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Applied Surface Science (v.258, #19)

In-plane ordered grain boundaries inducing enhanced magnetoresistance in epitaxial manganite films by Yunxin Han; Wenbin Wu; Guoshun Jiang; Changfei Zhu (pp. 7245-7249).

► La_5/8Ca_3/8MnO₃ films with in-plane ordered grain boundaries were epitaxially grown on the yttria-stabilized zirconia (111) single crystal substrates. ► Structures of films were clarified definitely by X-ray diffraction measurements and schematics. ► Large MR over a broad temperature range was confirmed due to in-plane ordered grain boundaries and coupled with the film thickness.La_5/8Ca_3/8MnO₃ (LCMO) films with [110]-orientation were epitaxially grown on yttria-stabilized zirconia (111) [YSZ (111)] single crystal substrates. The results of X-ray diffractions confirmed that these LCMO/YSZ films show in-plane ordered grain boundaries, which are attributed to the symmetry mismatch between the films and the substrates. It is striking that the films exhibit large magnetoresistance (MR) over a broad temperature range due to the grain boundary effects. The similar feature was observed in polycrystalline manganites. However, it should be noted that our samples are epitaxial in nature. These results indicate that this approach is promising for the fabrication of large area MR devices with controlled grain boundaries.

Keywords: PACS; 68.55.Jk; 68.35.Ct; 61.72.MmManganite film; Ordered grain boundaries; Spin-polarized

Comparative study of the influence of two distinct sulfurization ramping rates on the properties of Cu₂ZnSnS₄ thin films by Jie Ge; Yunhua Wu; Chuanjun Zhang; Shaohua Zuo; Jinchun Jiang; Jianhua Ma; Pingxiong Yang; Junhao Chu (pp. 7250-7254).

► The ramping rate of sulfurization of CZTS precursors with high Sn content has been studied. ► Fast ramping at 21°C/min resulted in the degraded CZTS films after sulfurization with a bubble-like surface. ► Slow ramping at 2°C/min can remove the excessive Sn in the films and elevate the crystalline quality of CZTS films.The Cu₂ZnSnS₄ (CZTS) are produced by sulfurization of precursors cosputtering from Cu₂Sn and ZnS targets at two distinct ramping rates (2°C/min and 21°C/min). Through the comparative analyses of scanning electron microscopy (SEM), energy dispersive of X-ray (EDS), X-ray diffraction (XRD), transmittance and Raman spectrum, it has been revealed that heating rate has a great impact on the reaction mechanism and characters of CZTS. The rapid heating rate 21°C/min has resulted in the appearance of bubble-like morphology and the concurrency of amorphous phases with CZTS. CZTS absorbers sulfurized at 2°C/min have exhibited a better crystallographic quality revealed by Raman spectroscopy and XRD pattern. However, XRD and transmittance have proved n-type SnS and Cu₄Sn₇S₁₆ phases concurrent with the slowly ramped CZTS films. Difference in the two ramping rates has also resulted in the variance of band gap and Raman primary mode of the final films. The slow sulfurization (2°C/min) superior to the rapid one (21°C/min) is beneficial to the growth of the expected CZTS in this work.

Keywords: Cu; ₂; ZnSnS; ₄; Thin film; Sputtering; Sulfurization; Ramping rate

Surface modification of tungsten carbide by electrical discharge coating (EDC) using a titanium powder suspension by Pichai Janmanee; Apiwat Muttamara (pp. 7255-7265).

► Surface modification of tungsten carbide by EDC using a Ti powder suspension. ► To eliminate micro-crack defects on the surface of tungsten carbide. ► Surface coating layer deposition can increase the hardness of the surface from 990HV to 1750HV.Surface modification by a titanium coating layer onto a tungsten carbide surface by electrical discharge coating (EDC) was studied by considering a titanium coating modification as well as the completeness of the tungsten carbide surface. This was carried out by electrical discharge machining (EDM). The tungsten carbide material was produced using a fluid dielectric oil, which was mixed with titanium powder. The current and duty cycles were varied resulting in a change in the titanium coating layer thickness. Also, an analysis of the chemical composition using energy dispersive spectroscopy (EDS) revealed that a titanium coating layer was formed causing the hardness of the titanium surface to be close to that of tungsten carbide. The completeness of the surface was evaluated using scanning electron microscopy (SEM) and a small number of microcracks were found on the surface since the microcracks were filled and substituted by titanium powder and carbon (a hydrocarbon) that decomposed from the dielectric that acted as a combiner (TiC). Also, the high concentration of carbon increased the amount of Ti and C combination and TiC was formed, which enhanced the surface hardness of the coated layer to 1750HV. The surface roughness of the coated layer decreased and this reduced the formation of microcracks on the surface workpiece.

Keywords: Surface modification; EDC; Titanium powder; WC–Co; Hardness; Microcracks

Numerical simulation of the unsteady non-linear heat transfer problems. Application on nanosecond laser annealing of Si by G.C. Bourantas; D.P. Korfiatis; V.C. Loukopoulos; K.-A.Th. Thoma (pp. 7266-7273).

► Numerical simulation of the unsteady non-linear heat transfer problems. ► A nanosecond Gaussian in time and space pulse. ► Meshfree point collocation method (MPC). ► Good agreement with analytical, numerical and experimental results presented in the literature.The aim of the present work is the numerical simulation of the unsteady non-linear heat transfer problems. A nanosecond Gaussian in time and space pulse is considered as the heat source acting on a Si substrate. Four different scenarios are considered in order to examine the influence of the laser parameters on the Si surface temperature, namely variation of the fluence of the laser beam, the radius of the laser beam at the Si surface, the duration of the pulse and finally the number of laser pulses. A meshfree point collocation method (MPC) has been employed for the solution of the problem. More precisely, the moving least squares (MLS) approximation is incorporated for the construction of the shape functions, in conjunction with the general framework of the point collocation method. The accuracy and stability of the proposed scheme are demonstrated through three representative benchmark problems in 1D, 2D and 3D. Numerical results are found to be in very good agreement with analytical, numerical and experimental results presented in the literature.

Keywords: Nanosecond laser; Unsteady non-linear heat transfer problems; Meshfree point collocation method

Influence of pulsed substrate bias on the structure and properties of Ti–Al–N films deposited by cathodic vacuum arc by G.P. Zhang; G.J. Gao; X.Q. Wang; G.H. Lv; L. Zhou; H. Chen; H. Pang; S.Z. Yang (pp. 7274-7279).

► It showed that the films exhibited NaCl-type fcc structure. With the increase substrate bias the microstructure of the films changed from random orientation to (100) and (220) texture. ► The Ti/(Ti+Al) atomic ratio gradually increased from 43% to 52% with an increase of bias voltage. ► The nanohardness, friction coefficient and Lc approach highest values of 39GPa, 0.36 and 75N respectively. ► It was found that ideal mechanical properties of films can be obtained with medium substrate bias voltage.Ti–Al–N films were deposited by cathodic vacuum arc (CVA) technique in N₂ atmosphere with different pulsed substrate bias. The influence of pulsed substrate bias (0 to −800V) on the deposition rate, surface morphology, crystal structure, and mechanical properties of the Ti–Al–N films were systematically investigated. Increasing pulsed bias voltage resulted in the decrease of deposition rate but the increase of surface roughness. It was found that there was a strong correlation between the pulsed bias and film structure. All the films studied in this paper were composed of TiN, AlN, and Ti–Al–N ternary phases. The grains changed from equiaxial to columnar and exhibited preferred orientation when the pulsed bias increased. With the increase of pulsed bias voltage, the atomic ratio of Ti to Al element increased gradually, while the N to (Ti+Al) ratio decreased. The composite films present an enhanced nanohardness compared with binary TiN and ZrN films. The film deposited with pulsed bias of −200V possessed the maximum scratch critical load and nanohardness. The minimum friction coefficient with pulsed bias of −300V was obtained.

Keywords: Ti–Al–N films; Pulsed bias; Cathodic vacuum arc

Very large-bandgap insulating monolayers of ODS on SiC by Nabi Aghdassi; Dorothea Dulson; Steffen Linden; Liqiang Li; Lifeng Chi; Helmut Zacharias (pp. 7280-7285).

► Homogeneous ODS monolayers are prepared on 6H-SiC(0001). ► HOMO–LUMO gap of about 9eV is determined by UPS and IPE. ► Large barrier heights of about 3eV for charge transport from substrate to adsorbate are evidence for effective electronic passivation of SiC substrate. ► Time evolution of IPE spectra elucidates origin of ODS LUMO peak.In the present work we describe the electronic properties of octadecylsiloxane (ODS) adsorbed on 6H-SiC(0001). A quantitative analysis of the C 1s region of the functionalized samples by X-ray photoelectron spectroscopy (XPS) revealed a surface coverage of about one monolayer. The highest occupied molecular orbital (HOMO) of the organic film is located about E_b=−5.3eV below the Fermi level as determined by ultraviolet photoemission spectroscopy (UPS). Inverse photoemission (IPE) determined the energetic position of the lowest unoccupied molecular orbital (LUMO) about E_u=3.7eV above the Fermi level. Thus the HOMO–LUMO energy gap is determined to about 9eV for the present system. A comparison between the respective electronic states of the substrate and the adsorbate revealed barrier heights for charge transport from the substrate into the adsorbate, 3.3eV and 2.7eV for electrons and holes, respectively. The time evolution of the collected IPE spectra indicates that the LUMO is mainly attributed to antibondingσSiC∗ bonds.

Keywords: Silicon carbide; Semiconductor–organic interface; Self-assembled monolayer; Electronic passivation; Inverse photoemission

Corrosion and ion release behavior of Cu/Ti film prepared via physical vapor deposition in vitro as potential biomaterials for cardiovascular devices by Hengquan Liu; Deyuan Zhang; Feng Shen; Gui Zhang; Shenhua Song (pp. 7286-7291).

► Various Cu/Ti ratio films were prepared. ► Anti-endothelialization is related to Cu²⁺ concentration. ► Electrochemical property was studied. ► Cu²⁺ release are investigated.Cu/Ti films of various Cu/Ti ratios were prepared on a TiNi alloy via vacuum arc plasma deposition. The phase composition, structure, and concentration of elements were investigated via X-ray diffraction and X-photoelectron energy spectrum. The hemolysis ratio and platelet adhesion of the different films were characterized to evaluate blood compatibility. The corrosion and ion release behavior were investigated via a typical immersion test and electrochemical method. The growth of endothelial cells (ECs) was investigated, and methylthiazolyte-trazolium method was employed to evaluate the effect of Cu²⁺. The sophisticated films showed good compatibility. However, with increasing quality ratio of Cu/Ti, the hemolysis ratio increased, and some platelets started to break slightly. The Cu²⁺ release was gradually stabilized. The open circuit potential of the Cu/Ti film-modified samples was lower than that of the TiNi substrate. The polarization test result indicates that the passivation stability performance of Cu/Ti film samples is less than the TiNi substrate, and is favorable to Cu²⁺ release. The adhesion and proliferation of ECs would be inhibited with 10wt.% Cu concentration of the film, and ECs would undergo apoptosis at >50wt.% concentration. A Cu/Ti film with good compatibility and anti-endothelialization has potential applications for special cardiovascular devices.

Keywords: Cu/Ti film; Ion release; Blood compatibility; Endothelialization

On the surface characterization of an Al₂O₃ charge state conversion surface using ion scattering and atomic force microscope measurements by A. Riedo; M. Ruosch; M. Frenz; J.A. Scheer; P. Wurz (pp. 7292-7298).

► Thermal certification campaigns on charge state conversion surfaces were performed. ► Ion scattering and AFM instruments were used to characterize surface properties. ► AFM images showed no significant changes in surface roughness. ► Ion scattering instrument was sensitive enough to measure changes on sub atomic level.Thermal certification campaigns in the temperature ranges of −50°C to +85°C and −70°C to +130°C on charge state conversion surfaces (aluminum-oxide coatings on a silicon wafer substrate) were performed. Such surfaces are often used in neutral particle sensing instruments in space science where neutral atoms must be ionized prior to their analysis. Ion scattering and atomic force microscope (AFM) instruments were used to characterize the surface properties, e.g., surface roughness, angular scattering distribution and negative ionization efficiency of charge state conversion surfaces before and after thermal certification campaigns. No significant changes in surface roughness were found in AFM images whereas ion scattering measurements revealed a significant increase of the angular scattering distribution of up to 21% after thermal campaign in the expanded temperature range of −70°C to +130°C. The present study shows clearly that ion scattering measurements are sensitive enough to measure surface changes on atomic and sub atomic level whereas at this level the AFM instrument finds its limits.

Keywords: Ion scattering; AFM; Measurement sensitivity; Charge state conversion surface; Surface characterization; Space application

High adsorption capacity of V-doped TiO₂ for decolorization of methylene blue by Thanh-Binh Nguyen; Moon-Jin Hwang; Kwang-Sun Ryu (pp. 7299-7305).

Display Omitted► TiO₂ is applied widely in environment because of its advantage. ► However, adsorption capacity of TiO₂ is low for most adsorbates. ► Improving performance of TiO₂, V-doped TiO₂ was fabricated by new sol–gel method. ► Adsorption capacity of V-doped TiO₂ was increased significantly to 11.36 times.In this study, pure TiO₂ (V-TiO₂-0) and V-doped TiO₂ (V-TiO₂- x, x=1–10mol%) were synthesized using a new sol–gel method. The adsorption capacity of the V-TiO₂- x samples was evaluated by measuring the removal of methylene blue (MB) from aqueous solution via decolorization. Since the adsorption capacity was affected by the specific surface area, the interaction between adsorbate (MB) and adsorbent (V-TiO₂- x), and the structure of the adsorbent, the physicochemical properties of the samples were investigated. Among the V-doped TiO₂- x samples, the V-TiO₂-10 sample showed the highest adsorption capacity, which was 11.36 times greater than that of pure TiO₂, removing 85.2% of the MB after 2h. Moreover, changing the molar ratio of the reactants in the V-TiO₂-10 sample improved the performance of the material so that 91.6% of the MB was removed after 2h.

Keywords: Adsorption; Metal ion-doped TiO; ₂; Mesoporous; Decolorization; Methylene blue

Structural and mechanical analysis for the optimization of PVD oxide coatings for protection against metal dusting by L.M. López; O. Salas; L. Melo-Máximo; J. Oseguera; C.M. Lepienski; P. Soares; R.D. Torres; R.M. Souza (pp. 7306-7313).

► Cr-oxide thin films were investigated as protective coatings against metal dusting. ► Amorphous Cr₂O₃ formed and resulted in low values of hardness and elastic modulus. ► Bias voltage produced the most remarkable and beneficial effect for the application. ► Non-biased, graded and non-graded, films developed tensile residual stresses.The evolution of the structure and properties of Cr/Cr oxide thin films deposited on HK40 steel substrates by reactive magnetron sputtering (RMS) was investigated and linked to their potential protective behavior against metal dusting. Deposition time, mode of oxygen feeding, and application of bias voltage were varied to assess their effect on the density, adhesion, and integrity of the films. All the films showed a very fine columnar microstructure and the presence of amorphous Cr oxide. Both, an increasing time and a constant oxygen flow during deposition led to the development of relatively low density films and mud-like cracking patterns. A graded oxygen flow resulted in films with fewer cracks, but a careful control of the oxygen flow is required to obtain films with a truly graded structure. The effect of the bias voltage was much more significant and beneficial. An increasing negative bias voltage resulted in the development of denser films with a transition to an almost crack-free structure and better adhesion. The amorphous oxide resulted in low values of hardness and Young's modulus.

Keywords: Metal dusting; Protective films; Reactive magnetron sputtering; Film cracking; Nanoindentation

Growth and characterization of Ta/Ti bi-layer films on glass and Si (111) substrates by direct current magnetron sputtering by Y.M. Zhou; Z. Xie; Y.Z. Ma; F.J. Xia; S.L. Feng (pp. 7314-7321).

► The titanium adhesion layer surface characteristic plays a remarkable influence on the structural and electrical properties of the sputter deposited Ta films. ► The adhesion layer of titanium without breaking vacuum always promote the tantalum films to grow with the orientation following that of the bottom titanium layer and nucleate bcc α phase of tantalum. ► The underlying titanium film with exposure its surface to atmosphere for 24h would restrain the nucleation of α-Ta and promote the growth of β-Ta. ► The mechanism explains the difference of the growth mode of the tantalum films.The influence of a sputter-deposited titanium adhesion layer on glass and Si (111) substrates with or without exposure of titanium layer surface to the atmosphere on the growth mode of the tantalum films was studied. It was found that, because of the well match of the cell constants between the deposited Ta and the underlying Ti, the tantalum films continuously deposited on the adhesion layer of titanium grown without breaking vacuum always grew with the orientation following that of the bottom titanium layer and nucleated bcc α phase of tantalum with low degrees of orientation. After exposure of the bottom titanium layer surface to atmosphere, the absorption and diffusion of oxygen and other impurity atoms on the surface would promote a higher lever of oxidation and favor to form more and more titanium suboxides at the Ti surface. The increase of titanium suboxides at the Ti surface change the lattice mismatch between the underlying titanium film and the bcc-Ta film, which disturbed the nucleation of α-Ta and promoted the growth of β-Ta. Consequently, the electrical properties of the Ta/Ti bi-layer films were significantly changed.

