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Applied Surface Science (v.257, #15)

Effect of the laser fluence on the surface characterization of β-FeSi₂ films prepared by pulsed laser deposition by B.Y. Man; S.C. Xu; C. Yang; M. Liu; S.Z. Jiang; Y.Y. Ma; C.S. Chen; A.H. Liu; X.G. Gao; C.C. Wang; B. Hu (pp. 6321-6325).

► Single-phase semiconducting iron disilicide (β-FeSi₂) films on silicon (100) substrate were successfully fabricated by pulse laser deposition with different laser fluence. ► The structure and crystal quality of the samples were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. ► The film thickness was estimated by field scanning electron microscopy and it is found that the film thickness increases with the increasing of the laser fluence. ► Based upon all experimental results, it is found that 7J/cm² is the most favorable for the formation of single phase β-FeSi₂ thin films.Single-phase β-FeSi₂ films on silicon (100) were fabricated by pulse laser deposition. The structure and crystal quality of the samples were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The field scanning electron microscopy showed that the film thickness increases with the increasing of the laser fluence. Moreover, atomic force microscopy observations revealed the changes of surface properties with different laser fluence. Based upon all experimental results, it is found that 7J/cm² is the most favorable for the formation of β-FeSi₂ thin films.

Keywords: Pulse laser deposition; Laser fluence; Single-phase β-FeSi; ₂

Interactions between tri-methylaluminum molecules and their effect on the reaction of tri-methylaluminum with an OH-terminated Si (001) surface by Dae-Hee Kim; Seung-Bin Baek; Hwa-Il Seo; Yeong-Cheol Kim (pp. 6326-6331).

► Interactions between tri-methylaluminum molecules on OH-terminated Si (001) surface. ► High energy barriers due to interaction between the two molecules. ► Mixed surface chemistry at an intermediate surface temperature.We studied the interaction between tri-methylaluminum (Al(CH₃)₃, TMA) molecules and their effect on TMA reactions with a fully OH-terminated Si (001) surface for initial aluminum oxide thin-film growth using density functional theory. The reaction between an adsorbed TMA and the surface produced a di-methylaluminum (–Al(CH₃)₂, DMA) group, and further reaction to a uni-methylaluminum (–AlCH₃, UMA) group with energy barriers of 0.50 and 0.21eV, respectively. A second TMA adsorbed near the already adsorbed TMA, DMA, or UMA group showed higher energy barriers (0.68–1.01eV) for its reaction to produce a DMA group due to the interaction between them. Therefore, the fully OH-terminated Si (001) surface would be covered by the mixture of the adsorbed TMA and UMA groups at an intermediate surface temperature.

Keywords: ALD; Al; ₂; O; ₃; Tri; -methylaluminum; Density functional theory

Field emission property of printed CNTs-mixed ZnO nanoneedles by Yu Ling-min; Fan Xin-hui; Qi Li-jun; Yan Wen (pp. 6332-6335).

► Field emission (FE) properties of screen printed ZnO nanoneedles could be enhanced by carbon nanotubes mixture. ► The highest field emission property of CNT-mixed ZnO nanoneedles was expressed by heat-treated at 450°C. ► The uniform distribution and great density of luminance point can be emitted from the screen printed CNT-mixed ZnO nanoneedles through heat treatment at 450°C.ZnO nanoneedles were synthesized via thermal evaporation method without any catalyst. Scanning electron microscopy and transmission electron microscopy investigations showed that these products presented a nanoneedle structure. To enhance the field emission (FE) properties of screen printed ZnO nanoneedles, a given amount (0.05g) carbon nanotubes (CNTs) mixed with (0.5g) ZnO nanoneedles paste via screen printed method and heat-treatment at (600°C, 500°C and 450°C) was presented. The CNTs-mixed ZnO nanoneedles heat-treated at 450°C had the lowest turn-on field of 3.75V/μm, highest field emission current of 0.16mA at 7.5V/μm and highest β of 830. An efficiency FE enhancement of 450°C sample was attributed to melioration of conductance between ZnO nanoneedles and ITO surface by CNTs.

Keywords: Field emission; Screen printing; ZnO nanoneedles; CNTs

Influence of growth time on field emission properties from carbon nanotubes deposited on arrayed nanoporous silicon pillars by Wei Fen Jiang; Hao Shan Hao; Yu Sheng Wang; Lei Xu; Tian Jie Zhang (pp. 6336-6339).

► We synthesized a composite structure–MWCNTs deposited on a silicon nanoporous pillar array. ► The influence of growth time on field emission properties was investigated. ► The sample grown for a middle time showed the best field emission performance. ► The nest array structure would result in a great enhancement factor. ► The medium CNTs density could avoid electrostatic shielding, along with a high emitter density.We investigated the influence of growth time on field emission properties of multi-walled carbon nanotubes deposited on silicon nanoporous pillar array (MWCNTs/Si-NPA), which were fabricated by thermal chemical vapour deposition at 800°C for 5, 15 and 25min respectively, to better understand the origins of good field emission properties. The results showed that the MWCNTs/Si-NPA grown for 15min had the highest field emission efficiency of the three types of samples. Morphologies of the products were examined by field-emission scanning electron microscope, and the excellent field emission performance was attributed not only to the formation of a nest array of multi-walled carbon nanotubes, which would largely reduce the electrostatic shielding among the emitters and resulted in a great enhancement factor, but also to the medium MWCNTs density films, there was an ideal compromise between the emitter density and the intertube distance, which also could effectively avoid electrostatic shielding effects, along with a high emitter density.

Keywords: Carbon nanotube; Field emission; Silicon nanoporous pillar array

Preparation and wear resistance of pulse electrodeposited Ni–W/Al₂O₃ composite coatings by Kung-Hsu Hou; Yann-Cheng Chen (pp. 6340-6346).

► A new coatings material of Ni–W/Al₂O₃ is developed. ► The Ni–W/Al₂O₃ coatings were manufactured by pulse electroplating technique. ► Tungsten content in coatings increased significantly with increasing duty cycle. ► Micro-hardness of 859Hv was obtained with W-40wt. % in Ni–W/Al₂O₃ coating.The aim of this work is to obtain the electroplating parameters for preparation of Ni–W/Al₂O₃ composite coating with high tungsten content, high micro-hardness and excellent wear resistance by pulse plating procedure. Our results showed that the duty cycle is a dominant parameter for the tungsten content in the coating and the tungsten content increases significantly with increasing duty cycle. The further analysis showed the great influence of tungsten content on micro-hardness of the coating. A maximum micro-hardness of about 859Hv was obtained in pulse electrodeposited Ni–W/Al₂O₃ composite with tungsten content of 40wt.% at a peak current density of 20A/dm², a duty cycle of 80%, a pulse frequency of 1000Hz and a particle loading of 10g/L alumina in the plating bath. Although the hardness of Ni–W/Al₂O₃ composite coating was only slightly affected by the alumina content of the deposits prepared in present investigation, the alumina content effect on the tribological characteristic of Ni–W/Al₂O₃ composite coatings is significant. The friction coefficient was lowered to 0.25 and the wear loss was reduced to 1.05mg by setting the control factors according to the values mentioned above for obtaining the coating with the highest micro-hardness.

Keywords: Pulse electrodeposition; Ni–W/Al; ₂; O; ₃; composite coating; Wear resistance

2-Amino-5-(4-pyridinyl)-1,3,4-thiadiazole film at the silver surface: Observation by Raman spectroscopy and electrochemical methods by Lijun Zhang; Ying Wen; Yingcheng Pan; Haifeng Yang (pp. 6347-6352).

