites. The oxide layer composed of ZrO₂ and SiO₂ acts as oxygen diffusion barrier and the evaporation of ZrO₂ and SiO₂ absorbs a great amount of heat from the flame and reduces the erosive attack on the coating.

Keywords: Carbon/carbon composites; Solid phase infiltration; ZrC–SiC coating; Ablation properties

Interface and its effect on the interlaminate shear strength of novel glass fiber/hyperbranched polysiloxane modified maleimide-triazine resin composites by Ping Liu; Qingbao Guan; Aijuan Gu; Guozheng Liang; Li Yuan; Jianfei Chang (pp. 572-579).

► Hydroxyl groups on surfaces of glass fibers react with Si–OH groups of hyperbranched polysiloxane, forming chemical and hydrogen bonds. ► The chemical and hydrogen bonds provide improved interfacial adhesion between hyperbranched polysiloxane modified maleimide-triazine (mBT) resin and glass fibers. ► Original maleimide-triazine resin does not have good interfacial adhesion with glass fibers. ► Better interfacial adhesion guarantees a desirable property-transition from the matrix to the resultant composites. ► Novel advanced glass woven fabric/mBT resin composites with higher interlaminate shear strengths are developed.Interface is the key topic of developing advanced fiber reinforced polymeric composites. Novel advanced glass woven fabric (GF) reinforced composites, coded as GF/mBT, were prepared, of which the matrix resin was hyperbranched polysiloxane (HBPSi) modified maleimide-triazine (mBT) resin. The influence of the composition of the matrix on the interfacial nature of the GF/mBT composites were studied and compared with that of the composite based on GF and BT resin using contact angle, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and dielectric properties over wide frequency and temperature ranges. Results show that the interfacial nature of the composites is dependent on the chemistries of the matrices, mBT matrices have better interfacial adhesion with GF than BT resin owing to the formation of chemical and hydrogen bonds between mBT resin and GF; while in the case of mBT resins, the content of HBPSi also plays an important role on the interfacial feature and thus the macro-performance. Specifically, with increasing the content of HBPSi in the matrix, the interlaminate shear strength of corresponding composites significantly improves, demonstrating that better interfacial adhesion guarantees outstanding integrated properties of the resultant composites.

Keywords: Interface; Composites; Hyperbranched polysiloxane; Glass fiber; Interlaminate shear strength

Novel strategy in increasing stability and corrosion resistance for super-hydrophobic coating on aluminum alloy surfaces by Bo Yin; Liang Fang; An-qiong Tang; Qiu-liu Huang; Jia Hu; Jian-hui Mao; Ge Bai; Huan Bai (pp. 580-585).

► A super-hydrophobic coating is prepared on the anodized aluminum alloy. ► The surface is composed of leaf-like structures. ► Good chemical stability in air. ► Enhanced corrosion performance.A novel super-hydrophobic coating was prepared by chemical modification on the anodized aluminum alloy surface. The surface structure was characterized by water contact angle measurement, scanning electron microscopy (SEM), and the composition was measured by X-ray photoelectron spectroscopy (XPS). The corrosion behavior of the super-hydrophobic coating was evaluated by the polarization curve and the electrochemical impedance spectroscopy (EIS). It was found that the static water contact angle on the surface of super-hydrophobic coating was as high as 167.7±1.2°, and the sliding angle was 5°. The super-hydrophobic coating resulted in excellent corrosion resistance property and the super-hydrophobic coating showed a good stability.

Keywords: Aluminum alloy; Corrosion resistance; Super-hydrophobic coating; Electrochemical

Ultrasound-assisted anodization of aluminum in oxalic acid by Rong Zhang; Kaiming Jiang; Yun Zhu; Haiyang Qi; Guqiao Ding (pp. 586-589).

► Ultrasound is successfully introduced into the anodization of aluminum in oxalic acid. ► Ultrasound can bring highly ordered porous anodic alumina. ► Ultrasound can significantly improve the growth rate of the oxide layer.Porous anodic alumina is an important nanoscale template for fabrication of various nanostructures. We report a new ultrasound-assisted anodization process in oxalic acid. Under the continuous irradiation of ultrasound, the one-step-anodized sample has a smooth and clean surface, and two-step-anodization brings ordered porous anodic alumina with higher growth rate of 52μm/h. The ultrasound applied during the anodization can clean the surface and enhance the nanopore growth since it can accelerate the oxide dissolving on the electrolyte/oxide interface. The ultrasound-assisted anodization may be utilized for other anodizations.