Keywords: Thin films; Tantalum; Titanium; Crystal orientation; Sputtering

Well-ordered arranging of Ag nanoparticles in SiO₂/Si by ion implantation by K. Takahiro; Y. Minakuchi; K. Kawaguchi; T. Isshiki; K. Nishio; M. Sasase; S. Yamamoto; F. Nishiyama (pp. 7322-7326).

► Well-ordered arrangements of Ag nanoparticles have been observed. ► A δ-layer of tiny Ag nanoparticles was aligned along the SiO₂/Si interface. ► A two-dimensional array of Ag nanoparticles of 25–40nm was also formed. ► The Ag nanoparticles in SiO₂ were quite stable against oxidation and sulfidation.Well-ordered arrangements of Ag nanoparticles have been found for Ag-implanted SiO₂ at depths corresponding to the projected range and end of range of Ag ions. Thermally grown SiO₂ films of 300nm thick on Si were implanted with 350keV-Ag ions to fluences of 0.37–1.2×10¹⁷ions/cm² at a current density about 4μA/cm². Cross-sectional transmission electron microscopy and scanning transmission electron microscopy reveal the presence of a two-dimensional array of Ag nanoparticles of 25–40nm in diameter located at a depth of ∼130nm, together with the self-organization of δ-layer of tiny Ag nanoparticles aligned along the SiO₂/Si interface. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) confirm the stability of these Ag nanoparticles against oxidation and sulfidation when stored in ambient air for 19–21 months.

Keywords: Ion implantation; Nanoparticle; 2D array; Interface; δ-Layer; Oxidation; Sulfidation

Fabrication of copper nanoparticles/graphene oxide composites for surface-enhanced Raman scattering by Kailong Zhang (pp. 7327-7329).

► Cu/graphene oxide (GO) composites were synthesized by a facile and effective polymer-assisted chemical reduction method. ► The Cu nanoparticles homogeneously distributed on GO nanosheets. ► The synthetic Cu/GO composites have been demonstrated to be potentially a new type of SERS substrates.Cu/graphene oxide composites were synthesized by a facile and effective chemical reduction method. The resulting Cu/graphene oxide(GO) composites were characterized by scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray diffraction. The performance of the Cu/GO composites as surface-enhanced Raman scattering (SERS) active substrate was evaluated via using 4-aminothiophenol (4-ABT) as the probe molecule. Compared with 4-ABT on Cu nanoparticles film, the SERS signal of 4-ABT was obviously improved on the Cu/GO composites. The determination of 4-ABT in aqueous solution with SERS method at the Cu/GO composite displayed a line range from 10⁻⁸ to 10⁻⁴M. The present methodology demonstrates that the composite film composed of Cu, GO is potential for optical chemical sensor applications.

Keywords: Composite materials; Graphene oxide

Laser-induced voltage effects in c-axis inclined Na_xCoO₂ thin films by Shufang Wang; Shanshan Chen; Fuqiang Liu; Guoying Yan; Jinchun Chen; Huiling Li; Jianglong Wang; Wei Yu; Guangsheng Fu (pp. 7330-7333).

► The laser-induced voltage effects in c-axis inclined Na_xCoO₂ thin films were studied. ► Transverse voltage signals are all observed when the film surface is irradiated by different laser sources. ► Giant transverse voltages of tens of volts are detected when the film surface is irradiated by the UV pulsed laser. ► The c-axis inclined Na_xCoO₂ thin film has a great potential application in the weak UV pulsed laser detection.Laser-induced voltage effects in c-axis inclined Na_xCoO₂ thin films have been studied by using different laser sources with the wavelength ranging from ultraviolet to far infrared. Due to the transverse thermoelectric effect, a giant open-circuit voltage signal with the peak voltage V_p of about 16V is detected when the film surface is illuminated by an ultraviolet 308nm pulsed laser with the laser energy on the film is about 1.5mJ. Open-circuit voltage signals are also detected when the film is illuminated by the 532nm and 10.6μm lasers. The results demonstrate that the c-axis inclined Na_xCoO₂ thin film has a great potential application in the detection of laser radiations for wide spectral range, especially in the weak ultraviolet pulsed laser detection.

Keywords: Laser-induced voltage; Na; _x; CoO; ₂; thin films; Transverse thermoelectric effect

Periodic DFT study of adsorption of nitroamine molecule on α-Al₂O₃(001) surface by Su-Qin Zhou; Xue-Hai Ju; Feng-Qi Zhao; Si-Yu Xu (pp. 7334-7342).

► Adsorption of nitroamine on α-Al₂O₃(001) surface was investigated by density functional theory method. ► Aluminized explosive of NH₂NO₂ keeps high reactivity even if the aluminum is oxidized to form a film of the alumina. ► The energies of DOS for N and O atoms of the NH₂NO₂ molecule match with those of Al atoms, and AlO or AlN bond forms easily at the corresponding energies range. ► The Al atom on the alumina surface binds with the nitro O atom due to the ionicity of Al₂O₃. ► The adsorption energies are in range of −350.2 to −453.8kcalmol⁻¹.The adsorption of NH₂NO₂ molecule on the Al₂O₃(001) surface were investigated by the generalized gradient approximation (GGA) of density functional theory (DFT). The calculations employ a supercell model represented with 2×2 of periodic boundary conditions. The strong attractive forces between NH₂NO₂ molecule and Al₂O₃ induce obvious change of the NH₂NO₂ and Al₂O₃ structure. Although the NH₂NO₂ molecule does not decompose, AlO bonds partially decompose and some OO bonds form, whose bond lengths are intervenient between OO double bond length and OO single bond length. The largest adsorption energy is −453.8kcalmol⁻¹. By the adsorption energy and the change with structure of NH₂NO₂ and Al₂O₃, it can be concluded that aluminized explosive of NH₂NO₂ keeps high reactivity even if the aluminum is oxidized to form a film of the alumina. This finding can make clear the activated aluminum as a stored energy source for propellants and the good performance of aluminized explosives. The energies of DOS for N and O atoms of the NH₂NO₂ molecule match with those of Al atoms, and AlO or AlN bond forms easily at the corresponding energies range. The DOS projections on the N, O and Al atoms occur with obvious shift of peaks, which infers energy bands become broad and the interactions of chemical bonds are strengthened.

Keywords: NH; ₂; NO; ₂; Al; ₂; O; ₃; (0; 0; 1); Adsorption; Density functional theory

Controllable synthesis, characterization and photoluminescence properties of morphology-tunable CdS nanomaterials generated in thermal evaporation processes by Zai-Xing Yang; Wei Zhong; Peng Zhang; Mei-Hua Xu; Yu Deng; Chak-Tong Au; You-Wei Du (pp. 7343-7347).

High-quality and uniform CdS (a) nanobelts, (b) nanowires, and nanorods (both straight (c) and curved (d)) have been fabricated through thermal evaporation processes.Display Omitted► The approach is low-cost and the generation of product is highly reproducible. ► In the VLS processes, the content of Cd has a crucial effect on CdS nanomaterials. ► The CdS nanomaterials can be utilized in the industry of optoelectronic nanodevices. ► CdS nanomaterials obtained by regulating CdS to Cd ratio have never been reported.High-quality CdS nanomaterials were fabricated through thermal evaporation of a mixture of CdS and Cd powders at 650°C and at an Ar carrier gas flow of 20sccm (standard cubic centimeters per minute). They were in the forms of nanoparticles, nanobelts, nanowires, and nanorods (both straight and curved). The hexagonal wurtzite phase of the CdS nanomaterials was verified by XRD, and their single crystallinity confirmed by selected area electron diffraction. As revealed in field emission scanning electron microscope (FESEM) and TEM analysis, CdS nanobelts, nanowires, and nanorods can be obtained by regulating the CdS-to-Cd ratio. A mechanism for the growth of the CdS nanomaterials has been described. In the study, we investigated the optical nature of the CdS nanomaterials and observed that the CdS nanomaterials showed good photoluminescence (PL) properties. The CdS nanobelts and nanorods were similar in PL peaks whereas the CdS nanowires showed no sight of DL emission.

Keywords: Nanostructured materials; Semiconductors; Crystal growth; Vapor deposition; Crystal structure; Luminescence

Microstructural study of surface melted and chromium surface alloyed ductile iron by M. Heydarzadeh Sohi; M. Ebrahimi; H.M. Ghasemi; A. Shahripour (pp. 7348-7353).

► Ductile iron was surface melted and chromium surface alloyed by tungsten inert gas process. ► Chromium surface alloying was carried out by pre-placing of ferrochromium powder. ► Microstructure and hardness of the surface melted and alloyed layers were studied. ► Hardness of the melted and alloyed layers reached to around 3.3 and 4.9 times of that of the base material, respectively.In this study, ductile iron was surface melted and chromium surface alloyed via pre-placing of ferrochromium powder with different thicknesses and subsequently surface melting by tungsten inert gas (TIG) process. Optical and scanning electron microscopy, as well as micro-hardness testing and X-ray diffraction analysis were used for characterization of the treated samples. Surface melting and chromium surface alloying resulted in formation of ledeburitic structure and high chromium white cast iron in the treated layers, respectively. It was also noticed that hardness of the treated layers was considerably higher than that of the base material. Increasing thickness of ferrochromium layer increased the amount of M₇C₃ carbides and hardness of the alloyed layer.

Keywords: TIG; Ductile iron; Surface melting; Chromium surface alloying

Comparative study of potassium hexatitanate (K₂Ti₆O₁₃) whiskers prepared by sol–gel and solid state reaction routes by Mohd Asim Siddiqui; Vishal Singh Chandel; Ameer Azam (pp. 7354-7358).

► K₂Ti₆O₁₃ whiskers are prepared through sol–gel (PSG) and by solid state reaction route (PSS). ► K₂Ti₆O₁₃ (PSG) exposing nanorods while K₂Ti₆O₁₃ (PSS) reveals microrods. ► Dielectric constant and loss tangent are found to be high for PSG as compare to PSS. ► The energy band gap is found to be higher for the sample prepared by sol–gel method. ► Photocatalytic activity is found, better for the sample prepared by sol–gel method.Polycrystalline phases of the potassium hexatitanate (K₂Ti₆O₁₃) were synthesized by conventional solid state reaction and sol–gel methods with a view to compare structural, electrical, optical and photocatalytic properties. Single phase K₂Ti₆O₁₃ prepared by sol–gel method (PSG) revealed higher value of dielectric constant than same obtained by the solid state reaction method (PSS), attributed to smaller particle size in sol–gel method. Band gap (3.48eV) of K₂Ti₆O₁₃ prepared by sol–gel method was found higher than (3.06eV), obtained in solid state reaction method. Additionally, K₂Ti₆O₁₃ was tested as photocatalyst on the degradation of methyl orange (MO) under UV light and found better activity for sample PSG. Morphological characteristic exhibited formation of nanorods in sol–gel route and formation of microrods in solid state reaction method.

Keywords: Potassium hexatitanate; Sol–gel; Dielectric constant; Band gap; Photocatalytic

Fabrication of chitosan–CdSe/CdS/ZnS multilayer films by electrostatic self-assembly method by Fenghua Huang; Xia Lin; Chen Cheng; Peifeng Chen (pp. 7359-7364).

► The CdSe/CdS/ZnS nanocrystals with good fluorescence properties were synthesized in aqueous solution by usingl-cysteine as stabilizer. ► The multilayer films of chitosan–CdSe/CdS/ZnS with good quality were fabricated by layer-by-layer electrostatic self-assembly method. ► The ultrathin multilayer films of chitosan–CdSe/CdS/ZnS show good fluorescence property.Thel-cysteine-modified CdSe/CdS/ZnS nanocrystals were synthesized in aqueous solution by usingl-cysteine as stabilizer. The chitosan–CdSe/CdS/ZnS ultrathin multilayer films were fabricated on the pretreated quartz substrate by layer-by-layer electrostatic self-assembly method. The CdSe/CdS/ZnS nanocrystals were characterized by X-ray power diffraction (XRD), fluorescence spectrum and UV–vis spectrum. The UV–vis spectrum, fluorescence spectrum, IR spectrum, contact angle analysis and atomic force microscope analysis were used to characterize the chitosan–CdSe/CdS/ZnS ultrathin multilayer films. The results indicate that chitosan and CdSe/CdS/ZnS nanocrystals are alternatively deposited on the quartz surface, resulting in the buildup of a high quality chitosan–CdSe/CdS/ZnS multilayer films. The prepared ultrathin films of chitosan–CdSe/CdS/ZnS show good fluorescent property, which have potential application in biosensor.

Keywords: CdSe/CdS/ZnS; Chitosan; Electrostatic self-assembly; Multilayer films

Preparation of (Ba,Sr)TiO₃@polystrene core-shell nanoparticles by solvent-free surface-initiated atom transfer radical polymerization by Yang Xiaowei; Zeng Yanwei; Cai Tongxiang; Hu Zhenxing (pp. 7365-7371).

The polystyrene shells were successfully grown on the BST nanocrystals, synthesized by microwave-activated glycothermal method, via a solvent-free surface-initiated atom transfer radical polymerization after an appropriate surface functionalization of nanocrystals.Display Omitted► The PS shells have been successfully grown on the BST nanocrystals via an ATRP approach. ► The BST nanocrystals with modified surfaces act as macroinitiators for ATRP to yield core-shell structure. ► The PS shell can reach ∼10nm in thickness when the polymerization time is extended to 36h.The polystyrene shells have been successfully grown on the barium strontium titanate (BST) nanocrystals, which were synthesized by microwave-activated glycothermal method, via a solvent-free surface-initiated atom transfer radical polymerization (SI-ATRP) after the 2-bromo-2-methylpropionic acid molecules (Br-MPA) were anchored at the surface of BST nanocrystals through ligand exchange with hydroxyl groups on their surfaces. These surface modified BST nanocrystals can then be perfectly dispersed in styrene monomer and act as macroinitiators for ATRP to yield BST@PS core-shell structured nanoparticles, which endow the BST nanocrystals with exceptionally good dispersibility and stability in hydrophobic solvents. The BST@PS core-shell structures were characterized by X-ray diffraction (XRD) technique and transmission electron microscopy (TEM). Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (Raman), differential scanning calorimetry (DSC) and gel permeation chromatography were also employed to probe the Br-MPA and PS on the BST nanocrystals. It has been shown that after the BST nanocrystals are surface-modified with Br-MPA, the polymerization of styrene can steadily occur at the surface of BST nanocrystals to form a uniform polystyrene shell and its thickness can reach ∼10nm when the polymerization reaction is extended to 36h, while no changes are found to take place with the BST nanocrystals. Compared with typical high molecular weight PS ( M_n=6700), the as-obtained PS possess a relatively low molecular weight ( M_n=5473) and a lower glass transition temperature ( T_g∼93°C). The research results demonstrate a viable strategy for the preparation of polymer-coated functional metal oxides nanocrystals, potentially useful in biological and nanoelectronic applications.

Keywords: Atom transfer radical polymerizations (ATRP); Barium strontium titanate (BST); Polymer-coated functional oxide nanocrystals; Core-shell structure

Interference of the surface plasmon polaritons with an Ag waveguide probed by dual-probe scanning near-field optical microscopy by R. Fujimoto; A. Kaneta; K. Okamoto; M. Funato; Y. Kawakami (pp. 7372-7376).

► We observe nanoscale behaviors of surface plasmon polaritons using dual-probe scanning near-field optical microscopy. ► We find interferences of surface plasmon polaritons only in a waveguide structure with a certain width. ► Reflective waves at side edges cause interferences, which are also confirmed from theoretical calculations.The propagation of surface plasmon polaritons (SPPs) on Ag waveguides with two different widths is directly observed using dual-probe scanning near-field optical microscopy (DSNOM). We find that the waveguide structure strongly affects the propagation of locally excited SPPs. SPPs in a flat plane structure spread radially, whereas SPPs in a 3.4-μm wide waveguide structure form two-dimensional interference fringes due to the multiple reflections at the side edges. The experimental results agree well with finite-difference time-domain calculations. The results suggest that the DSNOM technique can visualize the nanoscale characteristics of the SPP waves in various plasmonic waveguides.

Keywords: Surface plasmon polaritons; Dual-probe scanning near-field optical microscope; Interferences; Finite-difference time-domain calculations

Mass transfer in “metal layer–silicon substrate” systems under the action of compression plasma flows by V.V. Uglov; R.S. Kudaktsin; Yu.A. Petukhou; N.T. Kvasov; A.V. Punko; V.M. Astashynski; A.M. Kuzmitski (pp. 7377-7383).