► 2-Amino-5-(4-pyridinyl)-1,3,4-thiadiazole (4-APTD) as anticorrosive reagent. ► Adsorption of 4-APTD at the silver surface via N¹², S¹ and C² atoms to form film. ► Inhibition efficiency of silver with 4-APTD film is of 89.5% in 0.1M KCl solution.Surface enhanced Raman scattering (SERS) spectrum of the 2-amino-5-(4-pyridinyl)-1,3,4-thiadiazole (4-APTD) on the silver surface was recorded and assigned with the help of B3LYP/6-311G** method. SERS result explored that 4-APTD molecule with a tilted orientation anchored at the silver surface via N¹², S¹ and C² atoms. In situ SERS spectroelectrochemical experiment indicated 4-APTD molecule experienced an intermediate adsorption process of its thiadiazole ring moiety with the vertical orientation at the surface before the 4-APTD molecule detached completely from the surface as the potential applied at −1.3V vs. SCE. Electrochemical impedance spectroscopy (EIS) and polarization experiments exhibited the sound anticorrosive effect of the 4-APTD film on silver surface with an efficiency of 89.5%.

Keywords: 2-Amino-5-(4-pyridinyl)-1,3,4-thiadiazole; Silver; Raman; EIS; Electrochemical polarization

Exploration of bimetallic Pt-Pd/C nanoparticles as an electrocatalyst for oxygen reduction reaction by A. Maghsodi; M.R. Milani Hoseini; M. Dehghani Mobarakeh; M. Kheirmand; L. Samiee; F. Shoghi; M. Kameli (pp. 6353-6357).

Display Omitted► Synthesis of Pt/C and Pt-Pd/C electrocatalysts by using NaBH₄ reducing agent. ► Highly dispersed of Pd and Pt on the carbon support. ► Higher electrocatalytic activity of Pt-Pd/C in relative to Pt/C towards ORR.In this study, carbon supported Pt and Pt-Pd were synthesized as oxygen reduction reaction electrocatalysts for polymer electrolyte membrane fuel cells (PEMFCs). Pt and Pt-Pd nanoparticles have been synthesized by reduction of metal precursors in presence of NaBH₄. Various techniques such as X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX) and scanning electron microscopy (SEM) were utilized to study the prepared samples. Furthermore, electrochemical properties of the prepared samples were evaluated from cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry and electrochemical impedance spectroscopy (EIS). The results showed, the crystallite size of electrocatalysts (Pt and Pt-Pd) is below 10nm. The higher catalytic activity was detected for Pt-Pd/C electrocatalyst for oxygen reduction reaction (ORR). In addition, it is believed that the better performance of electrocatalyst is related to the synergic effect between Pt and Pd nanoparticles, weakening of the OO bond on Pd-modified Pt nanoparticles in ORR, uniform dispersion of Pd and Pt on the carbon support and higher electrochemical active surface area (EAS) of Pt-Pd/C electrocatalyst.

Keywords: Electrocatalyst; Polymer electrolyte membrane fuel cell; Oxygen reduction reaction (ORR); Nanoparticles

Synthesis and photocatalysis properties of ZnO structures with different morphologies via hydrothermal method by Juan Xie; Hu Wang; Ming Duan; Liehui Zhang (pp. 6358-6363).

► Different morphologies of ZnO as photocatalysis. ► The flower- and sheet-like structures are synthesized by hydrothermal method. ► The samples show different photocataloytic activities.The special flower-like and sheet-like ZnO structures were successfully synthesized by hydrothermal method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The photocatalytic activity of different morphologies of ZnO structures was evaluated by degradating of methyl orange (MO). The photocatalytic degradation process was monitored in terms of decolorization and total organic carbon (TOC) removals. The results indicated that the flower-like ZnO structures were consisted of numerous flower-like aggregates with the size of 2μm. The sheet-like ZnO nanostructures were obtained by increasing the reaction time. They exhibited higher photodegradation efficiencies under UV light irradiation than flower-like ZnO structures due to the blue shift of the band gap. The photodegradation could be described as the pseudo-first-order kinetics with apparent rate constants ranging from 1.17×10⁻² to 3.42×10⁻²min⁻¹, which were based on the morphology of the structures. The photodegradation was faster than the mineralization, indicating that the accumulation of by-products were resistant to photocatalytic degradation.

Keywords: ZnO; Hydrothermal method; Flower-like; Sheet-like; Photocatalytic

Electro-spark alloying using graphite electrode on titanium alloy surface for biomedical applications by Tang Chang-bin; Liu Dao-xin; Wang Zhan; Gao Yang (pp. 6364-6371).

► Electro-spark alloying (ESA) modification, as a potential promising method available was studied on Ti-alloy for biomedical applications. ► The ESA layer prepared in silicone oil show excellent wear and corrosion wear in SBF solution. ► The ESA layer prepared in silicone oil using a graphite electrode indicates good biocompatibility, and rough surface can help to enhance early cell attachment capacity.In order to improve the biomedical properties of a titanium alloy surface, electro-spark surface alloying was carried out using a graphite electrode in air, in a nitrogen gas atmosphere and in silicone oil. The morphology and microstructure of the strengthened layers were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The hardness distributions as a function of depth were measured by a micro-hardness tester. Corrosion resistance capacities of the modified layers were evaluated using potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS). In addition, wear resistance and corrosive wear properties in a simulated body fluid (SBF) were studied with a pin-on-disk tribometer. Alloyed layers, completely covering the substrate surface and about 40μm thick mainly composed of the TiC phase and with strong metallurgical bonding and adhesion to the substrate, were obtained. This can markedly improve hardness and wear resistance of the surface layer of the substrate. In comparison to coatings prepared in air and nitrogen gas atmospheres, the coating produced in silicone oil media exhibits a denser and more perfect surface structure. The wear resistance in air and corrosive wear resistance in SBF solution is the best for the coating produced in silicone oil. For instance, the wear rate in air with a GCr15 steel ball counterpart is reduced by a factor of 29 compared with the original titanium alloy and the corrosive wear rate in SBF solution with a corundum ball can decrease by a factor of 13.8. Simultaneously, the effect of electron-spark surface alloying of the titanium alloy surface on biocompatibility and biological activity was also investigated. The electron-spark surface strengthened layer treated in silicone oil shows good biocompatibility and biological activity, and can help cell attachment to the substrate surface.

Keywords: Electro-spark alloying (ESA); Titanium alloy; Wear; Corrosive wear; Biocompatibility; Biological activity

Surface energies of metals in both liquid and solid states by Fathi Aqra; Ahmed Ayyad (pp. 6372-6379).

Display Omitted► Models are proposed for surface energies calculations of metals. ► Results agree well with reported data. ► Fraction of broken bonds in metals is determined. ► We provide useful data for engineers and science community.Although during the last years one has seen a number of systematic studies of the surface energies of metals, the aim and the scientific meaning of this research is to establish a simple and a straightforward theoretical model to calculate accurately the mechanical and the thermodynamic properties of metal surfaces due to their important application in materials processes and in the understanding of a wide range of surface phenomena. Through extensive theoretical calculations of the surface tension of most of the liquid metals, we found that the fraction of broken bonds in liquid metals ( f) is constant which is equal to 0.287. Using our estimated f value, the surface tension ( γ_m), surface energy ( γ_SV), surface excess entropy (−d γ/d T), surface excess enthalpy ( H_s), coefficient of thermal expansion ( α_m and α_b), sound velocity ( c_m) and its temperature coefficient (−d c/d T) have been calculated for more than sixty metals. The results of the calculated quantities agree well with available experimental data.