Keywords: Porous materials; Ultrasound; Anodization; Anodic alumina; Corrosion

Synthesis, characterization and comparison of sediment electro-codeposited nickel–micro and nano SiC composites by P. Narasimman; Malathy Pushpavanam; V.M. Periasamy (pp. 590-598).

► Ni–nano β-SiC composite was produced by sediment electro-co-deposition technique. ► Production of nanocomposite was more difficult than microcomposite. ► SiC incorporation by SECD method was much higher than that by CECD method. ► Roughness of the nanocomposite is much lower. ► The hardness of nanocomposite was higher for a given vol.% of SiC in deposit. ► Scratch and wear resistance of the nanocomposite were higher than that of microcomposite.Nickel–silicon carbide composites were produced using 1μm and 50nm size powders from a conventional Watt's bath using tetra methyl ammonium hydroxide as the surfactant. Sediment codeposition technique with horizontal electrodes was used. The effect of silicon carbide concentration and bath operating parameters on the volume percents and deposition rates of coatings obtained with the two different particles was studied. Substantial improvements in mechanical properties such as hardness, wear resistance, scratch resistance and roughness were obtained with the nanocomposite material, as compared with composites containing microsized particles.

Keywords: β-SiC micro/nanocomposites; Sediment electro-codeposition; Hardness and wear testing; Scratch testing; Roughness; Surface morphology

Cr-doping induced ferromagnetic behavior in antiferromagnetic EuTiO₃ nanoparticles by T. Wei; Q.G. Song; Q.J. Zhou; Z.P. Li; X.L. Qi; W.P. Liu; Y.R. Guo; J.-M. Liu (pp. 599-603).

► High quality EuTi1−_xCr_xO₃ ( x=0.0, 0.02, and 0.04) nanoparticles with size about 100nm were synthesized by simple sol–gel technique. ► Structural and magnetic properties of these nanoparticles were investigated. ► G-type antiferromagnetic (G-AFM) order of EuTiO₃ can be significantly modified with slight Cr-doping. ► Ferromagnetism (FM) is greatly enhanced for EuTi1−_xCr_xO₃ ( x=0.02 and 0.04).We have synthesized a series of high quality EuTi1−_xCr_xO₃ ( x=0.0, 0.02, and 0.04) nanoparticles by simple sol–gel technique. The averaged grain size of these obtained nanoparticles displays no obvious change with Cr-doping and is about 100nm. The structural and magnetic properties of EuTi1−_xCr_xO₃ ( x=0.0, 0.02, and 0.04) samples were detailedly investigated. It is found that the G-antiferromagnetic (G-AFM) ordering of pure EuTiO₃ can be significantly modified with slight Cr-doping, and finally the ferromagnetic behavior is enhanced for EuTi1−_xCr_xO₃ system with Cr-doping.

Keywords: PACS; 81.07.−b; 78.67.−nEuTiO; ₃; Nanoparticles; Magnetic properties

Effects of post-deposition rapid thermal annealing on aluminum-doped ZnO thin films grown by atomic layer deposition by Yung-Chen Cheng (pp. 604-607).

► ALD-grown AZO thin films were treated by post-deposition RTA at 950°C for 5min. ► RTA facilitates diffusions of Al atoms (acting as donor) in polycrystalline AZO structures. ► RTA induces the increase of local biaxial compressive strain.Aluminum-doped ZnO (AZO) thin films with alternating stacks of ZnO and Al₂O₃ were grown by atomic layer deposition (ALD) on c-face sapphire substrates. Post-deposition rapid thermal annealing (RTA) at 950°C for 5min was conducted in all AZO samples. The X-ray diffraction patterns demonstrate that the intensity of cubic ZnAl₂O₄ (311) peaks grow with the increase of Al content, which implies the diffusion of Al atoms into ZnO. The reduction of dominant peak intensity of cubic ZnO (111) and the increase of hexagonal ZnO (100) and (101) peaks intensity suggest that there were variations of crystal structures for the samples with Al content above 6%. Two orders of magnitude of electron concentration raises in samples with 2 and 4% Al content compared with the as-grown without RTA-treated samples. It also infers that RTA facilitates diffusion of Al atoms in AZO material structures and activation of Al dopants. When Al content is above 6%, the variations of crystal structures with the enhancement of biaxial compressive strain result in blue shift in energy of photoluminescence peak and in frequency ofE2high phonon mode of micro-Raman spectra. The deterioration of crystal quality due to the increase of strain-induced defects hinders the electrical and optical performance when Al doping concentration is above 6% in AZO materials.