► Redistribution of metal and silicon are studied experimentally by SEM and AES. ► Mechanisms of diffusive and convective heat and mass transfer are simulated. ► The formation of deep melt layer is caused mainly by non-uniformity of plasma flow. ► The proposed model gives treatment modes to form layers with controlled composition.Redistribution of components in surface layers of “metal-on-silicon” system under the action of compression plasma flows (CPF) with energy density 3–16J/cm² are studied experimentally by SEM, AES. Mechanisms of heat and mass transfer are simulated by numerical solving of heat and mass transfer equations. The suggested model of mass transfer takes into account convective motion in the melt surface layer and temperature dependence of substance parameters. It provides dependence of metal penetration depth and its concentration on CPF energy density and convection velocity. Results of simulations are in accordance with experimental data; therefore, the proposed model enables to choose appropriate treatment modes for the formation of metal-doped silicon layers with controlled thickness and elemental composition.

Keywords: Silicides; Compression plasma flows; Diffusion; Convection

Synthesis of colourless silver precursor ink for printing conductive patterns on silicon nitride substrates by Qijin Huang; Wenfeng Shen; Weijie Song (pp. 7384-7388).

► A stable and colourless silver precursor ink has been synthesised for directly printing silver conductive patterns with a common colour ink-jet printer. ► The resistivity of silver conductive films deposited using 20 printing cycles was 3.1μΩcm, which was twice as high as that of bulk silver. ► The low resistivity of silver patterns suggests applications for ink-jet printing of electronics devices.Silver precursor ink was synthesised by a simple and environmentally friendly method based on chemical reduction. The stability, particle size, viscosity and surface tension of the ink were adjusted by adding polyvinylpyrrolidone (PVP) and ethylene glycol (EG). The silver patterns were fabricated on the silicon nitride substrate and were characterised by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrical measurements. The thickness of the sample printed three times was approximately 0.66μm, and it increased to 2.43μm after 12 printings. The ink-jet-printed silver patterns exhibited good conductivity when the samples were sintered at temperatures above 200°C. The resistivity value was observed to decrease to 3.1μΩcm after sintering at 500°C for 60min, twice the value of bulk silver (1.6μΩcm). The low resistivity of silver patterns suggests applications for ink-jet printing of electronics devices.

Keywords: Ink-jet printing; Silver precursor ink; Conductive silver patterns

Cadmium(II) and lead(II) adsorption onto hetero-atom functional mesoporous silica and activated carbon by Motoi Machida; Babak Fotoohi; Yoshimasa Amamo; Louis Mercier (pp. 7389-7394).

► Amino-functionalized silica exhibited the best adsorption for Cd(II) and Pb(II). ► Selective adsorption of Cd(II) might be achieved by mercapto-functionalized silica. ► Wider solution pH can be used for carboxylic-functionalized activated carbon and mercapto-silica.Adsorption of cadmium(II) and lead(II) on amino-, mercapto-functionalized mesoporous silica (HMS) and carboxylic-functionalized activated carbon (AC) were examined. The resultant isotherms fitted the Langmuir model and amino-functionalized HMS exhibited the highest adsorption capacity for both cadmium(II) and lead(II). Adsorption affinities for cadmium(II) were always greater than those for lead(II) in all three adsorbent types, while the difference between the two values was the largest for mercapto-functionalized HMS indicating a selective adsorption of cadmium(II). Influence of equilibrium solution pH on adsorption of cadmium(II), lead(II) and their binary mixtures was also studied. Carboxylic-functionalized AC adsorbed cadmium(II) and lead(II) in a wide pH range than conditions for the mercapto-functionalized HMS. It was concluded that each functional group had its own characteristics and advantages for adsorption of heavy metal ions; amino-groups showed high adsorption capacity, while mercapto-groups had good selectivity toward cadmium(II) adsorption and a wide solution pH in adsorption by carboxylic-groups were established in this study.

Keywords: Heavy metals; Cadmium; Lead; Mesoporous silica; Activated carbon; Adsorption

Raman and TEM characterization of high fluence C implanted nanometric Si on insulator by R.M.S. dos Reis; R.L. Maltez; E.C. Moreira; Y.P. Dias; H. Boudinov (pp. 7395-7400).

► We synthesized 30–40nm SiC layers by C implantation at 600°C and 1250°C annealing. ► C region Raman spectra (1100–1700cm⁻¹) reveal CC bounds in the layer. ► Raman in the C region can probe structural quality; SiC bounds showed weak signal. ► Two parameters were defined for the analysis and agreed about the conclusions. ► Direct analysis by TEM demonstrated the reliability of the defined Raman parameters.In this work we present Raman and transmission electron microscopy (TEM) characterization of high fluence C implanted nanometric silicon on insulator. The analyzed samples were 35 and 60nm top layers of Si, which were entirely converted into SiC layers by 2.3×10¹⁷cm⁻² and 4.0×10¹⁷cm⁻² carbon implantations. We report the behavior of CC signal from Raman spectra for such overall Si to SiC conversions before and after 1250°C annealing. A remarkable effect is observed in the region of C signal (1100–1700cm⁻¹), where fitting with Lorentzian curves reveals that there are different types of CC bonds. Raman spectroscopy in this region was then employed to relatively characterize the SiC structural quality. TEM measurements support our Raman interpretation by direct structural evaluation of the formed SiC layers.

Keywords: PACS; 68.55.ag; 85.40.Ry; 78.30.Hv; 68.37.Lp; 61.37.OgC implantation; SiC layer on insulator; Ion beam synthesis; Raman spectroscopy; TEM

The fabrication of CoPt nanowire and nanotube arrays by alternating magnetic field during deposition by H.R. Liu; Q.F. Lu; X.F. Han; X.G. Liu; B.S. Xu; H.S. Jia (pp. 7401-7405).

► Regular CoPt nanowire and nanotube arrays was prepared. ► Different external magnetic field exhibits obvious influence on the magnetic properties of CoPt nanowire and nanotube. ► The influence of magnetic properties by external magnetic field have been discussed.Ordered CoPt nanowire (NWs) and nanotube (NTs) arrays were fabricated in anodic aluminum oxide template, their crystallographic structure and magnetic properties, during the progress of electrodeposition in applied external magnetic field, were investigated by X ray diffraction (XRD) and vibrating sample magnetometer (VSM). The XRD result shows that the CoPt face centered cubic (fcc) phase was dominant for all samples, while, the preferred crystal growth was influenced by external magnetic field. For CoPt NWs, with the increase of external magnetic field, coercivity (Hc_∥ and Hc_⊥) increased and the easy axis kept parallel with nanowire axis. On the other hand, for CoPt NTs, with increase of external magnetic field, Hc_∥ increased and Hc_⊥ decreased_. When the NTs were electrodeposited in external magnetic field parallel to template, the easy axis kept perpendicular to nanotube axis; However when external magnetic field was perpendicular to template, the easy axis of magneto-electrodeposited NTs changed from being perpendicular to tube axis to being parallel with tube axis. The change of effective magnetic anisotropy was explained by the competition between magnetocrystalline anisotropy and shape anisotropy.

Keywords: PACS; 81.07.De; 81.15.Pq; 78.30.Hv; 75.75.−c; 61.46.NpKeyword; Nanowires; Nanotubes; External magnetic field; Magnetic properties

Chemical states and optical properties of thermally evaporated Ge–Te and Ge–Sb–Te amorphous thin films by S. Kumar; D. Singh; S. Shandhu; R. Thangaraj (pp. 7406-7411).

► Thermally evaporated amorphous GeTe and Ge₂Sb₂Te₅ thin films. ► Sample characterization with XRD, XPS, EPMA, UV–vis–NIR and temperature dependent sheet resistance. ► Role of Sb was to suppress the formation of wrong homopolar bonds in GST system. ► Band gap, sheet resistance and phase transition temperature decreases while reflectivity and refractive index increase for GST than GT films. ► GST film was more absorptive than GT film for whole studied wavelength range.Thin amorphous films of Ge₂₂Sb₂₂Te₅₆ and Ge₅₀Te₅₀ have been prepared from their respective polycrystalline bulk on glass substrates by thermal evaporation technique. The amorphous nature of the films was checked with X-ray diffraction studies. Amorphous-to-crystalline transition of the films has been induced by thermal annealing and the structural phases have been identified by X-ray diffraction. The phase transformation temperature of the films was evaluated by temperature dependent sheet resistance measurement. The chemical structure of the amorphous films has been investigated using X-ray photoelectron spectroscopy and the role of Sb in phase change Ge₂₂Sb₂₂Te₅₆ film is discussed. Survey and core level (Ge 3d, Te 3d, Te 4d, Sb 3p, Sb 3d, O 1s, C 1s) band spectra has been recorded and analyzed. For optical studies, the transmittance and the reflectance spectra were measured over the wavelength ranges 400–2500nm using UV–vis–NIR spectroscopy. The optical band gap, refractive index and extinction coefficient are also presented for thermally evaporated amorphous thin films.

Keywords: Chalcogenide; Amorphous semiconductors; Chemical state; XPS

Ferroelectric domain switching investigation of BiFeO₃ thin film on Pt/Ti/SiO₂/Si (111) substrate by Fei Fan; Bingcheng Luo; Mengmeng Duan; Hui Xing; Kexin Jin; Changle Chen (pp. 7412-7416).

► The original ferroelectric domains was dominantly upward. ► The upward swiching of ferroelectric domains was harder than downward one. ► An unsymmetric ferroelectric hysteresis loop. ► The grain boundary and domain displacement/creation restrict the domain switching.The ferroelectric domain structure and polarization switching of the BiFeO₃ thin film deposited on Pt/Ti/SiO₂/Si(111) substrate using rf magnetron sputtering technique were studied by piezoelectric force microscopy. The initial domains were dominanted by the upward polarization state in our sample. The positive and negative dc biases switched the ferroelectric domains downward and upward, respectively; and the upward switching was more difficult than the downward one, demonstrating an unsymmetric ferroelectric hysteresis loop in our sample. The electric field dependent experiments were carried out to understand the evolution of the domain switching, and the obvious change in phase image was obtained only when poling at +10V, which implied the poling was performed close to the coercive field. The uncomplete domain switching was attributed to the unsufficient bisas, the impurity defect and the strain conditions as the result of ferroelastic domain displacement/creation.

Keywords: Multiferroic materials; Piezoelectric force microscopy; Ferroelectric domain switching

Studies on morphological and magnetic properties of La1−_xSr_xMnO₃ by K.P. Shinde; S.S. Pawar; P.M. Shirage; S.H. Pawar (pp. 7417-7420).

► LSMO have been synthesized by simple combustion technique. ► Structural analysis confirms the formation of rhombohedral crystal structure of LSMO. ► Nanocrystalline nature confirmed by transmission electron microscopy. ► The slight increases in T_c were observed for samples studied in this work in the range 275–285K.A series of Sr doped lanthanum manganites were synthesized by simple solution combustion technique and annealed at temperature 600°C. All LSMO samples were structurally and morphologically characterized by XRD and SEM, respectively. The nanocrystalline nature of LSMO was studied by TEM. The effect of Sr doping on magnetic properties was studied by vibrating sample magnetometer and SQUID magnetometer. The minor change in saturation magnetization observed but the coercivity decreases first and then increases with increase in Sr content. The Curie temperature ( T_c) increases from 275K to 285K for LSMO samples as x varies from 0.1 to 0.3.

Keywords: LSMO; Magnetic properties; Morphological properties; SQUID

Characteristics of microstructure and mechanical properties of Sc films as a function of substrate temperature by Qingying Wu; Jianhua Liang; Jinhua Liu; Wenzeng Bing; Xinggui Long; Shunzhong Luo (pp. 7421-7424).

► The effect of substrate temperature (100–650°C) on the Sc films is studied. ► Sc films at lower temperatures are oxidized easier than those at higher temperatures. ► Easier oxidation is attributed to the smaller grain size and lower diffusibility of oxygen in Sc film. ► Hardness and modulus are mainly influenced by the grain size and degree of oxidation.Scandium films were deposited on molybdenum (Mo) substrates, at different substrate temperatures (100–650°C) by electron-beam evaporation. The oxidation behavior was investigated by X-ray photoelectron spectroscopy (XPS). Hardness and elastic modulus of Sc films were measured by the nano-indentation technique. XPS depth profile results demonstrate that Sc films deposited at lower substrate temperatures are oxidized easier than those at higher temperatures. Besides the effect of thermodynamics, the easier oxidation at lower temperatures may be attributed to the smaller grain size and lower diffusibility of oxygen in the inner film. Increasing substrate temperature first decreases the hardness and elastic modulus due to the increased grain size and decreased degree of oxidation. Then, when the temperature increases from 450°C to 550°C, the hardness and elastic modulus are improved owing to the higher texture coefficient and densification, as well as the abnormally decreased grain size. However, when the temperature further increases to 650°C, the hardness and elastic modulus decrease again.

Keywords: Scandium film; Oxidation behavior; Hardness; Elastic modulus; Substrate temperature; Electron-beam evaporation

Theoretical study of Cs adsorption on GaN(0001) surface by Du Yujie; Chang Benkang; Wang Xiaohui; Zhang Junju; Li Biao; Wang Meishan (pp. 7425-7429).

► Using density functional theory with a plane-wave ultrasoft pseudopotential method based on first-principles calculations, we have found that the most stable positions of Cs adatoms on (2×2)GaN(0001) surface are at N-bridge and H3 sites for 1/4 monolayer coverage. ► The change of adsorption energies and the change of work function with coverage from 1/4 to 1 monolayer are analyzed, and the reason for those changes is also analyzed. ► These results provide a theoretical reference for the activation experiment of negative electron affinity GaN optoelectronic cathodes.The adsorption characteristics and change in work function of Cs on a (2×2) GaN(0001) surface with a coverage from 1/4 to 1 monolayer (ML) have been investigated using density functional theory with a plane-wave ultrasoft pseudopotential method based on first-principles calculations. The results show that the most stable positions of Cs adatoms on GaN(0001) surfaces are at N-bridge and H3 sites for 1/4 ML coverage. As the Cs atomic coverage is increased, adsorption energy and stability reduce and achieve saturation when the Cs adatom coverage is 3/4 ML. The transfer of Cs6s electrons to Ga atoms in the outermost layer decreases the work function of the system.

Keywords: PACS; 71.55.Eq; 78.20.CiFirst-principles; Cs/GaN(0; 0; 0; 1) adsorption system; Adsorption energy; Electronic structure; Work function

Simple and eco-friendly preparation of silver films coated on copper surface by replacement reaction by Jun Zhao; Dongming Zhang; Xingjuan Song (pp. 7430-7434).

► Cu–Ag core–shell bimetallic powders with high silver content were fabricated. ► The use of green citric acid and PVP in fabricating Cu–Ag composite bimetallic powders has never been reported detailedly. ► This fabrication system is simple, eco-friendly and high-efficiency.Copper powders were coated by columnar nanostructured silver films by replacement reaction in aqueous system with PVP and citric acid at room temperature. The dense and uniform silver coating layer was obtained by strictly controlling Ag/Cu ratio. With different Ag/Cu ratio, different content of Ag in the composite can be obtained. The mechanism of composite powders formation and their characteristics were discussed in detail. It is noted that citric acid and PVP play different roles in preparing high quality Cu–Ag composite powders.

Keywords: Cu; Ag; Coating; Core–shell; Antioxidation

Transparent conductive p-type lithium-doped nickel oxide thin films deposited by pulsed plasma deposition by Yanwei Huang; Qun Zhang; Junhua Xi; Zhenguo Ji (pp. 7435-7439).

► Transparent p-type Li_0.25Ni_0.75O conductive films were prepared by pulsed plasma deposition. ► The influences of substrate temperature and oxygen pressure on properties of films were investigated. ► The electrical and optical properties were discussed detailedly and explained possibly. ► The hetero-junction diode p-NiO:Li/n-SnO₂:W exhibits rectifying I– V characteristics.Transparent p-type Li_0.25Ni_0.75O conductive thin films were prepared on conventional glass substrates by pulsed plasma deposition. The effects of substrate temperature and oxygen pressure on structural, electrical and optical properties of the films were investigated. The electrical resistivity decreases initially and increases subsequently as the substrate temperature increases. As the oxygen pressure increases, the electrical resistivity decreases monotonically. The possible physical mechanism was discussed. And a hetero p–n junction of p-Li_0.25Ni_0.75O/n-SnO₂:W was fabricated by depositing n-SnO₂:W on top of the p-Li_0.25Ni_0.75O, which exhibits typical rectifying current–voltage characteristics.

Keywords: Transparent conductive oxide; p-Type; Lithium-doped nickel oxide; p–n Junction; Electrical and optical properties

Sintering temperature effect on photocatalytic efficiencies of ZnO/TiO₂ composite plates by Mehmet Konyar; H. Cengiz Yatmaz; Koray Öztürk (pp. 7440-7447).