Keywords: Surface energies; Liquid metals; Modeling

Effect of annealing temperature on microstructure, hardness and adhesion properties of TiSi_xN_y superhard coatings by Y.H. Lu; J.P. Wang; S.L. Tao; Z.F. Zhou (pp. 6380-6386).

► In this study, effect of annealing temperature on film-matrices adhesive strength was focused. ► The results indicate that annealing treatment below 900°C played a little role in microstructure, hardness and friction coefficient; however it greatly affected those of steel substrates. ► The hardness and grain size of steel substrates greatly decreased after 600°C. ► With increase of annealing temperature the film-matrices adhesive strength was slightly increased up to 600°C, followed by an abrupt decrease with further increasing annealing temperature. Its maximum was gotten at 600°C.A series of TiSi_xN_y superhard coatings with different Si contents were prepared on M42 steel substrates using two Ti and two Si targets by reactive magnetron sputtering at 500°C. These samples were subsequently vacuum-annealed at 500, 600, 700, 800 and 900°C, respectively. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), microindenter, Rockwell hardness tester and scratch tester were applied to investigate the microstructure, phase configuration, hardness and adhesion properties of as-deposited and annealed samples. The results indicated that there were two bonds, TiN and Si₃N₄, in all presently deposited TiSi_xN_y thin films, that structure was nanocomposite of nanocrystalline (nc-) TiN embedded into amorphous Si₃N₄ matrices. Annealing treatment below 900°C played a little role in microstructure and hardness of the coatings although it greatly affected those of steel substrates. The film-substrate adhesion strength was slightly increased, followed by an abrupt decrease with increasing annealing temperature. Its value got to the maximum at 600°C. Annealing had little effect on the friction coefficient with its value varying in the range of 0.39–0.40.

Keywords: TiSi; _x; N; _y; Nanocomposite; Annealing treatment; Microstructure; Adhesion

Influence of the nitrogen contents on the permeability characteristics and soft magnetic properties of FeHfN films by Yu-Ming Kuo; Jenq-Gong Duh (pp. 6387-6390).

► Nanocrystalline FeHfN thin films can be fabricated by dc reactive magnetron sputtering. ► Appropriate nitrogen flow rate enables the formation of Nanocrystalline. ► The microstructure shows strong effect on magnetic properties. ► The FeHfN thin films with superior soft magnetic properties are obtained when the N₂ flow is 1.2sccm.High permeability magnetic films can enhance the inductance of thin-film inductors in DC–DC converters. In order to obtain high permeability, the uniaxial anisotropy and coercivity should be as low as possible. This study employed dc reactive magnetron sputtering to fabricate nanocrystalline FeHfN thin films. The influence of the nitrogen flow on the composition, microstructure, and permeability characteristics, as well as magnetic properties was investigated. Increasing the nitrogen content can alter FeHfN films from amorphous-like to crystalline phases. The magnetic properties and permeability depend on variations in the microstructure. With the optimum N₂/Ar flow ratio of 4.8% (N₂ flow: 1.2sccm), low anisotropy ( H_K=18Oe), low coercivity ( H_C=1.1Oe) and high permeability ( μ′>600 at 50MHz) were obtained for fabrication of a nanocrystalline FeHfN film with a thickness of around 700nm. Such as-fabricated FeHfN films with a permeability of over 600 should be a promising candidate for high-permeability ferromagnetic material applications.

Keywords: Coercivity; Anisotropy; Microstructure; Permeability

High-temperature pretreatment of Ni nanoparticles enhances the growth of high-density carbon fiber bundles during microwave plasma chemical vapor deposition by Derming Lian; Chien-Huang Tsai (pp. 6391-6396).

► We evaluated the pretreatment procedure of Ni nanoparticles (NPs) on the growth of multiwalled carbon nanotube (MWCNT) bundles by means of microwave plasma chemical vapor deposition (MPCVD). ► The diameter and shape of the Ni NPs were the dominant factors affecting the size and density of the MWCNT bundles. ► We obtained MWCNTs that fully filled the via effectively; they might serve as potential interconnects in future nanodevices.This paper presents an experimental study on the effect of the pretreatment procedure of Ni nanoparticles (NPs) on the growth of multiwalled carbon fiber (CNF) bundles by means of microwave plasma chemical vapor deposition (MPCVD). We used atomic force microscopy to investigate a series of pretreated Ni films. The structures and compositions of the CNFs on the via were investigated using scanning electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy.The geometric shape of the Ni NPs was identified in terms of their roughness, which decreased upon increasing the pretreatment temperature, resulting subsequently in the synthesis of high-density CNFs. The diameter and shape of the Ni NPs were the dominant factors affecting the size and density of the CNFs bundles. We obtained CNFs that fully filled the via effectively; they might serve as potential interconnects in future nanodevices.

Keywords: Chemical vapor deposition; High-resolution transmission electron microscopy; Scanning electron microscopy; Atomic force microscopy

Surface characterization of anodized zirconium for biomedical applications by A. Gomez Sanchez; W. Schreiner; G. Duffó; S. Ceré (pp. 6397-6405).

► Systematic surface characterization on electrochemically grown oxides at low potentials on Zr. ► Anodized zirconium used for biomedical applications. ► Surface modification as a route to enhance biocompatibility of permanent implants.Mechanical properties and corrosion resistance of zirconium make this material suitable for biomedical implants. Its good in vivo performance is mainly due to the presence of a protective oxide layer that minimizes corrosion rate, diminishes the amount of metallic ions released to the biological media and facilitates the osseointegration process.Since the implant surface is the region in contact with living tissues, the characteristics of the surface film are of great interest. Surface modification is a route to enhance both biocompatibility and corrosion resistance of permanent implant materials. Anodizing is presented as an interesting process to modify metal surfaces with good reproducibility and independence of the geometry.In this work the surface of zirconium before and after anodizing in 1mol/L phosphoric acid solution at a fixed potential between 3 and 30V, was characterized by means of several surface techniques.It was found that during anodization the surface oxide grows with an inhomogeneous coverage on zirconium surface, modifying the topography. The incorporation of P from the electrolyte to the surface oxide during the anodizing process changes the surface chemistry. After 30 days of immersion in Simulated Body Fluid (SBF) solution, Ca-P rich compounds were present on anodized zirconium.

Keywords: Key words; Zirconium; Permanent implants; Surface film

The enhanced photocatalytic activity of CdS/TiO₂ nanocomposites by controlling CdS dispersion on TiO₂ nanotubes by Shuli Bai; Huanying Li; Yujiang Guan; Shengtao Jiang (pp. 6406-6409).

► CdS/TiO₂ catalysts were prepared via a simple wet chemical method. ► The prepared CdS/TiO₂ catalysts possess high visible light photocatalytic activity. ► The photocatalytic activity depends on the dispersion of CdS nanoparticles.CdS/TiO₂ nanocomposites were prepared via a simple wet chemical method, and characterized through X-ray diffraction (XRD) and transmission electron microscopy (TEM). Their ability to degrade Acid Rhodamine B was investigated under visible light irradiation. The results indicate that CdS/TiO₂ nanocomposite with a mass ratio of 4:1(TiO₂:CdS) showed high photocatalytic activity and the CdS loaded on TiO₂ nanotube surface exhibited a hexagonal phase. The dispersion of CdS on TiO₂ nanotube surface had an important effect on the degradation efficiency of pollutant, which provides a strategy for practical industry application.