Keywords: Atomic layer deposition; Rapid thermal annealing; Aluminum-doped ZnO

EBSD and AFM observations of the microstructural changes induced by low temperature plasma carburising on AISI 316 by Santiago Corujeira Gallo; Hanshan Dong (pp. 608-613).

► The microstructure of AISI 316 samples was observed before and after plasma carburising treatments. ► The changes in the microstructure were analysed by OM, AFM, and SEM with EBSD. ► The residual stresses developed during plasma carburising introduced microstructural changes in the treated layer. ► The effects of these changes on mechanical properties, tribological performance and corrosion resistance are discussed.Low temperature plasma carburising (LTPC) has been increasingly accepted as a hardening process for austenitic stainless steels because it produces a good combination of tribological and corrosion properties. The hardening mechanism is based on the supersaturation of the austenitic structure with carbon, which greatly hardens the material, significantly expands the fcc unit cell, produces high levels of compressive residual stresses and, ultimately, leads to the occurrence of deformation bands and rotation of the crystal lattice.The microstructural changes introduced during plasma carburising have a significant impact on the mechanical, tribological and corrosion performance and, for this reason, the microstructure of expanded austenite or S-phase has been extensively studied. However, modern surface characterisation techniques could provide new insights into the formation mechanism of S-phase layers.In this work, backscattered electron diffraction and atomic force microscopy were used to characterise the surface layers of expanded austenite produced by LTPC in an active screen furnace. Based on the experimental results, the plastic deformation, its dependence on crystallographic orientation, the evolution of grain boundaries, and their effects on mechanical, tribological and corrosion properties are discussed.

Keywords: Abbreviations; LTPC; low temperature plasma carburising; COM; crystal orientation mapPlasma carburising; Active screen; Expanded austenite; Microstructure

Mechanical responses of Zn1−_xMn_xO epitaxial thin films by Teng-Ruey Chang; Chien-Huang Tsai (pp. 614-617).

► We evaluate the nanomechanical damage of the Zn1−_xMn_xO system. ► The mechanical properties of the Zn1−_xMn_xO system film is influenced by the dominant crystal texture due to higher Mn contents. ► The measured values of H and E of the Zn1−_xMn_xO films were increased due to the high concentration of Mn rather than that of Zn only.In this study, we used nanoindentation to investigate the effect of the doping of Mn into ZnO buffer layers on the epitaxial growth of ZnO through plasma-assisted molecular beam epitaxy on c-plane sapphire substrates. We characterized the variation of the mechanical properties of Zn1−_xMn_xO alloys as a function of the Mn content in the range ( x) from 0 to 0.16, as well as analyzing their microstructures using high-resolution transmission electron microscopy. The presence of the Mn-doped ZnO buffer layer enhanced the nanomechanical properties of the ZnO epilayers significantly. From their Berkovich indenter responses, plots of the Young's modulus ( E) and hardness ( H) of these films revealed that the value of E increased relatively steadily upon increasing the Mn composition, whereas the value of H reached its maximum when x was equal to 0.16. This discrepancy suggests that Zn1−_xMn_xO epilayers of higher Mn contents had higher shear resistances.

Keywords: Plasma-assisted molecular beam epitaxy; Nanoindentation; High-resolution transmission electron microscopy; Hardness

Surface-initiated reverse atom transfer radical polymerization (SI-RATRP) for blood-compatible polyurethane substrates by Chunyan Lu; Ninglin Zhou; Dong Xu; Yida Tang; Suxing Jin; Yue Wu; Jian Shen (pp. 618-626).