Display Omitted► We prepared self-supporting ZnO–TiO₂ photocatalyst composite plates by tape casting. ► Relatively low sintering temperature range (600–700°C) was selected. ► Decreasing sintering temperature suppresses the formation of Zn₂TiO₄ and Zn₂Ti₃O₈. ► The plates have relatively high surface areas and are efficient in degradation. ► RR180 dye molecules in water were successfully decomposed under UVA irradiation.Self-supporting ZnO/TiO₂ composite plates were fabricated at a molar ratio of ZnO (wurtzite):TiO₂ (anatase)=1:1 by tape casting and lamination process. The laminated green plates were sintered in air at relatively low temperatures, ranging from 600 to 700°C and finally characterized by TGA, BET, XRD and SEM-EDX analysis. Photocatalytic efficiencies of the plates were evaluated using a model aqueous dye solution (50mg/L RR180). Decolorization effect of the photocatalyst plates was carried out in a laboratory scale quartz photo-reactor under UVA light irradiation. It was found that increasing sintering temperatures reduced the efficiencies of the plates. This is due not only to decrease in the surface area of the plates because of coarsening, but also to reactions between phase-pure ZnO and TiO₂ leading to the formation of unwanted binary Zn₂Ti₃O₈ and Zn₂TiO₄ compounds. Up to 76% color removal was successfully achieved for the plates sintered at 600°C at the end of 90min oxidation process.

Keywords: Photocatalysis; UVA; ZnO/TiO; ₂; composite plate; Tape casting

High-temperature hydrothermal synthesis of crystalline mesoporous TiO₂ with superior photo catalytic activities by Fujian Liu; Chun-Lin Liu; Baowei Hu; Wei-Ping Kong; Chen-Ze Qi (pp. 7448-7454).

Display Omitted► Crystalline mesoporous TiO₂ was successfully synthesized at high temperature. ► Novel complex bond interaction results in stable mesopores. ► High-temperature hydrothermal condition can enhance crystallization of TiO₂. ► Crystallized mesoporous TiO₂ were photo catalytically active in both oxidation and reduction.Mesoporous titanium dioxide with crystalline mesopore walls (M-TiO₂- ns) have been successfully synthesized through the self-assembly of poly 4-Vinylpyridine template and tetrabutyl titanate precursor based on their complex bond interaction under high temperature (180°C) hydrothermal conditions. X-ray diffraction shows that M-TiO₂- ns have highly crystalline mesopore walls with anatase phase characters; N₂ sorption–desorption isotherms, SEM and TEM images show that M-TiO₂- ns have high BET surface areas (85 and 120m²/g, respectively), large pore volumes (0.32 and 0.34cm³/g, respectively) and crystalline mesopore walls, which exhibit monolithic morphology with crystal sizes around 3–5μm. Interestingly, M-TiO₂- ns exhibit much higher catalytic activities and good recyclability in both induced reduction of decabromodiphenyl and oxidation of Rhodamine B under UV light than those of nonporous crystalline TiO₂ and M-TiO₂ templated by hydrocarbon surfactant of F127, which is even comparable with that of commercial P25. Combination of the unique characters such as crystallinity, stable mesostructure, large BET surface areas and superior photo catalytic activities make M-TiO₂- ns a kind of potentially important material for removing of organic pollutions in environment through green photo irradiation processes.

Keywords: High temperature synthesis; Crystalline mesoporous TiO; ₂; Complex bond interaction; Photo catalysis; Recyclability

Fabrication of superhydrophobic vanadium pentoxide nanowires surface by chemical modification by Karuppanan Senthil; Guenjae Kwak; Kijung Yong (pp. 7455-7459).

Schematic illustration showing the modification of a hydrophilic V₂O₅ NWs/Si surface into an OTS modified superhydrophobic V₂O₅ NWs/Si surface.Display Omitted► Vanadium pentoxide nanowires are synthesized by physical vapor deposition. ► The nanowires are single crystalline having orthorhombic V₂O₅ phase. ► Octadecyltrichlorosilane deposition changed the hydrophilic nanowire surface to hydrophobic surface. ► Superhydrophobicity are attributed to the high surface roughness and low surface energy.Vanadium pentoxide (V₂O₅) nanowires have been synthesized on Au-coated Si substrates by a physical vapor deposition process. The synthesized nanowires are randomly oriented with a diameter around 40–200nm and length of several micrometers. The crystalline structure of the nanowires analyzed by using X-ray diffraction and Raman spectroscopy corresponds to single crystalline orthorhombic V₂O₅ phase with [001] growth orientation. The transmission electron microscopy and energy-dispersive X-ray analysis suggests a possible vapor–solid (VS) growth mechanism for the V₂O₅ nanowires. A self-assembled monolayer (SAM) of octadecyltrichlorosilane (OTS) was deposited on the V₂O₅ nanowires to obtain superhydrophobic V₂O₅ nanowire surfaces with water contact angle (CA) of 157.5°. The superhydrophobic behavior is attributed to the high surface roughness provided by the nanowire surface and low surface energy due to SAM layer deposition. The impact dynamics of water droplets impinging on the superhydrophobic surface is also investigated.

Keywords: Oxides; Nanowire; Morphology; Surface energy; Superhydrophobicity

A corrosion-resistance superhydrophobic TiO₂ film by Yawei Hu; Siya Huang; Shan Liu; Wei Pan (pp. 7460-7464).

Display Omitted► TiO₂ suspension containing TiO₂ nanoparticles as precursors. ► TiO₂ nanoparticles leaded to the hierarchical structure. ► Superhydrophobic TiO₂ film with great high water contact angle of 173.7°. ► The film still showed superhydrophobicity after corroded with strong acid. ► The film prevented the metal substrate from corrosion.A superhydrophobic TiO₂ film with water contact angle greater than 170° on Hastelloy substrate was fabricated through simply dip-coating method from TiO₂ precursor solution containing TiO₂ nanoparticles with the average diameter 25nm, followed by heat-treatment and modification with fluoroalkylsilane (FAS) molecules. The as-obtained sample was characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and water contact angle measurement respectively. Moreover, the dynamic light scattering (DLS) size distribution of TiO₂ aggregated particles in the TiO₂ precursor solution containing P25 particles was evaluated by Laser Particle Sizer. It is found that the TiO₂ nanoparticles in TiO₂ precursor solution play a crucial role to form high superhydrophobicity. Simultaneously, the superhydrophobic TiO₂ film still showed great superhydrophobicity after corroded with strong acid or alkali solutions and protected the substrate from corrosion which should be critical to the potential application in industry.

Keywords: TiO; ₂; film; Superhydrophobicity; Corrosion-resistance

Effects of hydrothermal annealing on characteristics of CuInS₂ thin films by SILAR method by Yong Shi; Fanghong Xue; Chunyan Li; Qidong Zhao; Zhenping Qu; Xinyong Li (pp. 7465-7469).

► A new hydrothermal annealing method could be used to prepare CuInS₂ films grown on glass substrates by SILAR method. ► Single-phase chalcopyrite CuInS₂ films are obtained by hydrothermal annealing of SILAR-deposited films for different time in Na₂S solution. ► The annealed CuInS₂ films were well-crystallized and slightly S-rich.CuInS₂ thin films have been deposited by successive ionic layer absorption and reaction (SILAR) method, then annealed in a Na₂S solution (denoted as hydrothermal annealing) at 200°C for different time. The effect of hydrothermal annealing on the properties of the films was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and optical absorption spectroscopy. The XRD, TEM and SEM results indicate that well-crystallized CuInS₂ films could be obtained after annealing in 0.1mol/L Na₂S solution for 1.5h. The annealed CuInS₂ films were slightly S-rich and the direct band gap varied from 1.32 to 1.58eV as the annealing time increased from 0.5h to 2h.

Keywords: CuInS; ₂; Thin films; SILAR preparation; Hydrothermal annealing

Surface modification of Cameroonian magnetite rich clay with Eriochrome Black T. Application for adsorption of nickel in aqueous solution by Paul Djomgoue; Mermoz Siewe; Emmanuel Djoufac; Pascalin Kenfack; Daniel Njopwouo (pp. 7470-7479).

Display Omitted► The surface of a Cameroonian magnetite rich clay was modified using Eriochrome Black T, EBT. ► The immobilized surfaces were used for nickel (II) ion adsorption from aqueous solution. ► The characterization of the surface modification was also performed with IR and ZPC measurements. ► The EBT-functionalized magnetite rich clay presented a binding capacity of nickel (II) ion about 30% higher compared to the untreated sample.In this study, the surface of Cameroonian magnetite rich clay was modified using Eriochrome Black T, EBT by the batch adsorption method. The EBT-modified magnetite rich clays were used for nickel ions adsorption from aqueous solution. The effect of various experimental factors; the pH of solution, the influence of concentration, the temperature, the contact time and the particle size of the sample were studied by using the batch technique. Adsorption process was better described by the pseudo-second-order kinetic and Tempkin isotherm model. The results showed that the EBT adsorption onto samples is affected by the pH of solution and the maximum EBT ion adsorption takes place between pH 2 and pH 3. The characterization of the surface modification was performed with FTIR and ZPC measurements. The FTIR shows that chemisorption took place at the surface of the bulk samples. The EBT-modified magnetite rich clay presented a binding capacity of nickel ions about 30% higher compared to the unmodified samples from an initial nickel ions concentration of 5.26mmol using 0.5g of sample.

Keywords: Clay; Magnetite; Eriochrome Black T; Adsorption; Nickel (II)

Resistance to protein and oil fouling of sulfobetaine-grafted Poly(vinylidene Fluoride) hollow fiber membrane and the electrolyte-responsive behavior in NaCl solution by Qian Li; Qiu-Yan Bi; Tian-Yin Liu; Xiao-Lin Wang (pp. 7480-7489).

Display Omitted► Excellent protein-fouling-resistance of the sulfobetaine-grafted PVDF membrane was shown during filtration of BSA solution with NaCl. ► The potential of the modified PVDF membrane to resist the oil fouling was confirmed through filtration of oil-in-water emulsion with NaCl. ► The results extended the application of PVDF hollow fiber membrane in the fields of bio-separation, oil and wastewater treatment.An excellent protein-fouling-resistance performance of the sulfobetaine-grafted PVDF hollow fiber membrane was obtained and the potential of sulfobetaine-grafted PVDF membrane to resist the oil fouling was confirmed in the filtration solution which contained inorganic electrolyte, sodium chloride (NaCl). The electrolyte-responsive behavior of the sulfobetaine-modified PVDF membrane was demonstrated by the filtration of NaCl aqueous solution. The grafting amount of the modified PVDF hollow fiber membrane showed a stable value as 680μg/cm². An almost complete coverage of the membrane surface by the grafted sulfobetaine polymer contributed to the high hydrophilicity and membrane strength. The membrane surface became denser and the permeate flux reduced with the increase of NaCl concentration. The cyclic filtration experiment showed that during the filtration of the protein solution with 0.05mol/L of NaCl, the sulfobetaine-grafted PVDF membrane exhibited an excellent protein-fouling-resistance performance with a high relative flux recovery of 98.2% and a low irreversible fouling extent which was lower 10 times than that of the nascent PVDF hollow fiber membrane. In addition, the sulfobetaine-grafted PVDF hollow fiber membrane showed an oil-fouling-resistance property during the filtration experiment of the oil-in-water emulsion with 0.05mol/L of NaCl, resulting in an relative flux recovery of about twice that of the nascent PVDF membrane. The results extended the application of poly(sulfobetaine)-g-PVDF hollow fiber membrane in the fields of bio-separation, artificial oil and wastewater treatment.

Keywords: Protein-fouling-resistance; Oil-fouling-resistance; Inorganic electrolyte; Sulfobetaine polymer; Poly(vinylidene fluoride) hollow fiber membrane

Tribological behavior of cold-sprayed nanocrystalline and conventional copper coatings by Jingchun Liu; Xianglin Zhou; Xiong Zheng; Hua Cui; Jishan Zhang (pp. 7490-7496).

A bright-field TEM image (a) and a corresponding SAED pattern (b) of the cold sprayed nanocrystalline Cu coating. Three-dimensional reconstructions by white-light interferometry on the NC Cu coating under the load of 10N (c), and the CG Cu coating under the load of 10N (d).Display Omitted► Nanocrystalline Cu coatings were successfully obtained on A6061 substrate via cold spraying. ► The microstructure and tribological properties were investigated. ► The enhancement of the wear properties of the NC Cu was attributed to the grain refinement and the superior hardness.Both the cryomilled Cu powder and the gas-atomized Cu powder were sprayed onto aluminum substrate using the cold spray process. This study focused on the formation and tribological behavior of the nanocrystalline (NC) Cu coating in comparison to its coarse-grained (CG) Cu counterpart. The results showed that the as-sprayed deposit presented a dense microstructure. The mean grain size of the NC Cu coating was about 30nm. Investigations on the worn surface of the NC coating revealed that the plastic deformation with grooves and some debris were prominent with no visible cracking. Nanocrystalline Cu coating showed a good wear resistance with a low friction coefficient. The enhancement of the wear properties of the NC Cu was attributed to the grain refinement and the superior hardness.

Keywords: Coating; Cold spray; Wear property; Microstruture

Electrochemical degradation of electrodeposited Pt particles on mask scratched substrate using a landmark for ex situ scanning electron microscopy by Akira Kishi; Mitsuhiro Inoue; Sayoko Shironita; Minoru Umeda (pp. 7497-7502).

► A mask scratched substrate with a landmark allows an ex situ SEM at the same point. ► The Pt particles are degraded by potential cycling at 100mmoldm⁻³ H₂O₂. ► The Pt particle degradations depend on the potential cycling range. ► The dissolved Pt is re-deposited during the potential cycling in 0.01–0.4V vs. RHE. ► The deposition of the dissolved Pt affects the change in the Pt particle degradations.Pt particles were deposited on a glassy carbon substrate using a landmark by a mask scratch-based Pt electrodeposition method to observe the same Pt particles by ex situ scanning electron microscopy before and after a potential cycling procedure. The potential cycling was conducted in a H₂O₂-containing 0.5moldm⁻³ H₂SO₄ solution. As a result, the Pt particle degradations are clearly observed in the solution containing 100mmoldm⁻³ H₂O₂ in the potential range of 0.04–1.44V vs. RHE; whereas, the degradations become more remarkable at 0.34–1.44V vs. RHE. To clarify the reason for this potential cycling range-dependence of the Pt particle degradations, the weight change of a Pt electrode during potential cycling in the presence of H₂O₂ was measured using an electrochemical quartz crystal microbalance. The result suggests that the dissolved Pt is re-deposited on the Pt in ca. 0.01–0.40V vs. RHE, which well explains the difference of the Pt particle degradations by the potential cyclings between 0.04–1.44 and 0.34–1.44V vs. RHE.

Keywords: Pt particle; Potential cycling; AFM mask scratch; Landmark; Pt electrodeposition; Ex situ SEM observation

Precipitation of gold nanoparticles on insulating surfaces for metallic ultra-thin film electroless deposition assistance by P. Livshits; A. Inberg; Y. Shacham-Diamand; D. Malka; Y. Fleger; Z. Zalevsky (pp. 7503-7506).

Display Omitted► The kinetics of 15 and 25nm AuNPs precipitation on SAM/SiO₂/Si surface were studied. ► 15nm NPs are promising candidate to catalyze the deposition of ultra-thin films. ► NPs independently of their size precipitate with a certain regularity and order. ► NPs are organized in pairs and under certain angle. ► In each pair NPs are located at 50–60nm from each other.In this work, the kinetics of 15 and 25nm gold nanoparticle (AuNP) precipitation on silanized SiO₂/Si surfaces were studied. The NP coverage as well as distribution on the substrates was explored. It was found that at the beginning of the process, the 25nm AuNPs precipitate faster than their 15nm counterparts. However, early saturation and low final surface coverage by these NPs were observed. The 15nm AuNPs, exhibited higher (∼40%) surface coverage and precipitation saturation only after longer treatment times. This makes small NPs a promising candidate for catalyzing the deposition of ultra-thin metallic films on insulating substrates. In addition, it has been demonstrated for the first time that NPs, independently of their size, precipitate with a certain regularity and order. Using high-resolution scanning electron microscopy (HRSEM) it was observed that NPs are organized in pairs, and in each pair they are located at 50–60nm from each other and under certain angle.

Keywords: Precipitation of gold nanoparticles; SiO; ₂; /Si surfaces; Ultra-thin films; Electroless deposition

Effect of surface oxide on the melting behavior of lead-free solder nanowires and nanorods by Fan Gao; Karunaharan Rajathurai; Qingzhou Cui; Guangwen Zhou; Irene NkengforAcha; Zhiyong Gu (pp. 7507-7514).

Display Omitted► Surface oxide of nanosolders plays a critical role in the melting of solder nanowires and nanorods. ► Flux can effectively remove the surface oxide layer and ensure complete nanosolder reflow. ► An interesting Ostwald ripening phenomenon was observed during the melting of solder nanowires and nanorods, which led to the formation of nano- and micro-sized solder balls. ► The smallest solder balls that we have observed are in the range of tens of nanometer. ► A significant shape change (quasi-melting) was observed for these nano-solders at a temperature well below the apparent melting point temperature, which underlines the importance of the solder reflow conditions.Lead-free nanosolders have shown promise in nanowire and nanoelectronics assembly. Among various important parameters, melting is the most fundamental property affecting the assembly process. Here we report that the melting behavior of tin and tin/silver nanowires and nanorods can be significantly affected by the surface oxide of nanosolders. By controlling the nanosolder reflow atmosphere using a flux, the surface oxide of the nanowires/nanorods can be effectively removed and complete nanosolder melting can be achieved. The complete melting of the nanosolders leads to the formation of nanoscale to microscale spherical solder balls, followed by Ostwald ripening phenomenon. The contact angle of the microscale solder balls formed on Si substrate was measured by direct electron microscopic imaging. These results provide new insights into micro- and nanoscale phase transition and liquid droplet coalescence from nanowires/nanorods to spheroids, and are relevant to nanoscale assembly and smaller ball grid array formation.