Keywords: TiO; ₂; nanotubes; CdS; Photocatalytic activity

DFT study of structural, electronic and vibrational properties of pure (Al₂O₃)_n ( n=9, 10, 12, 15) and Ni-doped (Al₂O₃)_n ( n=9, 10) clusters by Xiaozhen Zheng; Yonghong Zhang; Shiping Huang; Hui Liu; Peng Wang; Huiping Tian (pp. 6410-6417).

Geometry optimized structures of Ni-doped (Al₂O₃)₉ clusters. Al, O and Ni atoms are represent by purple, red and blue, respectively.Display Omitted► We investigate the geometrical structures and stability of Ni-doped (Al₂O₃)_n ( n=9, 10) clusters. ► The impurity of nickel atom is mainly responsible for the reduction of the energy gap. ► The vibrational band at 1030cm⁻¹ is ascribed to the asymmetric Al–O–Al stretching vibration.The geometrical, electronic and vibrational properties of pure (Al₂O₃)_n ( n=9, 10, 12, 15) clusters and Ni-doped (Al₂O₃)_9–10 clusters are investigated by density functional theory. There are four different Ni-doped (Al₂O₃)₉ clusters and one Ni-doped (Al₂O₃)₁₀ cluster taken into account. Compared with the pure clusters, the Ni-doped (Al₂O₃)_9–10 clusters have narrower HOMO–LUMO energy gaps. The results indicate that the impurity of Ni atom is mainly responsible for the reduction of the HOMO–LUMO energy gap. One characteristic vibration band at about 1030cm⁻¹ is found in the vibrational frequencies of the Ni-doped (Al₂O₃)_9–10 clusters, which is caused by the asymmetric Al–O–Al stretching vibration. Another band at around 826cm⁻¹ involving the characteristic vibration of Ni–O bond is in good agreement with experimental results.

Keywords: Density functional theory; Alumina clusters; Ni-doped alumina clusters; Electronic properties; Vibrational frequencies

Effect of heat treatment on the properties of dc magnetron sputtered LaB₆/ITO films by Dan Wang; Lin Zhang; Guanghui Min; Huashun Yu; Yifei Yuan (pp. 6418-6423).

.Display Omitted► LaB₆/ITO films were deposited by direct current magnetron sputtering method. ► Their resistivity declined over one order of magnitude after heat treatment. ► The best photoelectric capability was gained at Ar pressure of 2.5Pa. ► The films’ cross-sections changed from strongly columnar to the equiaxial.Two types of LaB₆/ITO films with different deposition times were deposited by direct current magnetron sputtering. After the films were fabricated, AFM, XRD, FESEM, Step-Height Profiler, UV–Vis Spectrophotometer and Hall Measurement Instrument were used to study their performances. After 400°C's annealing, morphology of fracture cross-sections of the films exhibit evolutions from strongly columnar to the equiaxial (30min), the films prepared with short time transformed from amorphous to polycrystalline, and Ar pressure generated little effect on the film's transmissivity. The resistivity declined over one order of magnitude, and the films with higher surface roughness value were more resistant, while that for films unheatreated was just the opposite.

Keywords: LaB; ₆; ITO; Heat treatment; Direct current magnetron sputtering

Chemical effects during ripple formation with isobaric ion beams by S. Sarkar; A. Franquet; A. Moussa; W. Vandervorst (pp. 6424-6428).

The formation of nanostructures on SiGe surfaces by erosion using mixed beams of isobaric species (Cs/Xe) is shown to depend on the Cs/Xe ratio. The nanostructures exhibit different wavelengths (longer wavelengths for higher Cs concentrations) contrary to the present theoretical understanding. Moreover, experiments with pure Cs and Xe beams also demonstrate that such differences are enhanced at lower bombarding energies. Such effects are primarily due to the fact that the retentivity and mobility of cesium at the sample surface gets enhanced at lower bombarding energies. The phenomenon could be explained theoretically by including an additional diffusion term in the growth equation describing the mobility of the primary ions on the irradiated surface. Semi-empirical calculations done in this direction also confirm this phenomenon.

Keywords: Nanopatterning; Sputtering; Atomic force microscopy

The cytocompatibility investigation of Ti6Al4V modified with a fluorine-contained copolymer thin film by Yijun Liu; Jia Luo; Bin Liu; Junyan Zhang (pp. 6429-6434).

► A stable fluorine-contained copolymer thin film was prepared on Ti₆Al₄V surfaces. ► This film provided long-term protection for substrates in simulated body fluid. ► The film could promoted the proliferation of osteoblasts. ► The film has potential applications in the biomedical field.The objective of the present study is to preliminarily explore the effect of surface chemistry modification of Ti6Al4V with a fluorine-contained copolymer thin film on the cellular behavior of osteoblasts. A fluorine-contained random copolymer thin film was fabricated on Ti6Al4V substrate, and then characterized by X-ray photoelectron spectroscopy (XPS), contact angle meter and surface profiler. The results showed that the surface modification of Ti6Al4V alloy could simultaneously transform the surface chemical constitution and reduce the surface energy evidently. However, the surface morphology and roughness of the Ti6Al4V substrate were hardly changed after the modification. By immersion process with simulated body fluid (SBF) and then by in vitro cytotoxicity test with MC3T3-E1 osteoblasts, the fluorine-contained copolymer thin film exhibited desirable stability and admirable cytocompatibility. In conclusion, the fluorine-contained copolymer thin film could be easily applied in modifying various solid surfaces, and the as-fabricated film also has potential applications in biomedical field.

Keywords: Copolymer; Thin film; Ti6Al4V; Cytocompatibility; Osteoblast

Layer-by-layer deposition of Ti–4,4′-oxydianiline hybrid thin films by Anjali Sood; Pia Sundberg; Jari Malm; Maarit Karppinen (pp. 6435-6439).

► A novel inorganic–organic hybrid material of the (–Ti–N–C₆H₄–O–C₆H₄–N–)_n type is reported. ► The new hybrid material is grown layer-by-layer with an ALD-type process. ► Hybrid films deposited at 250–490°C are stable in atmospheric conditions. ► Films grown at higher temperatures are more stable than those grown at lower temperatures. ► The growth rate increases with increasing temperature.Features of the two thin-film techniques, atomic layer deposition (ALD) and molecular layer deposition (MLD), are combined to build up a stable novel inorganic–organic hybrid material of the (–Ti–N–C₆H₄–O–C₆H₄–N–)_n type, deposited from successive pulses of TiCl₄ and 4,4′-oxydianiline precursors. Depositions in the temperature range of 160–230°C resulted in unstable films, while the films obtained in the temperature range of 250–490°C were found stable in atmospheric air. The growth rate increased with increasing temperature, from 0.3Å per cycle at 160°C to 1.1Å per cycle at 490°C.

Keywords: Inorganic–organic hybrid; Atomic layer deposition; Molecular layer deposition

Energy gap modulation of graphene nanoribbons by F termination by Dao-bang Lu; Yu-ling Song; Zong-xian Yang; Gen-quan Li (pp. 6440-6444).