PU substrates functionalized by MPC with different reaction time had a better blood compatibility compared to pristine PU (PU-Si-g-P(MPC)-12h, PU-Si-g-P(MPC)-24h and PU-Si-g-P(MPC)-36h showed a 38.1%, 52.8% and 42.9% decreasement in the amount of protein absorbed compared to pristine PU, respectively).Display Omitted► A facile and efficient approach for surface modification of PU was introduced. ► MPC was grafted onto the surface of PU film by SI-RATRP. ► CPTM was first adopted to serve as a coupling agent as well as a ligand in SI-RATRP. ► The obtained PUs had good blood compatibility and a possible usage in biomedicine.A well-defined polymer brushes (2-(methacryloyloxy) ethyl phosphorylcholine, MPC) grafted from the polyurethane (PU) substrate by surface-initiated reverse atom transfer radical polymerization (SI-RATRP) was studied. In this work, a kind of silane coupling agent (3-chloropropyltrimethoxysilane, CPTM) was adopted to serve as a coupling agent as well as a ligand for the first time. Surface structure, wettability, morphology of the PU substrates before and after modification were characterized by Fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopy measurement (XPS), Atomic force microscope (AFM), Water contact angle measurement, respectively. The results showed that zwitterionic brushes were successfully fabricated on the PU surfaces, and the content of the grafted layer increased gradually with the polymerization time. The blood compatibility of the PU substrates was evaluated by protein adsorption tests and platelet adhesion tests in vitro. It was found that all the PU functionalized with zwitterionic brush showed improved resistance to nonspecific protein adsorption and platelet adhesion.

Keywords: 2-(Methacryloyloxy) ethyl phosphorylcholine (MPC); Polyurethane (PU); Silane coupling agent; Zwitterionic brush; Blood compatibility

Identification of the reconstruction and bonding structure of SiC nanocrystal surface by infrared spectroscopy by J.Y. Fan; H.X. Li; N. Zhang; R.F. Lu (pp. 627-630).

► We studied surface chemistry and structure of SiC nanocrystals by infrared spectroscopy. ► We found Si–Si surface reconstruction and oxygen bridging bonding structure. ► The surface chemistry varies for different-sized particles. ► The surface structures accounts for the luminescence properties.We studied the surface structures of the cubic SiC nanocrystals by use of infrared spectroscopy. It was found that the Si–Si surface reconstruction occurs significantly in these nanocrystals. Besides, the oxygen bridge bond dominates their surface structure, which ensures the occurrence of ultra stable quantum-confinement photoluminescence. The larger crystallites exhibit much weaker infrared signals, but show longitudinal phonon mode that is absent in the small particles. The nanocrystals dispersed in lower-polarity solvent exhibit additional surface bonding structure other than that in water solvent.

Keywords: SiC quantum dot; Surface structure; Surface reconstruction

Characterization of passive film on 2205 duplex stainless steel in sodium thiosulphate solution by H. Luo; C.F. Dong; K. Xiao; X.G. Li (pp. 631-639).

► Passive film of 2205 DSS in Na₂S₂O₃ solution has different composition. ► The potential effect semiconductor properties of passive film. ► The donor levels decrease exponentially with increasing film formation potential.The electrochemical behaviour of passive film formed on 2205 duplex stainless steel in 0.1M Na₂S₂O₃ solutions was investigated using potentiodynamic polarization, EIS, Mott–Schottky analysis and the compositions of oxide film in different passive regions were carried out by XPS. The results indicated that the impedance is dependent on the applied potential indicating the occurrence of a charge transfer reaction in a porous film. The doping densities evaluated from Mott–Schottky plots demonstrated that there existence of two donor levels in the space charge layer of the passive films. The donor density ( N D₁ and N D₂) values are in the range of 10²⁰–10²¹cm³, and decreases exponentially with increasing film formation potential, which is in good agreement with the theoretical consequences of the PDM. The polarization curve and XPS results shows that in the passive regions the 2205 duplex stainless steel exhibits different electrochemical and semiconductor properties.

Keywords: 2205 duplex stainless steel; Passive film; Sodium thiosulphate

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Applied Surface Science (v.258, #1)

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Applied Surface Science (v.258, #1)