Keywords: Nanosolder; Nanowires; Surface oxide; Melting; Flux; Nanoelectronics assembly

Fabrication of ZnO nanoparticles based sensitive methanol sensor and efficient photocatalyst by M. Faisal; Sher Bahadar Khan; Mohammed M. Rahman; Aslam Jamal; M.M. Abdullah (pp. 7515-7522).

.Display Omitted► Newly synthesis of ZnO nanoparticles at low temperature by hydrothermal method. ► First report on methanol sensing using ZnO nanoparticles utilizing reliable I– V technique. ► Highly efficient photocatalyst for the removal of organic pollutants.ZnO nanoparticles (NPs) were prepared by hydrothermal treatment with starting materials (zinc chloride and urea) in the presence of ammonium hydroxide and characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and UV–vis spectroscopy. The synthesized nanoparticles are crystalline with wurtzite hexagonal phase having average particle size in the range of 80–130nm. Photocatalytic activity of the prepared ZnO NPs was evaluated by the degradation of methylene blue and almost complete degradation (91.0%) takes place within 85min of irradiation time. Prepared ZnO nanostructures possessed high photocatalytic activity when compared with TiO₂-UV100. Additionally, the sensing properties of the ZnO films were investigated for various concentrations of methanol in liquid phase by simple I– V technique at room conditions. It was observed that ZnO thin film exhibits good sensitivity (0.9554μAcm⁻²mM⁻¹) towards detection of methanol at room conditions.

Keywords: ZnO nanoparticles; Hydrothermal synthesis; Methanol chemical sensor; Photocatalyst; Methylene Blue

SBA-15 mesoporous material modified with APTES as the carrier for 2-(3-benzoylphenyl)propionic acid by Michał Moritz; Marek Łaniecki (pp. 7523-7529).

N₂ adsorption–desorption isotherms of pure SBA-15, aminopropyl-modified SBA-15 and the carrier after drug adsorption.Display Omitted► Modification of SBA-15 internal channels with–NH2 groups. ► Adsorption of ketoprofen on modified SBA-15. ► Release of supported ketoprofen from modified SBA-15.SBA-15 ordered mesoporous silica functionalized with (3-aminopropyl)triethoxysilane (APTES) was used as the carrier for anti-inflammatory drug: 2-(3-benzoylphenyl)propionic acid – ketoprofen. The surface of SBA-15 containing free silanol groups was modified with 3-aminopropyltriethoxysilane via post-synthetic reaction. Functionalization of the carrier with basic aminopropyl groups resulted in an ionic interaction with acidic ketoprofen. The samples of carriers and carrier-drug complexes were characterized by elemental analysis, TG, N₂ adsorption, FTIR, DRUV spectroscopies and an in vitro drug release test. The adsorption of ketoprofen on modified mesoporous matrix was proportional to the amount of introduced aminopropyl groups. The maximum content of deposited drug in modified SBA-15 was close to 20wt.%. After drug adsorption the reduction of BET surface area, pore volume and pore diameter of non-modified SBA-15 and aminopropyl-modified SBA-15 after drug adsorption were observed while the hexagonal array of siliceous matrix was well preserved. The release profiles of the aminopropyl-modified drug-containing SBA-15 exhibited prolonged release of ketoprofen in applied media. Tests performed in acidic solution (pH 1.2) showed the best pharmaceutical availability.

Keywords: SBA-15; APTES; Ketoprofen adsorption; Drug release

Segmented magnetic nanofibers for single cell manipulation by Jun Liu; Jian Shi; Lianmei Jiang; Fan Zhang; Li Wang; Shinpei Yamamoto; Mikio Takano; Mengjie Chang; Haoli Zhang; Yong Chen (pp. 7530-7535).

Display Omitted► Electrospun magnetic nanofibers were uniformly segmented using a sonication technique. ► The produced fiber segments showed a quick mechanic response under external magnetic field. ► They could also be used for single and collective cell manipulation with external magnetic field.We report a simple but straightforward approach to fabricate magnetic nanofiber segments for cell manipulation. Electrospinning was used to produce nanofibers from a magnetic nanoparticles containing polymethylglutarimide (PMGI) precursor solution. After sonication, the fabricated nanofibers were uniformly segmented. When dispersed in an aqueous solution, the orientation of the fiber segments could easily be controlled by an external magnetic field. NIH 3T3 cells were then cultured in a medium containing magnetic fibers, resulting in stable cell-nanofiber hybrids which can be conveniently manipulated with a magnet.

Keywords: Nanofibers; Cell culture; Magnetic manipulation

Decoration of CdS nanoparticles on MWCNT's by simple solution chemistry by Prashant Baviskar; Padmakar Chavan; Namdev Kalyankar; Babasaheb Sankapal (pp. 7536-7539).

Simple and inexpensive solution chemistry is applied for decoration/formation CdS nanoparticles on MWCNT's. Simple ion-by-ion mechanism is utilized for the deposition of CdS nanoparticles on MWCNTs ▪.► The decoration of CdS nanoparticles over MWCNTs was done at low temperature (70°C). ► Simple and inexpensive route namely chemical bath deposition method was employed. ► The CdS nanoparticles coated on MWCNTs clearly demonstrates size quantization. ► The process opens way to coat variety of inorganic semiconducting nanoparticles.Simple and inexpensive solution chemistry is applied for decoration/formation CdS nanoparticles on multiwall carbon nanotubes (MWCNT's). Simple ion-by-ion mechanism is utilized for the deposition of CdS nanoparticles on MWCNT's. The size of the nanoparticles is controlled by tuning the preparative parameters which is most favorably based on ion-by-ion mechanism. The use of alkaline medium is completely avoided. Complete decoration of CdS nanoparticles on MWCNT's with cubic structure is observed by structural and surface morphological studies. The photoluminescence spectroscopy shows the two intense luminescence bands, i.e. blue and green, evidencing the presence of small size and agglomerated big size particles of CdS over MWCNT's (size-effect). The modification of MWCNT's with CdS presented in this study opens up new avenues in the design of optoelectronic and light-energy conversion devices.

Keywords: MWCNT's; CdS nanoparticles; Chemical synthesis; Low temperature; Nanocomposite

The surface organic modification of tourmaline powder by span-60 and its composite by Yingmo Hu; Xue Yang (pp. 7540-7545).

IR spectra of tourmaline (a), modified tourmaline (b) and span 60 (c)Display Omitted► Factors that influence the modification effects were investigated. ► The modified tourmaline was characterized with IR, XRD, SEM and TGA curves. ► The amount of negative ions released of modified tourmaline is more than 2.4 times. ► The dispersancy of modified tourmaline in PP is much better. ► The amount of negative ions released of the modified tourmaline/PP is much more.To improve the compatibility and dispersed stability between tourmaline and a polymer resin matrix, the surface organic modification of tourmaline powder with span-60 was studied, and factors that influence the modification effects were investigated using the activation index and contact angle. The results showed that the activation index of modified tourmaline powder approached 100% after tourmaline powder was reacted with 3% (of tourmaline mass) span-60 at 60°C in toluene for 1h. Structural analysis revealed that hydrophobic alkyl groups attached to the surface of tourmaline due to the reaction of span-60 with hydroxyl groups attached to the surface of tourmaline due to the reaction of span-60 with hydroxyl groups. The attachment of the alkyl groups improved the hydrophobic surface properties of tourmaline without altering its crystal configuration. The amount of negative ions released from modified tourmaline was greater than that released from unmodified tourmaline. The dispersancy of modified tourmaline in polypropylene was clearly better than that of unmodified tourmaline, and the amount of negative ions released from the modified tourmaline/PP composite was greater than that released from the unmodified tourmaline/PP composite.

Keywords: Tourmaline; Surface treatments; Span-60; Activation index; Negative ion; Functional composites

Investigation of the bonding of SiH_n and CH_n ( n=1,…,3) on Cu(111) using DFT by I.G. Shuttleworth (pp. 7546-7551).

.Display Omitted► The HCP binding site of SiH_n/Cu(111) is due to the removal of unoccupied Si 3p–Cu 4s anti-bonding states by second layer Cu. ► A similar interaction is shown to drive CH_n fragments to the experimentally-preferred three-fold sites. ► A simplistic approach to identifying site preference/reactive center is presented based on the COOP and PDOS of the system.The interaction of SiH_n and CH_n ( n=1,…,3) fragments with the three-fold sites of Cu(111) has been investigated using LCAO-DFT. The binding site preference for the HCP site (SiH_n) has been shown to be due to the removal of unoccupied Si 3p–Cu 4s anti-bonding states by the second layer Cu ion cores. A similar but less pronounced effect is shown between the C 2p–Cu 4s interaction for CH_n fragments bound in the FCC site.

Keywords: CH; _n; SiH; _n; Methyl; Silyl; Binding energy; FCC; HCP; Three-fold; Cu(1; 1; 1); LCAO; DFT; BSSE

Controllable fabrication of organosilane nano-architectured surfaces with tunable wettability by Meihua Jin; Shasha Li; Jing Wang; Mingyi Liao; Yong Zhao (pp. 7552-7555).

Nano-architectured trichlorosilane-derived surfaces are controllable fabricated by a simple phase separation reaction. It shows tunable surface nano-architecture with the growth of alkyl chain length, as well as the corresponding wettability. The competition between the steric effect and hydrophobicity of alkyl chain is considered to be responsible for the behavior.Display Omitted► The organosilane nano-architectured surfaces were controllable fabricated on glass substrates by liquid phase method. ► The surfaces prepared by through hydrolysis and polycondensation of trichlorosilanes in toluene solution with trace water. ► The alkyl length of trichlorosilanes was found to have critical influence on the surface nano-architectures and corresponding wettability. ► These behaviors originate from the competition between steric effect and alkyl hydrophobicity.Trichlorosilanes nanostructures have been fabricated on glass substrates through a fast and facile liquid phase method and the impact of alkyl length on surface nanostructures and the corresponding wettability have been studied. With the increase of alkyl chain length, the prepared surfaces showed different surface geometries on shape, size and quantity, as well as the corresponding wettability. The competition between the decrease of the reactivity caused by the raise of the steric effect and the increase of the alkyl hydrophobicity with the variation of alkyl length is considered to be responsible for these behaviors.

Keywords: Nano-architectures; Tunable wettability; Organosilane; Liquid phase method

Enhanced microwave absorption of BaTiO₃-based ferroelectric/ferromagnetic nanocomposite by Zhi Ma; Chentao Cao; Jing Yuan; Qingfang Liu; Jianbo Wang (pp. 7556-7561).

► NiCoP/BaTiO₃ and carbonyl iron/BaTiO₃ nanocomposite are prepared by electroless plating and mechanical milling method, respectively. ► The increasing in coercivity after mechanical alloying is due to the residual stress, impurities and defects. ► We also find that resonance of permittivity should arise from dipole polarization, magnetic loss should arise from natural resonance and exchange resonance. ► It is evident that NiCoP/BaTiO₃ composite is a narrowband microwave absorber, and carbonyl iron/BaTiO₃ composite shows broadband absorption characteristics.Morphology, crystal structure, magnetic and microwave absorption properties of BaTiO₃-based ferromagnetic/ferroelectric composites were investigated in this research. It was evident that NiCoP/BaTiO₃ composite was a narrowband absorber, whereas carbonyl iron/BaTiO₃ composite samples showed broadband absorption characteristics. For the carbonyl iron/BaTiO₃ composite, a reflection loss exceeding −20dB was obtained in the frequency range of 3.8–5.8GHz with an absorber thickness of 2.3–3.3mm. An optimal RL of −46dB was found at 4.7GHz for an absorber thickness of 2.8mm. The effective absorption bandwidth with RL<−10dB was extended and reached 16GHz (2–18GHz). Moreover, the intrinsic reasons for microwave absorption of the composites, the dielectric loss and magnetic loss mechanics were also investigated.

Keywords: Nanoparticles; Polarization; Microwave absorption

Preparation of ultrathin polydimethylsiloxane-coating on Cu as oxidation-protection layer by Yoon-Hyun Kim; Myung-Geun Jeong; Hyun Ook Seo; Seong-Yong Park; In-Bum Jeong; Kwang-Dae Kim; Sung Min Cho; Dong Chan Lim; Young Dok Kim (pp. 7562-7566).

► Polydimethylsiloxane (PDMS) thin films on Cu particles were fabricated. ► X-ray photoelectron spectroscopy and FT-IR was used for characterization of the thin films. ► PDMS coating can protect Cu surface from oxidation.Very thin polydimethylsiloxane (PDMS)-layer with a mean thickness of 3–5nm was formed on Cu particles by using thermal evaporation of PDMS at 200°C under nitrogen atmosphere. Using X-ray photoelectron spectroscopy and FT-IR, it was shown that the dimethylsiloxane framework was sustained after evaporation of PDMS and its deposition on Cu particles. Initiation temperature for oxidation of Cu was shifted to a higher temperature by more than 50°C in the presence of PDMS-layer, indicating that PDMS can be used as protection layer of metal particles in various applications.

Keywords: Oxidation; Metal; Protection; PDMS

Modification of the properties of polythiophene thin films by vapor chopping by Sandip V. Kamat; J.B. Yadav; Vijaya Puri; R.K. Puri (pp. 7567-7573).

Display Omitted► Vapor chopping produces cross-linking of polymers, causes the shifting in the vibration bands in FTIR and binding energy. ► Vapor chopping gives uniform and smooth surface morphology with fewer defects. ► Vapor chopping reduces the band gap and refractive index of the thin film. ► The contact angle reduces due to vapor chopping.Polythiophene thin films (thickness∼250nm) were prepared on the glass substrates, these thin films were characterized for structural, surface morphological and optical properties. The effect of the vapor chopping on the properties of these thin films was studied. The shifting of vibration bands was observed in FTIR due to vapor chopping. A slight shift in the binding energy was also observed due to vapor chopping. Vapor chopped thin film shows more smoother surface morphology with reduced grain size (∼30nm) as compared to nonchopped films (∼45–50nm). The optical absorbance, band gap and refractive index decreased due to vapor chopping. The vapor chopping also reduces the water contact angle turning the films to hydrophilic.

Keywords: Polymer; Thin films; Vapor deposition; Infrared spectroscopy; Optical properties

Surface-nitriding treatment of steels using microwave-induced nitrogen plasma at atmospheric pressure by Shigeo Sato; Yuuki Arai; Noboru Yamashita; Atsushi Kojyo; Kenji Kodama; Naofumi Ohtsu; Yukio Okamoto; Kazuaki Wagatsuma (pp. 7574-7580).

► Nitrided layers several micrometers thick were formed within 1min. ► Nitrided layers on iron plates have a high nitrogen concentration near the solubility limit. ► The surface of high-chromium steels can be nitrided by introducing reducing gases.A rapid surface-nitriding system using microwave-induced nitrogen plasma at atmospheric pressure was developed for modifying iron and steel surfaces. Since the conventional plasma nitriding technique requires a low-pressure atmosphere in the treatment chamber, the population of excited nitrogen molecules in the plasma is limited. Accordingly, several hours are required for nitriding treatment. By contrast, the developed nitriding system can use atmospheric-pressure plasma through application of the Okamoto cavity for excitation of nitrogen plasma. The high population of excited nitrogen molecules induced by the atmospheric-pressure plasma allowed the formation of a nitriding layer that was several micrometers thick within 1min and produced an expanded austenite iron phase with a high nitrogen concentration close to the solubility limit on the iron substrate. In addition, the nitriding treatment on high-chromium steel was performed by introducing a reducing gas such as NH₃ and H₂ into the treatment chamber. While the nitriding reaction did not proceed in a simple N₂ atmosphere due to surface oxidation, the surface reduction induced by the NH₃ or H₂ gas promoted the nitriding reaction at the surface. These nitriding phenomena characteristics of the atmospheric-pressure plasma are discussed in this paper based on the effects of the specimen temperature and plasma atmosphere on the thickness, the chemical states, and the nitride compounds of the nitrided layer as investigated by X-ray diffraction, glow-discharge optical emission spectroscopy, and X-ray photoelectron spectroscopy.

Keywords: Surface nitriding; Plasma nitriding; Microwave-induced nitrogen atmospheric pressure plasma; X-ray photoelectron spectroscopy; Glow discharge optical emission spectroscopy; Depth profile

Structural, optical, and electrical properties of Cu₂O nanocubes grown on indium-tin-oxide-coated glass substrates by using seed-layer-free electrochemical deposition method by Young Soo No; Do Hyon Oh; Su Yeon Kim; Keon-Ho Yoo; Tae Whan Kim (pp. 7581-7583).