► The electronic properties of graphene nanoribbons are studied for the F-terminated instead of the H-terminated by using the first-principles. ► F-terminated armchair graphene nanoribbons have lower band gaps than those of H-terminated ones when they have the same band width. ► C–F bond is an ionic bond, while, C–C bond displays a typical non-polar covalent bonding feature.Under the generalized gradient approximation (GGA), the electronic properties are studied for the F-terminated graphene nanoribbons (GNRs) with either zigzag edge (ZGNRs) or armchair edge (AGNRs) by using the first-principles projector augmented wave potential within the density function theory (DFT) framework. The results show that an edge state appears at the Fermi level E_F in the broader F-terminated ZGNRs, but does not appear in all the F-terminated AGNRs due to their dimerized C–C bonds at edge. The density of states (DOS) and projected DOS (PDOS) analyses show that the F-terminated ZGNRs are metallic and have a sharp peak at the Fermi level when the width is large enough. In contrast, the AGNRs are always semiconductors independent of their width. The charge density contours analyses shows that the C–F bond is an ionic bond due to a much stronger electronegativity of the F atom than that of the C atom. However, all kinds of the C–C bonds display a typical nonpolar covalent bonding feature.

Keywords: First principle; Electronic property; Band structure; F termination; GNRs

Pulsed laser deposition and characterization of multilayer metal-carbon thin films by K. Siraj; M. Khaleeq-ur-Rahman; M.S. Rafique; M.Z. Munawar; S. Naseem; S. Riaz (pp. 6445-6450).

► Co-DLC multilayer thin films have been deposited by PLD. ► Co-particles of different sizes are embedded in DLC matrix. ► Raman spectra contain characteristics D- and G-bands of DLC films. ► VSM analysis reveals Co–C multilayer films show ferromagnetic behaviour. ► Optical band gaps of DLC films can be tuned by varying Co-content.Cobalt-DLC multilayer films were deposited with increasing content of cobalt, keeping carbon content constant by pulsed laser deposition technique. A cobalt free carbon film was also deposited for comparison. Excimer laser was employed to ablate the materials onto silicon substrate, kept at 250°C, while post-deposition annealing at 400°C was also performed in situ. The formation of cobalt grains within the carbon matrix in Co-DLC films can be seen through scanning electron and atomic force micrographs while no grains on the surface of the cobalt-free DLC film were observed. Raman spectra of all the films show D- and G-bands, which is a confirmation that the films are DLC in nature. According to Vibrating sample magnetometer (VSM) measurements, the DLC films with cobalt revealed ferromagnetic behaviour whereas the cobalt free DLC film exhibited diamagnetic behaviour. The pure DLC film also shows ferromagnetic nature when diamagnetic background is subtracted. Spectroscopic Ellipsometry (SE) analysis showed that the optical band gaps, refractive indices and extinction coefficients of Co-DLC films can be effectively tuned with increasing content of cobalt.

Keywords: PACS; 75.70.Cn; 78.20.Ci; 81.15.FgPulsed laser deposition; DLC's; Optical properties; Magnetic properties

Effect of heat treatment on morphology, crystalline structure and photocatalysis properties of TiO₂ nanotubes on Ti substrate and freestanding membrane by Dong Fang; Zhiping Luo; Kelong Huang; Dimitris C. Lagoudas (pp. 6451-6461).

► TiO₂ nanotubes are fabricated in a glycol solution by anodization. ► We examine morphology and crystalline changes of TiO₂ nanotubes during annealing. ► The TiO₂ nanotubes with or without the Ti substrate have different properties on morphology and crystalline changes. ► Models to explain the changes of TiO₂ nanotubes are presented. ► Photocatalytic activity is examined for the TiO₂ nanotubes on the Ti substrate.Highly ordered titanium oxide (TiO₂) nanotubes were prepared by electrolytic anodization of titanium electrodes. Morphological evolution and phase transformations of TiO₂ nanotubes on a Ti substrate and that of freestanding TiO₂ membranes during the calcinations process were studied by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction microscopy. The detailed results and mechanisms on the morphology and crystalline structure were presented. Our results show that a compact layer exists between the tubular layer and Ti substrate at 600°C, and the length of the nanotubes shortens dramatically at 750°C. The freestanding membranes have many particles on their tubes during calcinations from 450 to 900°C. The TiO₂ nanotubes on the Ti substrate transform to rutile crystals at 600°C, while the freestanding TiO₂ membranes retain an anatase crystal with increasing temperature to 800°C. The photocatalytic activity of TiO₂ nanotubes on a Ti substrate annealed at different temperatures was investigated by the degradation of methyl orange in aqueous solution under UV light irradiation. Due to the anatase crystals in the tubular layer and rutile crystals in the compact layer, TiO₂ nanotubes annealed at 450°C with pure anatase crystals have a better photocatalytic activity than those annealed at 600°C or 750°C.

Keywords: TiO; ₂; nanotube arrays; Anodic oxidation; Calcination; Phase transformation; Photocatalysis

Adsorption of water on TiN (100), (110) and (111) surfaces: A first-principles study by Suchismita Sanyal; Umesh V. Waghmare; James A. Ruud (pp. 6462-6467).

Display Omitted► We study dependence of adsorption of H₂O at TiN on its surface orientation. ► H₂O adsorbs molecularly on TiN (100) and (111) surfaces with energies −0.94 and −0.78eV respectively. ► H₂O adsorbs dissociatively on TiN (110) surface with stronger binding (−2.44eV). ► General trends seen above explain H₂O adsorption on other surfaces (e.g. ZrN/MgO).We use first-principles density functional theory-based calculations in the analysis of the interaction of H₂O with (100), (110) and (111) surfaces of TiN, and develop understanding in terms of surface energies, polarity of the surface and chemistry of the cation, through comparison with H₂O adsorption on ZrN. While water molecule physisorbs preferentially at Ti site of (100) and (111) surfaces, it adsorbs dissociatively on (110) surface of TiN with binding stronger than almost 1.32eV/molecule. Our analysis reveals the following general trends: (a) surfaces with higher energies typically lead to stronger adsorption, (b) dissociative adsorption of H₂O necessarily occurs on a charge neutral high energy surface and (c) lower symmetry of the (110) plane results in many configurations of comparable stability, as opposed to the higher symmetry (100) and (111) surfaces, which also consistently explain the results of H₂O adsorption on MgO available in literature. Finally, weaker adsorption of H₂O on TiN than on ZrN can be rationalized in terms of greater chemical stability of Ti arising from its ability to be in mixed valence.

Keywords: Density functional theory; TiN; Adsorption energy; Coating

The formation model of Ni–Cr oxides on NiCoCrAlY-sprayed coating by G.Y. Liang; C. Zhu; X.Y. Wu; Y. Wu (pp. 6468-6473).