► P-type Cu₂O nanocubes were formed on indium-tin-oxide (ITO)-coated glass substrates without catalysts by using electrochemical deposition method. ► X-ray diffraction pattern showed that the nanocubes are in cubic phase, and photoluminescence spectra showed a dominant green band edge emission appearing at around 500nm. ► The ECD growth method had excellent advantages of simple, low cost, templateless, and mass production. ► The current–voltage characteristics for the Au/n-Al-doped ZnO (AZO)/p-Cu₂O nanocube/ITO diodes showed current rectifying behavior with a turn-on voltage of 3.6V. ► These results indicate that n-AZO/p-Cu₂O nanocube diodes hold promise for potential applications in next-generation optoelectronic devices.Electrochemical deposition was employed to fabricate Cu₂O nanocubes on indium-tin-oxide (ITO)-coated glass substrates at 75°C without using any template, catalyst, or seed layer. Scanning electron microscopy images showed that the Cu₂O nanocubes with a nanoscale size were uniformly formed on ITO-coated glass substrates. X-ray patterns of the Cu₂O nanocubes exhibited the dominant peaks corresponding to the Cu₂O cubic structures. The current–voltage curves of an Au/n-type Al-doped ZnO/p-type Cu₂O nanocube/ITO device clearly showed current rectifying behavior with a turn-on voltage of 3.6V.

Keywords: Cu; ₂; O nanocubes; Structural properties; Electrical properties

Preparation of bioactive TiO film on porous titanium by micro-arc oxidation by Xingping Fan; Bo Feng; Yuli Di; Xiong Lu; Ke Duan; Jianxin Wang; Jie Weng (pp. 7584-7588).

► TiO layer with high bioactivity were prepared on the porous titanium by micro-arc oxidation (MAO). ► The MAO time and applied voltage play an important role in the formation of phase of TiO crystal. ► The increases of MAO time and voltages have contributed to apatite formation apatite. ► The TiO layer prepared by MAO can be used to modify the surface of the porous titanium implants.In the present work, porous titanium with a porosity of 70% was prepared using the space-holder sintering process. Then the porous titanium was treated by micro-arc oxidation (MAO) in the aqueous electrolyte. The results showed that TiO layers were formed on titanium at applied voltages (90–100V) and in short time (1–3min). The morphology of the TiO layer was investigated and the apatite-inducing ability was evaluated in a modified simulated body fluid (2SBF). It revealed that the increases of MAO time and applied voltage contributed to the formation of bioactive apatite on the surface of film on the porous titanium scaffold. The TiO layer possesses high apatite-forming ability. Therefore, the TiO layer prepared by MAO can be used to modify the surface of the porous titanium implants.

Keywords: Porous materials; Titanium; Micro-arc oxidation; Titanium oxide (TiO); Bioactivity

Fabrication and properties of porous scaffold of magnesium phosphate/polycaprolactone biocomposite for bone tissue engineering by Fan Wu; Changsheng Liu; Brian O’Neill; Jie Wei; Yung Ngothai (pp. 7589-7595).

► Scaffolds made of magnesium phosphate (MP)/PCL biocomposite were developed for bone tissue engineering applications. ► The composite scaffold exhibits an interconnected porous structure with porosity around 73%. ► Hydrophilicity of the scaffolds was enhanced by the incorporation of MP component. ► The degradation rate of the scaffolds could be tuned by adjusting the content of MP component in the composite.In this study, porous scaffolds made of magnesium phosphate (MP)/polycaprolactone (PCL) biocomposite were developed for bone tissue engineering applications. The composite scaffolds were fabricated by the particulate leaching method using sodium chloride particles as porogen. The obtained scaffold with porosity around 73% presents a porous structure with interconnected open pores. Hydrophilicity of the scaffolds was enhanced by the incorporation of MP component as demonstrated by the water contact angle measurement. The results of the in vitro degradation study show that the MP/PCL composite scaffolds degraded faster than PCL scaffolds in phosphate buffered saline (PBS). In addition, the degradation rate of the scaffolds could be tuned by adjusting the content of MP component in the composite. The results indicate that the MP/PCL composite scaffold has a potential application in bone tissue engineering.

Keywords: PCL; Magnesium phosphate; Porous scaffold; Degradation

Wetting induced fluid spread on structured surfaces at micro scale by Ming Zhou; Juan Yu; Jian Li; Bo Wu; Wei Zhang (pp. 7596-7600).

► We investigate experimentally how the surface properties such as structure profiles and wetting properties play a role in driving fluid spread. ► These results indicate that the structured hydrophilic surfaces can offer certain drag force for fluid over them. ► Such drag force may provide an effective approach for fluid flow in microfluidic devices.Downsizing fluidic devices raises many problems, one been the rapid increase of pressure gradient that drives the fluid flow. In this context, the surface induced fluid spread has attracted increasing interest. Here, we experimental investigate how the surface properties such as structure profiles and wetting properties play their role in driving fluid spread. The structured surfaces with different structure profiles were fabricated by using nanosecond laser with line scanning mode on the Si substrates (typical hydrophilic material) and their wetting properties were adjusted by sputter-coating different material films with low surface energy. Then the spread of the red ink solution on the as-prepared surfaces was observed by a microscopy. We found that in all cases with different structure profiles and wetting properties, the red ink solution spreads along the grooves on the structured surfaces. The relation of the spreading distance of the red ink solution in these grooves ( z) with the spreading time t is in accord with the typical relation z= ct^1/2. With the increase in both the width of the grooves and the wetting properties, the parameter c increases, indicating that the red ink solution spreads in the grooves with a higher velocity. These results indicate that the structured hydrophilic surfaces can offer certain drag force for fluid over them. Such drag force may provide an effective approach for fluid flow in microfluidic devices.

Keywords: Nanosecond laser; Line scanning mode; Spreading distance; Film coating

Ultrashort pulse laser patterning of indium tin oxide thin films on glass by uniform diffractive beam patterns by Zheng Kuang; Walter Perrie; Dun Liu; Paul Fitzsimons; Stuart P. Edwardson; Eamonn Fearon; Geoff Dearden; Ken G. Watkins (pp. 7601-7606).

► We demonstrated ultrashort pulse laser parallel processing of ITO thin film using up to 25 diffractive beams. ► The diffractive multiple beams generated by a spatial light modulator had high uniformity (the energy variation <9%) by avoiding symmetrical geometry design. ► By synchronizing a scanning galvanometer, the processing demonstrated high flexibility to generate various surface patterns.In the last decade, indium tin oxide (ITO) has been most commonly employed to create transparent conducting oxides (TCOs) thin films for many industrial applications. It is usually necessary to pattern ITO thin films to create functional structures for specific applications. Direct-write micro-patterning of ITO thin films by ultra-short pulse lasers has demonstrated high quality without requiring multiple processing stations, compared with conventional patterning technologies (e.g. wet-etch lithography). However, the processing efficiency and throughput with a single beam can be insufficient because of the high level of attenuation needed for the output to meet the required ‘thermal-free’ parameters. In this paper, high throughput surface direct micro-structuring of ITO on glass is demonstrated by parallel processing using diffractive multiple ultrashort pulse laser beams ( λ=1064nm, τp=10ps). By avoiding periodic and symmetrical geometry design, the diffractive multiple beam pattern generated by a spatial light modulator has high uniformity (the energy variation between each diffractive beam is <9%). The ITO thin film is removed by laser ablation of 25 identical beams at the same time without any damage to the glass substrate. Additionally, by synchronizing a scanning galvanometer, the processing demonstrates high flexibility to generate various surface patterns.

Keywords: PACS; 42.40.Jv; 42.62.Cf; 81.20.WkUltrashort pulse laser; Spatial light modulator (SLM); Indium tin oxide (ITO)

Preparation of thin Ga-doped ZnO layers for core–shell GaP/ZnO nanowires by J. Novák; I. Novotný; J. Kováč; P. Eliáš; S. Hasenöhrl; Z. Križanová; I. Vávra; R. Stoklas (pp. 7607-7611).

► Core–shell nanowires were prepared by combination of RF sputtering and MOVPE growth. ► PN junction was created between n-type ZnO and p-type GaP material. ► Focused ion beam was used for preparation of ohmic contacts to ZnO/GaP nanowires.We studied the formation of a thin ZnO shell deposited by RF sputtering on GaP nanowires, which were grown on GaP(111)B substrates under vapour–liquid–solid mode by MOVPE. The ZnO layers had the nominal thickness between 10 and 120nm (measured on planar GaP substrate). The SEM and TEM characterization showed that the ZnO shells fully covered the surface of the NWs from top to bottom. Moreover, a PN junction was created between the nanocrystalline wurtzite ZnO shell and the zinc-blende GaP NW core. The (n)ZnO/(p)GaP PN junction was characterized by I– V characteristics and spectral response measurement. The spectral response showed that the photocurrent was generated mostly the ZnO shell layer and marginally in the GaP material.

Keywords: Core–shell nanowires; RF sputtering; Nanostructure

Synthesis of nano-sized lithium cobalt oxide via a sol–gel method by Guangfen Li; Jing Zhang (pp. 7612-7616).

► A novel sol–gel method coupling with a spin-coating process was used. ► Effects of molar ratio of Li:Co and the proportion of total metallic ion density:PAA density on the formation of nano-sized LiCoO₂ on silicon substrate were studied. ► Optimized calcination temperature facilitates a dense film with uniform particles and prevents porous structures formed on the substrate surface. ► Multiple-layers favor the formation of the homogeneous films with nano-sized particulars.In this study, nano-structured LiCoO₂ thin film were synthesized by coupling a sol–gel process with a spin-coating method using polyacrylic acid (PAA) as chelating agent. The optimized conditions for obtaining a better gel formulation and subsequent homogenous dense film were investigated by varying the calcination temperature, the molar mass of PAA, and the precursor's molar ratios of PAA, lithium, and cobalt ions. The gel films on the silicon substrate surfaces were deposited by multi-step spin-coating process for either increasing the density of the gel film or adjusting the quantity of PAA in the film. The gel film was calcined by an optimized two-step heating procedure in order to obtain regular nano-structured LiCoO₂ materials. Both atomic force microscopy (AFM) and scanning electron microscopy (SEM) were utilized to analyze the crystalline and the morphology of the films, respectively.

Keywords: Spin-coating; LiCoO; ₂; Polyacrylic acid; Thin film

Preparation and surface characterization of CuO and Fe₂O₃ catalyst by Samia A. Kosa; Islam Hamdy Abd El Maksod; Lateefa Alkhateeb; Eman Z. Hegazy (pp. 7617-7624).

Display Omitted► CuO and Fe₂O₃ supported on Egyptian Kaolin exhibit a catalytic activity. ► For hydroxylation of benzene to phenol ranges between 83% and 98%. ► CuO catalyst has a higher catalytic activity than that of Fe₂O₃ catalysts. ► The method of preparation varies the distribution between surface and bulk active sites. ► Thus, in impregnation method playing a significant role in the catalytic activity.Aromatic hydroxylation, using novel effective catalysts was developed by loading CuO and Fe₂O₃ nanoparticles onto Egyptian kaolin.The H₂O₂ was used as a green and environmentally benign oxidizing agent. The resulting catalysts were subjected to several characterization methods, including XRD, SEM, and EDX analysis. Next, the catalytic activity of these species in effecting the hydroxylation of benzene was evaluated.The compounds were loaded using two methods: impregnation and precipitation deposition. A detailed comparison between the two methods has been undertaken. EDX analysis enables us to differentiate between two types of active sites – surface and bulk active sites.

Keywords: Heterogeneous catalysis; Hydroxylation reactions; Kaolin; XRD; SEM; EDX; Surface characterizations

Selective appearance of several laser-induced periodic surface structure patterns on a metal surface using structural colors produced by femtosecond laser pulses by Jianwu Yao; Chengyun Zhang; Haiying Liu; Qiaofeng Dai; Lijun Wu; Sheng Lan; Achanta Venu Gopal; Vyacheslav A. Trofimov; Tatiana M. Lysak (pp. 7625-7632).

► Deep and uniform ripples can be induced on stainless steel surface by scanning femtosecond laser with an optimized energy density and scanning speed. ► Vivid structural colors that span the entire visible spectrum were observed when illuminating the surface with white light. ► Different patterns without spatial overlapping or with spatial overlapping can be selectively displayed with structural color.Ripples with a subwavelength period were induced on the surface of a stainless steel (301 L) foil by femtosecond laser pulses. By optimizing the irradiation fluence of the laser pulses and the scanning speed of the laser beam, ripples with large amplitude (∼150nm) and uniform period could be obtained, rendering vivid structural colors when illuminating the surface with white light. It indicates that these ripples act as a surface grating that diffracts light efficiently. The strong dependence of the ripple orientation on the polarization of laser light offers us the opportunity of decorating different regions of the surface with different types of ripples. As a result, different patterns can be selectively displayed with structural color when white light is irradiated on the surface from different directions. More interestingly, we demonstrated the possibility of decorating the same region with two or more types of ripples with different orientations. In this way, different patterns with spatial overlapping can be selectively displayed with structural color. This technique may find applications in the fields of anti-counterfeiting, color display, decoration, encryption and optical data storage.

Keywords: Femtosecond laser pulses; Ripples; Structural colors

A comparative evaluation of surface morphology, cohesive and adhesive properties of one-step and two-step thermal deposited chromium thin films on glass substrates by A. Lazauskas; V. Grigaliūnas; F. Ecarla; M. Caunii (pp. 7633-7638).

► The two-step thermal deposition of chromium thin films followed by O₂ plasma treatment after the first deposition improved adhesion and cohesion of a film/substrate composite as compared with typical thin film deposition process. ► The cohesive failure of the multilayered chromium film influenced by more contact-wear-resistant surface morphology increased from 81±8mN to 165±10mN. ► Adhesion to the substrate was improved and critical adhesive loads were increased from 198±5mN to 221±5mN with less eruption of the film due to multilayer boundaries.The surface morphology, cohesive and adhesive properties of one-step and two-step thermal deposited chromium thin films are investigated. Surface characterization is followed by the atomic force microscopy topography images, surface morphology parameters, height distribution histograms and bearing ratio curves with hybrid parameters. Cohesive and adhesive properties of the deposited chromium thin films were evaluated by scratch tests using the progressive loading followed with optical microscopy inspection. The two-step thermal deposition of chromium thin films followed by O₂ plasma treatment after the first deposition gives better mechanical strengths as compared with conventional thermal deposition process. The changes involved in reflectance behavior of the films in UV/vis range are discussed.

Keywords: Chromium films; Thermal deposition; Oxygen plasma; AFM; Scratch test

Thermal laser micro-adjustment using picosecond pulse durations by J. Griffiths; S.P. Edwardson; G. Dearden; K.G. Watkins (pp. 7639-7643).

► Laser based micro-adjustment technique developed. ► Accurate and repeatable micro-adjustment of component demonstrated. ► Large range of deformation achieved. ► Short pulse duration limits heat diffusion from irradiation zone. ► High repetition rate ensures sufficient localized temperature accumulation.Thermal laser micro forming (LμF) is a non-contact process for the precise adjustment of micro-scale metallic components. Micro-electronic systems often comprise functional components which require highly accurate micro-scale adjustment after fabrication. Such functional components are typically difficult to access and highly sensitive to mechanical force. The application of lasers offers the potential for controlled and repeatable micro-adjustment of these components in a contact free process.The use of a picosecond pulsed laser source reduces the heat diffusion depth when compared to longer pulse durations, resulting in less thermal loading of the bulk substrate. When combined with high repetition rates, localized heat accumulation in micro-scale components can be achieved and utilized in a thermal forming process.In this work, the micro-adjustment of 1000μm×300μm stainless steel actuator arms using a mode locked fibre laser with a maximum pulse energy and duration of 3μJ and 20ps respectively was conducted. The effect of pulse overlap, laser power, irradiation strategy and number of irradiations on the net bend angle is presented.

Keywords: Micro-adjustment; Laser forming; Temperature gradient mechanism (TGM); MEMS

One-step synthesis of visible active CNS-tridoped TiO₂ photocatalyst from biomolecule cystine by Xiuwen Cheng; Xiujuan Yu; Zipeng Xing (pp. 7644-7650).

► CNS-tridoped TiO₂ has been synthesized by the addition of biomolecule cystine. ► This biomolecule cystine could be served as the sources of C, N and S simultaneously. ► The separation of photoinduced charge carriers and light absorption were improved. ► The activity enhanced mechanism was discussed in detail. ► This study provides a new strategy to synthesize visible light photocatalyst.CNS-tridoped TiO₂ nano-particles were synthesized through simple one-step sol–gel reactions in the presence of biomolecule cystine. This biomolecule could not only serve as the source for C, N and S tridoping, but also could control the light absorption in visible region and separation efficiency of photogenerated charge carriers. The resulting materials were characterized by X-ray diffraction (XRD), Nitrogen adsorption–desorption, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and surface photovoltage spectrum (SPS). It was found that S⁶⁺ was incorporated into the lattice of TiO₂ through substituting titanium atoms; N might coexist in the forms of substituted N (NOTi) and interstitial N (OTiN) in TiO₂; and C could form a mixed layer of carbonate on the surface of TiO₂. Further, the addition of cystine greatly improved the light absorption in visible region and the separation efficiency of photogenerated charge carriers. The photocatalytic activities of the as-synthesized samples were evaluated for the degradation of phenol under simulated sunlight irradiation. Results showed that CNS-tridoped TiO₂ exhibited higher sunlight photocatalytic degradation efficiency than that of undoped and P25 TiO₂ samples. The enhanced photocatalytic activity could be attributed to the small crystallite size, intense light absorption in visible region, large amount of surface hydroxyl groups and high separation efficiency of photogenerated charger carriers.

Keywords: Cystine; C; N; S-tridoped TiO; ₂; Photocatalysis; Phenol

Retardation of surface corrosion of biodegradable magnesium-based materials by aluminum ion implantation by Guosong Wu; Ruizhen Xu; Kai Feng; Shuilin Wu; Zhengwei Wu; Guangyong Sun; Gang Zheng; Guangyao Li; Paul K. Chu (pp. 7651-7657).

► Al ion implantation retards the surface bio-corrosion of pure Mg as well as AZ31 and AZ91 Mg alloys. ► Good initial corrosion resistance can be achieved in an Mg alloy with a low total content of Al. ► Al ion implantation produces a new oxide/metal surface gradient structure.Aluminum ion implantation is employed to modify pure Mg as well as AZ31 and AZ91 magnesium alloys and their surface degradation behavior in simulated body fluids is studied. Polarization tests performed in conjunction with scanning electron microscopy (SEM) reveal that the surface corrosion resistance after Al ion implantation is improved appreciably. This enhancement can be attributed to the formation of a gradient surface structure with a gradual transition from an Al-rich oxide layer to Al-rich metal layer. Compared to the high Al-content magnesium alloy (AZ91), a larger reduction in the degradation rate is achieved from pure magnesium and AZ31. Our results reveal that the surface corrosion resistance of Mg alloys with no or low Al content can be improved by Al ion implantation.

Keywords: Magnesium alloys; Biomaterials; Ion implantation; Corrosion; Surface

Influence of Eu doping on the microstructure and photoluminescence of CdS nanocrystals by Kexin Zhang; Yaxin Yu; Shuqing Sun (pp. 7658-7663).

►Eu³⁺ ions doped CdS nanocrystals bright a strong white emission. ► Several factors influence on optical properties of the CdS:Eu nanocrystals were discussed. ► The excellent stability of CdS:Eu nanocrystals have been demonstrated.The CdS:Eu nanocrystals with a strong white emission have been synthesized by solvothemal method using ethylene glycol as solvents. From X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) analysis it was observed that the average diameter of the CdS:Eu nanocrystals is about 5nm. The traces of groups adsorbed on CdS:Eu nanocrystals were confirmed via FT-IR spectra. UV–visible spectroscopy study was carried out to determine the band gap of the nanocrystals and the absorbance peaks showed blue shift with respect to the bulk CdS. From photoluminescence (PL) studies at λ_ex=398nm, the PL emission intensity of CdS:Eu nanocrystals enhanced by doping Eu³⁺ ions. In addition, the synthesis parameters including the concentration of doped Eu³⁺ ions, the reaction time, and the reaction temperature have influence on the optical properties of CdS:Eu nanocrystals. The charge compensation agent is a decisive factor for PL emission intensity of CdS:Eu nanocrystals. Furthermore, the storage time and condition on the fluorescence of CdS:Eu nanocrystals were also investigated.

Keywords: Nanocrystals; Doped; CdS:Eu; Photoluminescence characteristics

Segregation and morphology on the surface of ferritic stainless steel (001) by H. Fujiyoshi; T. Matsui; J. Yuhara (pp. 7664-7667).

► We studied the segregation and morphology on the surface of ferritic stainless steel (001) by STM, LEED, AES, and LEELS. ► At 500°C, segregated oxygen on ferritic steel (001) surface formed Cr₄O₅. ► At 600°C, carbon and chromium co-segregated to on the surface, forming the CrC structure. ► At 700°C, nitrogen segregated to the surface, forming the CrN structure.The temperature dependence of the segregation and morphology of ferritic steel (001) surfaces has been examined by a combination of Auger electron spectroscopy, low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and low-energy electron loss spectroscopy. Upon annealing ferritic steel at 500°C, the topmost layer was observed to be mainly composed of Fe–Cr alloy. Oxygen segregation was also detected locally in the STM images. LEED showed a (1×1) pattern and a weak (√5×√5)R27° reconstruction corresponding to Fe and Cr₄O₅, respectively. Upon annealing at 600°C, carbon and chromium co-segregated to the surface, forming two different regions composed of CrC and Cr-based steel, while the Cr₄O₅ domains disappeared. Upon annealing at 700°C, nitrogen segregated to the surface, and the topmost layer was observed to be mainly composed of CrN domains with local CrC domains.

Keywords: Surface segregation; Ferritic steel; Oxide; Nitride; Carbide; Scanning tunneling microscopy

Piezoelectric β-polymorph formation and properties enhancement in graphene oxide – PVDF nanocomposite films by M. El Achaby; F.Z. Arrakhiz; S. Vaudreuil; E.M. Essassi; A. Qaiss (pp. 7668-7677).

Display Omitted► Bulk graphite oxide was exfoliated into graphene oxide nanosheets in DMF solvent. ► PVDF/graphene oxide nanocomposite films were prepared via solution coating method. ► Graphene oxide was homogeneously dispersed and distributed within PVDF matrix. ► PVDF nanocomposite films exhibit a purely β-phase at very low graphene oxide content. ► Tensile properties of PVDF nanocomposites were significantly improved.Graphene oxide nanosheets (GOn)/PVDF nanocomposite films were prepared by solution casting method with various GOn contents. GOn were obtained via sonication of bulk graphite oxide in dimethylformamide (DMF). Due to the strong and specific interaction between carbonyl group (CO) in GOn surface and fluorine group (CF₂) in PVDF, the GOn were homogeneously dispersed and distributed within the matrix. The chosen approach for preparation and the high compatibility between GOn and PVDF result in the formation of purely piezoelectric β-polymorph at only 0.1wt.% GOn content. Below that content a mixture of β and α-polymorph is observed. The Young's modulus and tensile strength of PVDF were respectively increased by 192% and 92% with the addition of 2wt.% GOn. The thermal stability of PVDF polymer was also significantly increased with increasing of GOn loading. The as-obtained flexible nanocomposite films with such low GOn content can be used as active materials in the field of piezoelectric applications.

Keywords: Graphene oxide; Solution casting method; β-Polymorph; PVDF nanocomposite films; Mechanical properties

Preparation of Cu₂ZnSnS₄ thin films by sulfurizing stacked precursor thin films via successive ionic layer adsorption and reaction method by Zhenghua Su; Chang Yan; Kaiwen Sun; Zili Han; Fangyang Liu; Jin Liu; Yanqing Lai; Jie Li; Yexiang Liu (pp. 7678-7682).

► We fabricated Cu₂ZnSnS₄ films by sulfurizing stacked films via SILAR method. ► The CZTS thin films have kesterite structure and p-type conduction. ► The CZTS thin films have good optical and electrical properties for solar cells. ► The SILAR method is quite simple and low-cost to prepare CZTS thin films.Earth-abundant Cu₂ZnSnS₄ is a promising alternative photovoltaic material which has been examined as absorber layer of thin film solar cells. In this study, Cu₂ZnSnS₄ (CZTS) thin films have been successfully fabricated by sulfurizing stacked precursor thin films via successive ionic layer adsorption and reaction (SILAR) method. The prepared CZTS thin films have been characterized by X-ray diffraction, energy dispersive spectrometer, Raman spectroscopy, UV–vis spectroscopy, Hall effect measurements and photoelectrochemical tests. Results reveal that the thin films have kesterite structured Cu₂ZnSnS₄ and the p-type conductivity with a carrier concentration in the order of 10¹⁸cm⁻³ and an optical band gap of 1.5eV, which are suitable for applications in thin film solar cells.

Keywords: Cu; ₂; ZnSnS; ₄; Thin film; SILAR; Solar cell

Preparation and characterization of inorganic–organic trilayer core–shell polysilsesquioxane/polyacrylate/polydimethylsiloxane hybrid latex particles by Ruiqin Bai; Teng Qiu; Feng Han; Lifan He; Xiaoyu Li (pp. 7683-7688).

Display Omitted► Functional polysilsesquioxane latex particles were prepared. ► Acrylate monomers and octamethylcyclotetrasiloxane grafted onto polysilsesquioxane. ► The obtained hybrid latex particles had trilayer core–shell structure. ► The hybrid latex film exhibited high hydrophobicity and low water absorption.The inorganic–organic trilayer core–shell polysilsesquioxane/polyacrylate/polydimethylsiloxane hybrid latex particles have been successfully prepared via seeded emulsion polymerization of acrylate monomers and octamethylcyclotetrasiloxane (D₄) gradually, using functional polymethacryloxypropylsilsesquioxane (PSQ) latex particles with reactive methacryloxypropyl groups synthesized by the hydrolysis and polycondensation of (3-methacryloxypropyl)trimethoxysilane in the presence of mixed emulsifiers as seeds. The FTIR spectra show that acrylate monomers and D₄ are effectively involved in the emulsion copolymerization and formed the polydimethylsiloxane-containing hybrid latex particles. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) confirm that the resultant hybrid latex particles have evident trilayer core–shell structure and a narrow size distribution. XPS analysis also indicates that polysilsesquioxane/polyacrylate/polydimethylsiloxane hybrid latex particles have been successfully prepared and PDMS is rich in the surface of the hybrid latex film. Additionally, compared with the hybrid latex film without PDMS, the hybrid latex film containing PDMS shows higher hydrophobicity (water contact angle) and lower water absorption.

Keywords: Trilayer; Core–shell; Polysilsesquioxane; Polyacrylate; Polydimethylsiloxane; Hybrid latex particles

A density functional study of NO₂ adsorption on perfect and defective MgO (100) and Li/MgO (100) surfaces by Kh.M. Eid; H.Y. Ammar (pp. 7689-7698).

► Adsorption properties of Li atom on various sites of MgO (100) surface. ► The characteristics of the NO₂ molecule adsorption on various sites of MgO (100) surface before and after supported Li atom. ► The presence of Li atom enhances the adsorption processes of NO₂ on MgO(O²⁻) substrate surfaces. ► The existence of Li atom does not sustain the adsorption processes of NO₂ on MgO ( F_s and F_s⁺). ► The presence of Li atom converts the adsorption of NO₂ on MgO(O²⁻) substrate surfaces from physisorption to chemisorptions.The density functional theory (DFT) in combination with embedded cluster model have been used to study the adsorption of nitrogen dioxide molecule (NO₂) on Li atom deposited on the surfaces of metal oxide MgO (100) on both anionic (O²⁻) and defect ( F_s and F_s⁺-centers) sites. The adsorption energy ( E_ads) of NO₂ molecule (N-down as well as O-down) in different positions on O⁻², F_s and F_s⁺-sites is considered. The geometrical optimizations have been done for the additive materials and MgO substrate surfaces. The formation energies have been evaluated for F_s and F_s⁺ of MgO substrate surfaces. The ionization potential (IP) and electron affinity (eA) for defect free and defect containing surfaces have been calculated. The adsorption properties of NO₂ are analyzed in terms of the adsorption energy, the electron donation (basicity), the elongation of NO bond length and the atomic charges on adsorbed materials. The densities of states (DOS) have been calculated and used for examining the adsorption properties. The NO₂ molecule is dissociated due to the interaction with the defective substrate surface ( F_s-site) producing an oxygen atom strongly chemisorbed to the vacancy of the substrate and gaseous NO far away from the surface. The presence of the Li atom increases the surface chemistry of the anionic O²⁻-site of MgO substrate surfaces (converted from physisorption to chemisorption). On the other hand, the presence of the Li atom decreases the surface chemistry of the F_s and F_s⁺-sites of MgO substrate surfaces. Generally, the NO₂ molecule is strongly adsorbed (chemisorption) on the MgO substrate surfaces containing F_s and F_s⁺-centers.

Keywords: Adsorption of NO; ₂; Chemisorption; MgO surfaces; Density-functional theory; Dissociation of NO; ₂; F; _s; and; F; _s; ⁺; -centers

Friction and wear behaviors of compacted graphite iron with different biomimetic units fabricated by laser cladding by Na Sun; Hongyu Shan; Hong Zhou; Darong Chen; Xiaoyan Li; Wen Xia; Luquan Ren (pp. 7699-7706).

► Fabricating biomimetic units to form wear resistant surfaces by laser cladding. ► Investigating four different cladding ceramics on friction and wear of biomimetic specimens. ► Reinforced microstructure of biomimetic unit is the main contribution to wear resistance. ► Cladding TiC is the best in anti-wear while cladding B₄C is the highest in friction coefficient.Mimicking the biological characters on the cuticles of pangolin scales, biomimetic units were fabricated on the surfaces of compacted graphite cast iron (CGI) with different unit materials using laser cladding process. The influences of various unit materials including TiC, WC, B₄C and Al₂O₃ powders on the friction and wear behaviors of CGI were investigated. The wear resistance mechanism of biomimetic specimens was discussed. The results indicated that the wear resistance of biomimetic specimens cladding TiC was the best; the specimens cladding WC or B₄C were in the middle; and the specimens cladding Al₂O₃ was the worst. The sequence of friction coefficient values of biomimetic specimens cladding different ceramic powders from high to low was B₄C, TiC, WC and Al₂O₃. The wear mechanism of untreated specimen was mainly adhesion wear, abrasive wear as well as the oxidation wear, whereas the adhesive wear and abrasive wear was the main wear mechanism of the regions of substrate in biomimetic specimens and slight adhesion, abrasive wear and fatigue wear on the regions of biomimetic units.

Keywords: Biomimetic; Compacted graphite iron; Microstructure; Friction and wear; Laser cladding

Magnetoactive feature of in-situ polymerised polyaniline film developed on the surface of manganese–zinc ferrite by V. Babayan; N.E. Kazantseva; I. Sapurina; R. Moučka; J. Vilčáková; J. Stejskal (pp. 7707-7716).

► In-situ grown PANI film on the surface of MnZn ferrite exhibits magnetoactive properties. ► Ferrite accelerates PANI growth by sorption of paramagnetic anilile oligomers on domain walls. ► Pinning of domain walls restricts their mobility in magnetic fields. ► Pinning forces are strong enough to induce magnetic anisotropy in low-anisotropy MnZn ferrite. ► Stress-induced magnetic anisotropy increases inner demagnetising factor of coated ferrite particles.A polyaniline film exhibits magnetoactive properties when deposited on the surface of multidomain particles of manganese–zinc ferrite during in-situ polymerisation of aniline. This is reflected in the increased coercivity and thermomagnetic stability of an in-situ prepared composite compared with bare ferrite and its mixed composite with polyaniline. In addition, the deposition of a polyaniline film results in a shift of the complex-permeability dispersion region towards ultrahigh frequency band. These changes in the magnetic properties of polyaniline-coated ferrite are attributed to the increased value of the inner demagnetisation factor, which results from stress-induced magnetic anisotropy due to the pinning of domain walls appearing on the surface of ferrite. This study is focused on the mechanism of pinning of domain walls and its influence on the magnetic properties of in-situ prepared composites in terms of the molecular mechanism of oxidative polymerisation of aniline. Ferrite stimulates the propagation of polyaniline chains, which start to grow on the domain walls on the ferrite surface. It leads to the pinning of domain walls and restricts their mobility in a magnetic field. The further increase in the coercivity and the resonance frequency of polyaniline-coated ferrite due to film shrinkage after deprotonation of polyaniline makes it obvious that polyaniline coating induces elastic stresses in a ferrite particle that stimulate the growth of the effective magnetic anisotropy. Stress-induced magnetic anisotropy contributes to the reorientation of the magnetisation vectors in domains with respect to the new directions of easy magnetisation, given by magnetoelastic stresses, which leads to complex changes in the magnetic properties of in-situ prepared composites.

Keywords: Ferrite; Polyaniline; Core–shell particles; Coercivity; Complex magnetic permeability; Induced magnetic anisotropy; Inner demagnetisation factor

Ripple topography and roughness evolution on surface of polycrystalline gold and silver thin films under low energy Ar-ion beam sputtering by Patrick Gailly; Claire Petermann; Pierre Tihon; Karl Fleury-Frenette (pp. 7717-7725).

► Ripple topography measured on gold and silver films sputtered with Ar⁺ 650eV is compared to theory. ► Ripples were always oriented parallel to the ion beam direction. ► Ripples wavelength decreased with increasing energy and ion flux. ► Three regimes for roughness evolution have been observed as function of the angle of incidence. ► The lower roughness observed around 45° on gold and 60° on silver films is promising for polishing applications.Metallic thin films of gold and silver have been sputtered by argon ions at low energy in the framework of technological applications including nanostructuring and ion beam figuring. Ion beam sputtering at high angle of incidence usually leads to spontaneous formation of periodic structures on the target surface, commonly referred as ripples. In this work, ripples dimensions and roughness evolution have been studied as function of the angle of incidence (0–80°), ion beam energy (400–1200eV) and ion flux. The ripple wave vector direction was always observed perpendicular to the ion beam direction for both materials, in agreement with theoretical predictions for the investigated experimental conditions. The decrease of ripple wavelength with energy and ion flux shows the dominance of thermal diffusion as smoothing mechanism. Moreover, three regimes for roughness evolution on gold and silver films have been observed as function of the angle of incidence for sputtering at 650eV, with a minimum roughness achieved around 45° and 60° for gold and silver, respectively.