► We studied the oxidation behaviour of the NiCoCrAlY-sprayed coating at 1000°C. ► The study was carried out from both the experimental and crystal point of view. ► The atomic arrangement and distribution of oxides were analyzed. ► The formation model of oxides is based on the matching relationship between atoms.The atomic arrangement and distribution of oxides (Cr₂O₃, NiCr₂O₄ and NiO) on the sprayed-NiCoCrAlY coating after oxidation are analyzed. The formation and the growth model of Ni–Cr oxide phases are discussed according to the matching relationship between atoms. The outline character and a scale of spinel NiCr₂O₄ are discussed. The results show that Cr atoms can form two close-packed arrangements in the crystal plane of Cr₂O₃ perpendicular to 〈001〉 orientation. The atomic spacing in the first arrangement corresponds to double that of Ni/Ni₃Al in {111} crystal face. This suggests that Ni/Ni₃Al is the substrate for Cr₂O₃ to grow along 〈001〉 direction. The lattice mismatch between Cr₂O₃ and Ni/Ni₃Al is less than that of Al₂O₃, which indicates that Cr₂O₃ is easier to form than Al₂O₃ during the oxidation process. The atomic spacing in another close-packed arrangement of Cr₂O₃ perpendicular to 〈001〉 orientation is approximately equal to that of Ni or Cr in the plane of NiCr₂O₄ and NiO perpendicular to 〈111〉 orientation. So Cr₂O₃ can be the substrate for NiCr₂O₄ and NiO to grow in the 〈001〉 direction. NiCr₂O₄ and NiO can grow directly along the 〈111〉 orientation on each other. NiCr₂O₄ can grow outward in the planes of Cr₂O₃ perpendicular to 〈001〉 and grow inward along 〈111〉 orientation of NiO.

Keywords: Oxides; Close-packed arrangement; Atomic spacing; Growth orientation

Characterization of chemically deposited ZnSe/SnO₂/glass films: Influence of annealing in Ar atmosphere on physical properties by H. Metin; S. Durmuş; S. Erat; M. Ari (pp. 6474-6480).

► In our work, some of the films were annealed in Ar atmosphere at different temperature in order to investigate the annealing effects on structural, optical, and electrical properties of the films. ► The complete phase transformation from cubic to hexagonal does not observed. ► We showed the annealing effects on structural parameters such as crystallite size, dislocation density, and strain. ► Optical band gap energy and activation energy of the films were calculated and the variation of these energies with annealing temperature is well described in the manuscript.The Zinc Selenide (ZnSe) thin films have been deposited on SnO₂/glass substrates by a simple and inexpensive chemical bath deposition (CBD). The structural, optical and electrical properties of ZnSe films have been characterized by X-ray diffraction (XRD), Energy Dispersive X-ray Analysis (EDAX), optical absorption spectroscopy, and four point probe techniques, respectively. The films have been subjected to different annealing temperature in Argon (Ar) atmosphere. An increase in annealing temperature does not cause a complete phase transformation whereas it affects the crystallite size, dislocation density and strain. The optical band gap ( E_g) of the as-deposited film is estimated to be 3.08eV and decreases with increasing annealing temperature down to 2.43eV at 773K. The as-deposited and annealed films show typical semiconducting behaviour, d ρ/d T>0. Interestingly, the films annealed at 373K, 473K, and 573K show two distinct temperature dependent regions of electrical resistivity; exponential region at high temperature, linear region at low temperature. The temperature at which the transition takes place from exponential to linear region strongly depends on the annealing temperature.

Keywords: ZnSe; SnO; ₂; Optical properties; Electrical properties

Oxidation kinetics of thin copper films and wetting behaviour of copper and Organic Solderability Preservatives (OSP) with lead-free solder by Mauricio Ramirez; Lothar Henneken; Sannakaisa Virtanen (pp. 6481-6488).

► A correlation between Cu oxide thickness and wetting angle was established. ► It was found that the wetting is acceptable only when the Cu oxides are under 16nm. ► Surfaces coated with Organic Solderability Preservatives (OSP) were also studied. ► Oxidation of surfaces coated with OSP takes place under the organic layer. ► The determined activation energy for the OSP thermal decomposition is 32.6kJ/mol.The oxide formation on thin copper films deposited on Si wafer was studied by XPS, SEM and Sequential Electrochemical Reduction Analysis SERA. The surfaces were oxidized in air with a reflow oven as used in electronic assembly at temperatures of 100°C, 155°C, 200°C, 230°C and 260°C. The SERA analyses detected only the formation of Cu₂O but the XPS analysis done for the calibration of the SERA equipment proved also the presence of a CuO layer smaller than 2nm above the Cu₂O oxide. The oxide growth follows a power-law dependence on time within this temperature range and an activation energy of 33.1kJ/mol was obtained. The wettability of these surfaces was also determined by measuring the contact angle between solder and copper substrate after the soldering process. A correlation between oxide thickness and wetting angle was established. It was found that the wetting is acceptable only when the oxide thickness is smaller than 16nm. An activation energy of 27kJ/mol was acquired for the spreading of lead free solder on oxidized copper surfaces.From wetting tests on copper surfaces protected by Organic Solderability Preservatives (OSP), it was possible to calculate the activation energy for the thermal decomposition of these protective layers.

Keywords: Copper oxidation; Soldering; OSP; Lead-free; Final finish; XPS

Wettability behaviour of RTV silicone rubber coated on nanostructured aluminium surface by Gelareh Momen; Masoud Farzaneh; Reza Jafari (pp. 6489-6493).

► A superhydrophobic surface was prepared via aluminium anodisation followed by silicone rubber coating. The anodisation voltage affects the size and form of the pore. ► An important delayed freezing time on the superhydrophobic surfaces was observed. Wettability behaviour of superhydrophobic surface depends strongly on substrate temperature. Increasing the anodising voltage reduced the capacitance of superhydrophobic surfaces.A nanostructutered superhydrophobic surface was elaborated by applying an RTV silicone rubber coating on electrochemically processed aluminium substrates. Study of anodisation voltage on surface morphology showed that higher anodising voltage led to larger pore sizes. Scanning electron microscopy image analysis showed bird's nest and beehive structures formed on anodised surfaces at 50V and 80V. Water static contact angle on the treated surfaces reached up to 160° at room temperature. Study of superhydrophobic surfaces at super cooled temperature showed important delayed freezing time for RTV hydrophobic surfaces when compared to non-treated aluminium. However, lower wettability was observed when surface temperature went down from 20°C to −10°C. Also, it was found that the capacitance of superhydrophobic surfaces decreased with increasing anodising voltage.

Keywords: Superhydrophobicity; Anodising; Supercooled temperature; Silicone rubber; Voltage

Preparation of carbon supported Pt–P catalysts and its electrocatalytic performance for oxygen reduction by Juan Ma; Yawen Tang; Gaixiu Yang; Yu Chen; Qun Zhou; Tianhong Lu; Junwei Zheng (pp. 6494-6497).

► The carbon supported PtP (PtP/C) catalysts were synthesized from Pt(NO₃)₂ and phosphorus yellow at the room temperature. ► The content of P in the PtP/C catalysts prepared with this method is high and the average size of the PtP particles is decreased with increasing the content of P. ► The electrocatalytic performances of the PtP/C catalysts prepared with this method for the oxygen reduction reaction (ORR) are better than that of the commercial Pt/C catalyst.The carbon supported PtP (PtP/C) catalysts were synthesized from Pt(NO₃)₂ and phosphorus yellow at the room temperature. The content of P in the PtP/C catalysts prepared with this method is high and the average size of the PtP particles is decreased with increasing the content of P. The electrocatalytic performances of the PtP/C catalysts prepared with this method for the oxygen reduction reaction (ORR) are better than that of the commercial Pt/C catalyst. The promotion action of P for enhancing the electrocatalytic performance of the PtP/C catalyst for ORR is mainly due to that Pt and P form the alloy and then the electron density of Pt is decreased.

Keywords: Preparation method of catalyst; Carbon supported PtP catalyst; Phosphorus yellow; Oxygen reduction reaction

Influence of the grain boundary barrier height on the electrical properties of Gallium doped ZnO thin films by Chang-Feng Yu; Sy-Hann Chen; Shih-Jye Sun; Hsiung Chou (pp. 6498-6502).