Keywords: Sputtering; Ripples; Roughness; Topography; Metallic thin films; Ion beam figuring

IR study of fundamental chemical reactions in atomic layer deposition of HfO₂ with tetrakis(ethylmethylamino)hafnium (TEMAH), ozone, and water vapor by F. Hirose; Y. Kinoshita; K. Kanomata; K. Momiyama; S. Kubota; K. Hirahara; Y. Kimura; M. Niwano (pp. 7726-7731).

► Fundamental reactions of HfO₂ ALD with TEMAH and ozone on Si (100) surfaces at room temperature were studied. ► TEMAH is possible to adsorb at OH sites on water adsorbed Si surfaces at room temperature. ► The ozone irradiation on the TEMAH adsorbed Si surface at room temperature is effective in removing hydroaminocarbon adsorbates. ► A water vapor treatment at around 160°C is effective in restoring the adsorption sites. ► HfO₂ ALD was achieved with a growth temperature of 160°C.The fundamental reactions in HfO₂ atomic layer deposition (ALD) with the precursors tetrakis(ethylmethylamino)hafnium (TEMAH), ozone, and water vapor on Si (100) surfaces at room temperature (RT) were studied by infrared absorption spectroscopy (IRAS) with a multiple internal reflection geometry. The IRAS results indicated that TEMAH can be adsorbed at OH sites on Si surfaces at RT. Ozone irradiation on the TEMAH-adsorbed Si surface at RT effectively removes hydroaminocarbon adsorbates introduced in the course of TEMAH adsorption, although this treatment provides no OH-group adsorption sites for TEMAH on the Si surface at RT. For further adsorption, water–vapor treatment at around 160°C is effective in restoring the adsorption sites. The IR study suggests that the cyclic process of TEMAH adsorption and ozone treatment at RT followed by OH restoration with water vapor at a temperature of 160°C allows continuous HfO₂ deposition.

Keywords: HfO2; Atomic layer deposition; IR absorption spectroscopy

Adsorption of copper and nickel ions on macroporous chitosan membrane: Equilibrium study by A. Ghaee; M. Shariaty-Niassar; J. Barzin; A. Zarghan (pp. 7732-7743).

► The competitive adsorption of Cu and Ni ions on chitosan membrane was investigated. ► Experiments showed the chitosan membrane has higher affinity for Cu²⁺ than Ni²⁺. ► Mono and bi-metal adsorption isotherms fitted with various optimization methods. ► Cu and Ni adsorption mechanism is chelation together with electrostatic adsorption.The competitive adsorption of copper and nickel ions on macroporous chitosan membrane was investigated for the first time in this research. At first macroporous chitosan membrane was prepared by particulate leaching out method. Membrane surface chemical characterization was analyzed by ATR and EDX. Batch adsorption experiments were carried out with mono and binary component solutions on chitosan membrane. In mono-component adsorption, the copper ions adsorption was 19.87mg/g which was higher than those of the nickel (i.e. 5.21mg/g), while the initial concentrations in both cases were the same. Comparing bi-component with mono-component adsorption, the competitive adsorption caused a reduction in the adsorption of individual ions. To obtain the mono and bi-component adsorption equilibrium models’ parameter, several optimization methods were used and their results were compared. Mono and binary component adsorption models were fitted the experimental data well; also adsorption kinetic studies were performed for macroporous chitosan membrane. Desorption experiments were studied using EDTA as eluant.

Keywords: Chitosan; Adsorption; Copper; Nickel; Isotherm

Modeling the electroless nickel deposition on aluminum nanoparticles by H. Beygi; H. Vafaeenezhad; S.A. Sajjadi (pp. 7744-7750).

► Ni coated aluminum nanoparticles fabricated by electroless nickel (EN) deposition. ► Investigating on composition and parameters of EN, efficient EN bath modeled by ANN. ► Maximum plating rate and minimum material usage are considered as desired outcomes. ► Optimum NiSO₄·2H₂O/NaH₂PO₂·H₂O ratio to design any EN bath estimated about 0.35. ► Thin and uniform Ni shell within about 30nm thickness coated Al nanoparticles.In this study, Ni coated aluminum nanoparticles were fabricated by electroless nickel deposition. Effect of two groups of parameters on the process plating rate were investigated: bath composition (main salt, reducing agent and complexing agent concentration) and process parameters (pH, plating time and bath temperature). Simulation of the process was performed using artificial neural network (ANN) media. Based on the presented model it is possible to design a high efficiency electroless bath, while minimum received materials are used and maximum plating rate is obtained. According to the model's results, 0.07mol/l NiSO₄·2H₂O, 0.245mol/l NaH₂PO₂·H₂O and 0.098mol/l Na₃C₆H₅O₇·H₂O were chosen as the optimum electroless bath composition. The optimum bath parameters also were selected as pH of 9.5, temperature of 80°C and 30min of plating. At such condition, the most efficient Ni deposition, with maximum plating rate of 45%, was acquired on the surface of aluminum particles. These samples were characterized by scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results showed that a low phosphorus and nanocrystalline Ni layer, with about 30nm thickness, has been coated on the aluminum nanoparticles.

Keywords: Aluminum nanoparticle; Electroless nickel deposition; Artificial neural network (ANN)

Growth of graphene-like thin films at low temperature by dual-frequency capacitively coupled plasma by Yijun Xu; Xuemei Wu; Chao Ye (pp. 7751-7754).

► We developed a new method of growing graphene-like thin films on glass substrates. ► Dual-frequency capacitively coupled plasma (DF-CCP) enhanced chemical vapor deposition (CVD) was used as the film growing method. ► Graphene-like films were grown at low temperature without using any metallic catalyst. ► The defects of films could be decreased and the crystal structure could be improved effectively by annealing treatment.Growth of graphene-like films at low temperature on 2cm×2cm glass substrate without using any metallic catalyst was developed by dual-frequency capacitively coupled plasma (DF-CCP) enhanced chemical vapor deposition (CVD), and then annealed at 300–500°C. Transmittance measurement indicates the thin films were about two layers. Raman spectroscopy not only confirms the sp²-C structure but also reveals the high defect densities in the as-deposited thin films. The calculated crystalline length of the as-deposited films is 55.97nm. However, after annealing treatment the defects can be decreased and the crystalline length increased to maximum of 149.25nm. Therefore, the high quality graphene-like thin films can be obtained at low temperature.

Keywords: Graphene-like films; DF-CCP; CVD; Annealing

Effects of SF₆/Ar gas-mixing ratio on the etching behavior and properties of BZN thin films by L.P. Dai; G.J. Zhang; S.Y. Wang; Z.Q. Zhong; G. Wang (pp. 7755-7759).

► We study films surface etch rate with gas mixing ratio variation by error bars. ► We study films surface etch reaction and compositions with gas mixing ratio by XPS. ► We study films surface morphology and dielectric property with gas mixing ratio. ► The results are important and instructive for further etching.Bismuth zinc niobate (BZN) thin films were etched as a function of the SF₆/Ar gas-mixing ratio in a reactive-ion etching (RIE) system. The etching characteristics of surface etch rate and compositions were investigated. Within the ratio range of choice, the etch rate of BZN films is found to decrease first and then increase as the ratio decreases. The small error bars shown in the line graph present a high reliability of the etch rate data. BZN films surfaces were investigated by X-ray photoelectron spectroscopy (XPS). Metal fluorides were found to remain in the surface, resulting in varying relative atomic percentages with gas-mixing ratio. Zn-rich surfaces were formed for ZnF₂ residues were hard to remove. Bi and Nb can be removed easily through chemical reactions because of their high volatility, while BiF and NbF can be still detected using narrow scan spectra, which were thought to be present in the form of a metal-oxy-fluoride (Metal-O-F). Gas-mixing ratio is found to have an effect on etch reaction and the removal of residues through different plasma ratios etch process, therefore, leading to varying compositions and element chemical binding state, and resulting in the AFM surface morphology and dielectric property variation. The minimum value of F atomic concentration is achieved at SF₆/Ar ratio of 32/13, while the lower surface roughness and the greater dielectric constant both appear at the ratio of 40/5.

Keywords: BZN; Reaction ion etching; XPS; Plasma

Dependence of structural and optical properties of sol–gel derived ZnO thin films on sol concentration by Linhua Xu; Gaige Zheng; Juhong Miao; Fenglin Xian (pp. 7760-7765).

► ZnO thin films have been prepared by sol–gel method using various sol concentrations. ► The ZnO thin films deposited in this study had approximately equal thickness, excluding the influence of film thickness on the physical properties. ► The results showed that low sol concentration was favorable for obtaining high c-axis oriented ZnO thin films with good crystalline quality. ► Photoluminescence spectra indicated that the defect-related blue emission was increased with the enhancement of sol concentration.In this work, ZnO thin films were prepared by sol–gel method and the dependence of structural and optical properties of these films on sol concentrations was deeply investigated. Unlike the previous studies, the ZnO thin films deposited in this study have approximately equal thickness, which excludes the influence of film thickness on the physical properties. The results show that low sol concentration is favorable for obtaining high c-axis oriented ZnO thin films with good crystalline quality. When the sol concentration is above 0.7mol/L, the degree of c-axis orientation of ZnO thin films decreases and the optical quality is also degraded. Photoluminescence spectra indicate that the defect-related blue emission is increased with the enhancement of sol concentration. The mechanism of the blue emission is analyzed. The reason why high sol concentration is unfavorable for formation of high c-axis oriented ZnO thin films and obtaining high optical quality is also discussed.

Keywords: PACS; 78.20.a; 78.30.Fs; 78.55.−m; 81.20.FwZnO thin film; Sol–gel method; Sol concentration; Optical band gap; Photoluminescence

Infrared long nanosecond laser pulse ablation of silicon: Integrated two-dimensional modeling and time-resolved experimental study by Sha Tao; Yun Zhou; Benxin Wu; Yibo Gao (pp. 7766-7773).

► Infrared laser ablation of silicon is studied through modeling and experiments. ► Silicon vaporization yields plume with non-uniform radiation intensity. ► Radiation intensity distribution is consistent with and explained by the model. ► Silicon liquid ejection is due to surface pressure variation and distribution.Nanosecond (ns) laser ablation may provide good solutions to many industrial silicon micromachining applications. However, most of the previous work is on lasers in ultraviolet (UV) or visible spectral ranges, and ns laser ablation of silicon at the infrared (IR) wavelength has not been well understood, particularly for long ns pulses with durations on the order of ∼100ns. IR ns lasers often have lower costs and less external energy consumption for the same laser energy output than UV or visible lasers, which is desirable for many practical applications. This paper aims to understand the mechanism of IR ns laser ablation of silicon, by combining time-resolved experimental observations with physics-based modeling study. The observation is through a ns-gated intensified charged-coupled devices (ICCD) camera coupled with a microscope tube, while the model is based on two-dimensional (2D) gas dynamic equations for the gaseous phases coupled with the condensed phase heat transfer equation through the Knudsen layer relations. The research shows that the material removal mechanism under the studied laser ablation conditions is surface vaporization in the early stage (yielding a plasma plume above the target), followed by subsequent liquid ejection. The measured plasma front propagation matches reasonably well with the model prediction. The experimentally observed spatial distribution of the plasma radiation intensity is consistent with and has been understood through the model. The study also shows that the observed liquid ejection is induced by the total surface pressure difference between the near-boundary region of the target melt pool and the other remaining region of the pool. The pressure difference is mainly due to the surface vaporization flux drop after laser pulse ends.

Keywords: Laser ablation; Laser micromachining

Preparation and characterization of monodispersed PS/Ag composite microspheres through modified electroless plating by Yuehui Ma; Qinghua Zhang (pp. 7774-7780).

Display Omitted► PS/Ag composite microspheres have great potential to be used as fillers of ACFs. ► Uniform colloidal Pt of approximate 10nm is used as catalytic centers. ► Increasing concentration of silver precursors enables growth of silver shell. ► PVP used as stabilizer to protect PS/Ag microspheres from aggregation. ► Monodispersed PS/Ag composite microspheres have good conductivity.A modified electroless silver-plating process has been devised for the preparation of monodispersed, polystyrene/silver (PS/Ag) composite microspheres with tunable shell thickness. Tailoring was achieved by altering the concentration of the silver precursor in the plating bath. PS/Ag composite microspheres were characterized by field-emission scanning electron microscopy, ultraviolet–visible absorption, X-ray diffraction and thermogravimetric analysis. The results showed that a dense, stable and uniform silver nanoshell was formed on the surface of PS microspheres in the presence of poly(vinylpyrrolidone) and glucose. The bulk conductivity of the PS/Ag composites increased from 1.16S/m to 3.57×10⁴S/m, corresponding to a shell thickness of 35–198nm. The PS/Ag composite microspheres with diameters of ca. 3μm might have great potential to be used as fillers in anisotropic conductive films because of the uniform diameter, low density and good conductivity of the microspheres.

Keywords: Composite microspheres; Electroless plating process; Conductive filler

Fabrication of free-standing copper foils covered with highly-ordered copper nanowire arrays by Leszek Zaraska; Grzegorz D. Sulka; Marian Jaskuła (pp. 7781-7786).

► Through-hole AAO membranes are fabricated by anodizing of Al in acidic electrolytes. ► AAO templates are employed for fabrication of free-standing cooper foils covered with highly-ordered Cu nanowire arrays. ► As prepared nanostructured electrodes are mechanically stable and easy to handle.The through-hole nanoporous anodic aluminum oxide (AAO) membranes with relatively large surface area (ca. 2cm²) were employed for fabrication of free-standing and mechanically stable copper foils covered with close-packed and highly-ordered copper nanowire arrays. The home-made AAO membranes with different pore diameters and interpore distances were fabricated via a two-step self-organized anodization of aluminum performed in sulfuric acid, oxalic acid and phosphoric acid followed by the pore opening/widening procedure. The direct current (DC) electrodeposition of copper was performed efficiently on both sides of AAO templates. The bottom side of the AAO templates was not insulated and consequently Cu nanowire arrays on thick Cu layers were obtained. The proposed template-assisted fabrication of free-standing copper nanowire array electrodes is a promising method for synthesis of nanostructured current collectors. The composition of Cu nanowires was confirmed by energy dispersive X-Ray spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The structural features of nanowires were evaluated from field emission scanning electron microscopy (FE-SEM) images and compared with the characteristic parameters of anodic alumina membranes.

Keywords: Anodization; Porous alumina; Nanowires; Electrodeposition

The application of He/O₂ atmospheric pressure plasma jet and ultrasound in desizing of blended size on cotton fabrics by Xuming Li; Yiping Qiu (pp. 7787-7793).

► The removal of the blend of PVA and starch phosphate treated by plasma and ultrasound is studied. ► The change of surface morphology and surface chemical composition of blends treated by plasma were studied. ► The influence of plasma and ultrasound treatment on the percent desizing ratio (PDR) is investigated, respectively. ► The capillary rise height is used to study the wicking properties after plasma and ultrasound desizing.This study investigates the influence of the He/O₂ atmospheric pressure plasma jet (APPJ) and ultrasound treatment on desizing of the blended sizes of starch phosphate and polyvinyl alcohol (PVA) on cotton fabrics. The AFM and SEM results indicate that APPJ treatment can increase the surface roughness of the sized fabrics. The SEM results also reveal that the fiber surfaces are nearly as clean as unsized fiber surfaces after 35s treatment followed by ultrasound desizing for 20min at 60°C. X-ray photoelectron spectroscopy (XPS) analysis indicates that oxygen-based functional groups increase on the surfaces of the plasma treated sized fabrics. The PDR of the sized fabrics treated by APPJ dramatically increases when ultrasound was introduced during the desizing process, and the desizing time and temperature are greatly reduced. Wickability analysis reveals that the capillary height of the fabrics treated by plasma and ultrasound was higher than that of the fabrics treated by plasma and hot washing under different plasma exposure time. Therefore, the combination of the APPJ and ultrasound has shown higher effectiveness in desizing and provides an alternative approach that decreases the water, energy and chemicals consumption.

Keywords: Atmospheric pressure plasma jet (APPJ); Ultrasound; Starch phosphate; Poly (vinyl alcohol) (PVA); Desizing; AFM; XPS; SEM

Erratum to “Defects, stress and abnormal shift of the (002) diffraction peak for Li-doped ZnO films” [Appl. Surf. Sci. 256 (2010) 7623–7627] by Yow-Jon Lin; Mu-Shan Wang; Chia-Jyi Liu; Hsueh-Jung Huang (pp. 7794-7794).

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Applied Surface Science (v.258, #19)

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Applied Surface Science (v.258, #19)