► GZO thin films were deposited by PLD with the various Ga doping. ► The carrier concentration and oxygen vacancies in the GZO thin films increased with an increase of Ga doping. ► The 3.0% Ga doped thin film exhibited the lowest resistivity as low as 3.63×10⁻⁴Ωcm. ► The lower barrier height of grain boundaries would cause the lower resistivity.The pulsed laser deposition (PLD) technique is used to deposit Gallium doped zinc oxide (GZO) thin films on glass substrates at 250 with different Gallium (Ga) doping concentration of 0, 1.0, 3.0 and 5.0%. The influence of Ga doping concentration on structure, chemical atomic compositions, electrical and optical properties was investigated by XRD, XPS, Hall measurement and UV spectrophotometer, respectively. The relationship between electrical properties and Ga doping concentration was clarified by analyzing the chemical element compositions and the chemical states on the GZO films. It is found that the carrier concentrations and oxygen vacancies in the GZO films increase with increasing Ga doping concentration. The lowest resistivity (3.63×10⁻⁴Ωcm) and barrier height of grain boundaries (14mV) were obtained with 3% Ga doping. In particular, we suppose the band gap of 5% Ga doping sample larger than that of 3% Ga doping sample is due to the quantum size effect from the amorphous structure rather than Moss–Burstein shift.

Keywords: Pulsed laser deposition; Gallium doped zinc oxide; Quantum size effect; Barrier height

Dynamic modeling of manipulation of micro/nanoparticles on rough surfaces by M.H. Korayem; M. Zakeri (pp. 6503-6513).

► The nanoparticle pushing on the rough substrates are studied based on AFM. ► The contact attributes by combination of the JKR, Schwarz, and Rumpf/Rabinovich theories are derived. ► The dynamic behavior of particle change on rough surface; and the force decreases. ► The critical values are more sensitive to the asperity radius than the height. ► The force decreases by the increment of the asperity radius within the range of 0.5< r<5nm.In this paper, the dynamic behavior of spherical micro/nanoparticles, while being pushed on rough substrates, is studied by means of an Atomic Force Microscope (AFM). For this purpose, first, the contact adhesion force, and the areas and penetration depths of rough surfaces are derived based on the Johnson–Kendall–Roberts (JKR) theory, the Schwarz method, and the Rumpf/Rabinovich models. Then, the dynamic model of particle manipulation on rough substrates is revised using the specified contact theory for rough surfaces. And finally, the pushing of spherical particles with 50, 100, 200, 500, and 10000nm radii is simulated. The results show that the critical force and the critical time of manipulation decrease when the particles are pushed on the rough surfaces as compared to the smooth ones. It is also observed that the critical force for a rough substrate containing asperities of low height and large radius approaches a comparable critical force magnitude to the smooth substrate, as is expected. Also, when the asperity radius in the substrate is within the range of 0.5< r<5nm, the critical force of pushing decreases; however, as the asperity radius becomes larger than 5nm, the critical force begins to increase again. Furthermore, the critical values are generally more sensitive to the changes of the asperity radius than the height. It is also found that the difference between the critical values based on the Rumpf and Rabinovich models is negligible. However, the estimation of particles’ dynamic behavior using the Rumpf model could be wrong for the rough substrates with small radius asperities, which is considerable in the manipulation and assembly practices. Moreover, the dynamic behavior of particles of small radius ( r<500nm) change during the pushing process on rough surfaces, and the rolling behavior could be possible on the surfaces that have small radius asperities. The probability of this occurrence is increased in the pushing of larger particles on rougher substrates.

Keywords: AFM; Dynamics; Modeling; Manipulation; Nanoparticles; Roughness

Single-molecule conductance measurement of self-assembled organic monolayers using scanning tunneling spectroscopy in combination with statistics analysis by Yumei Zhang; Chengfu Dou; Yin Wang (pp. 6514-6517).

► Compared with CP-AFM technique, STS technique avoids the coulomb blockade effect from contact resistance between the tip and molecules due to the tip is away from the molecules. ► The solvent effect on the conductance was removed since the procedure was performed on ambient rather than the dilute solution. ► The conductance of either mono- or bi- functional molecule may be measured, compared with only bifunctional molecules for break junction approach due to the attachment of molecule between two electrodes.Based on ambient atmosphere scanning tunneling microscope (STM) technique, scanning tunneling spectroscopy (STS) combined with statistics analysis was developed to investigate the single-molecule conductance of various kinds of molecules which were self-assembled on the Au (111). Conductance histograms obtained from current–voltage curves revealed well-defined peaks at integer multiples of a fundamental conductance and were used to identify the conductance of a single molecule. The conductances of saturated molecules like 1,8-octanedithol and hexanethiocyanate were found to be 0.072×10⁻⁴G₀ and 0.06×10⁻⁴G₀ respectively and 0.23×10⁻⁴G₀ and 0.13×10⁻⁴G₀ for unsaturated molecules like 5,5′-dithiol- 2,2′,5′,2″-terthiophene and 4,4′-dithio-tert(phenylene ethylene).

Keywords: Self-assembled; Single-molecule conductance; STS

Experimental determination of solid–liquid interfacial energy for solid Sn in the Sn–Mg system by Fatma Meydaneri; Buket Saatçi; Mehmet Özdemir (pp. 6518-6526).

► The interface energy plays a key role in nucleation, phase transformations etc. ► GBG shapes for solid Sn in equilibrium with Sn–Mg eutectic liquid were observed. ► The thermal conductivity of the Sn–9at.% Mg solid phase, κ_S has been measured. ► R of eutectic liquid phase to the eutectic solid phase has been determined. ► Γ, σ_SL and σ_GB from the observed grain boundary groove shapes were determined. ► Γ, σ_SL, σ_GB have been found to be 7.35±0.36×10⁻⁸Km, 136.41±13.64 and 230.95±25.40mJm⁻².The equilibrated grain boundary groove shapes for solid Sn in equilibrium with the Sn–9at.% Mg eutectic liquid were directly observed annealing a sample at the eutectic temperature for about 5 days with a radial heat flow apparatus. The thermal conductivities of the solid phase, κ_S, and the liquid phase, κ_L, for the groove shapes were measured. From the observed grain boundary groove shapes, the Gibbs–Thomson coefficient, the solid–liquid interfacial energy and grain boundary energy for solid Sn in equilibrium with the Sn–9at.% Mg eutectic liquid have been determined to be (7.35±0.36)×10⁻⁸Km, (136.41±13.64)×10⁻³Jm⁻² and (230.95±25.40)×10⁻³Jm⁻², respectively.

Keywords: Sn–Mg alloy; Gibbs–Thomson coefficient; Interface energy; Grain boundary energy

Synthesis of urchin-like Co₃O₄ hierarchical micro/nanostructures and their photocatalytic activity by Hui Li; Guang Tao Fei; Ming Fang; Ping Cui; Xiao Guo; Peng Yan; Li De Zhang (pp. 6527-6530).

Display Omitted► Urchin-like Co₃O₄ hierarchical micro/nanostructures as catalyst. ► Catalyst shows high degradation efficiency and stability for reactive black dyes. ► Large porosity and small particles size is favored in the degradation process.Urchin-like Co₃O₄ hierarchical micro/nanostructures have been successfully synthesized by calcining urchin-like precursor CoCO₃, which are prepared by a facile hydrothermal route. The particle size of the urchin-like Co₃O₄ could be easily controlled by altering the calcination temperature. The morphology and structure of the as-prepared urchin-like products were characterized by XRD, FESEM and TEM. Photocatalytic measurement demonstrates that these urchin-like Co₃O₄ micro/nanostructures show good photocatalytic effect and their degradation efficiency is strongly dependent on their particle size. Furthermore, a plausible reaction mechanism is also proposed to illustrate the photocatalytic processes of Co₃O₄.

Keywords: Co; ₃; O; ₄; Urchin-like structure; Hydrothermal; Photocatalytic; Particle size

Relatively low temperature synthesis of graphene by radio frequency plasma enhanced chemical vapor deposition by J.L. Qi; W.T. Zheng; X.H. Zheng; X. Wang; H.W. Tian (pp. 6531-6534).

► We have successfully synthesized high-quality, large-area graphene using RF-PECVD technique at substrate temperature as relatively low as 650°C on SiO₂/Si substrate covered with Ni thin film. ► During deposition, the trace amount of carbon (CH₄ gas flow rate of 2sccm) is introduced into PECVD chamber and the deposition time is only 30s, in which the carbon atoms diffuse into the Ni film and then segregate on its surface, forming single-layer or few-layer graphene. ► This investigation demonstrates that RF-PECVD technique is simple, low-cost, high-effective and reproducible for synthesizing graphene at relatively low temperature, compared to other CVD techniques.We present a simple, low-cost and high-effective method for synthesizing high-quality, large-area graphene using radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) on SiO₂/Si substrate covered with Ni thin film at relatively low temperatures (650°C). During deposition, the trace amount of carbon (CH₄ gas flow rate of 2sccm) is introduced into PECVD chamber and the deposition time is only 30s, in which the carbon atoms diffuse into the Ni film and then segregate on its surface, forming single-layer or few-layer graphene. After deposition, Ni is removed by wet etching, and the obtained single continuous graphene film can easily be transferred to other substrates. This investigation provides a large-area, low temperature and low-cost synthesis method for graphene as a practical electronic material.

Keywords: PECVD; Low temperature; Graphene

Monomolecular films of cholesterol oxidase and S-Layer proteins by Helen Conceição Ferraz; Juliana Aguilar Guimarães; Tito Livio Moitinho Alves; Carlos José Leopoldo Constantino (pp. 6535-6539).

► Reproducible and stable Langmuir films of cholesterol oxidase were obtained. ► S-Layer proteins extracted from Bacillus sphaericus were used to produce monolayers. ► S-Layer protein monolayers were also reproducible and very stable. ► No hysteresis was observed until a surface pressure of 15mNm⁻¹. ► Mixed films exhibiting an ideal-like behavior were obtained.Cholesterol oxidase (ChOx) is a flavoenzyme that catalyzes the oxidation of cholesterol to cholest-5-en-3-one and subsequently the isomerization to cholest-4-en-3-one. ChOx has been very commonly studied as the detection element in cholesterol biosensors. In the biosensor development field, a relatively new approach is the use of crystalline bacterial cell surface layers, known as S-Layer proteins. These proteins exhibit the ability of self-assembling at surfaces, opening a vast spectrum of applications, both in basic and applied researches. In our study, monomolecular films of ChOx and mixed films of ChOx/S-Layer proteins and DPPC/S-Layer proteins were produced using the Langmuir technique. Characterization of the films was performed by means of surface pressure–molecular area ( π– A) isotherms. Stable monolayers were obtained, which means that they can be transferred to solid substrates by Langmuir–Blodgett technique. Mixed monolayers showed an ideal like behavior.

Keywords: Cholesterol; Cholesterol oxidase; S-Layer proteins; Monolayer; Biosensor

Structural and photoluminescent properties of Ni doped ZnO nanorod arrays prepared by hydrothermal method by Liu Yanmei; Wang Tao; Sun Xia; Fang Qingqing; Lv Qingrong; Song Xueping; Sun Zaoqi (pp. 6540-6545).

► Ni doped ZnO nanorod arrays were synthesized by hydrothermal method. ► The position of their NBE peaks redshifts with the increase of Ni doping concentration. ► Ni-doping is beneficial to the enhancement of the crystal quality of ZnO nanorods. ► Ni-doping is also helpful to enhance photoluminescence of ZnO nanorods. ► The high excitation power is helpful to excite the impurity state related emissions.Self-assembled Ni-doped zinc oxide (Zn1−_xNi_xO, x=0.05, 0.10, 0.15, i.e., ZnNiO, nominal composition) nanorod arrays vertically grown on the ZnO seed layer covered glass along [001] direction were synthesized by hydrothermal method. Their images and structures have been characterized by scan electron microscope (SEM), X-ray diffraction (XRD) and Raman spectra, showing that Ni doping is beneficial to the formation of ZnO nanorods with hexagonal cross section and the enhancement of ZnO crystal quality. X-ray photoemission spectroscopy (XPS) study further demonstrated that Ni atoms were successfully doped into ZnO lattices. The photoluminescence (PL) spectra of ZnNiO samples show near bandedge emission (NBE) peaks at about 380nm at a low excitation power and the NBE peak position redshifts while its intensity continuously increases with the increase of Ni doping concentration. With the excitation power increasing, the NBE peak redshifts from 380nm to about 400nm for ZnNiO nanorod arrays. The NBE mechanisms for ZnNiO nanorod arrays have been discussed, which is helpful for understanding their room temperature ferromagnetisms.

Keywords: PACS; 81.07.−b; 78.55.Et; 61.05.cpPhotoluminescence; X-ray diffraction; Ni doped ZnO; Nanorod arrays

A density functional theory study on the H₂S molecule adsorption onto small gold clusters by Xiangjun Kuang; Xinqiang Wang; Gaobin Liu (pp. 6546-6553).

► The most favorable adsorption takes place between H₂S and even-numbered Au_n cluster. ► The small gold cluster would like to bond with sulfur. ► The Au_n structures and H₂S molecule still maintain their structural integrities. ► The reactivity enhancement of H₂S and strong gold–sulfur bond are observed. ► The scalar relativistic effect is favorable to the adsorption.An all-electron scalar relativistic calculation on Au_nH₂S ( n=1–13) clusters has been performed by using density functional theory with the generalized gradient approximation at PW91 level. The small gold cluster would like to bond with sulfur in the same plane and the H₂S molecule prefers to occupy the on-top and single fold coordination site in the cluster. The Au_n structures and H₂S molecule in all Au_nH₂S clusters are only slightly perturbed and still maintain their structural integrity. After adsorption, the S–H, H–H bond-lengths and most Au–Au bond-lengths are elongated, only a few Au–Au bond-lengths far from H₂S molecule are shortened. The reactivity enhancement of H₂S molecule is obvious and the strong gold–sulfur bond is observed expectedly. The most favorable adsorption takes place in the case that the H₂S molecule is adsorbed by an even-numbered Au_n cluster and becomes Au_nH₂S cluster with even number of valence electrons. It is believed that the strong scalar relativistic effect is favorable to H₂S molecule adsorption onto small gold clusters and is also one of the important reasons for the strong gold–sulfur bond.

Keywords: PACS; 73.22.−f, 36.40.Cg, 36.40.EiSmall gold clusters; H; ₂; S molecule; Adsorption; All-electron scalar relativistic calculations

Effects of oxygen partial pressure and substrate temperature on the structure and optical properties of Mg_xZn1−_xO thin films prepared by magnetron sputtering by Xinghua Zhang; Zunming Lu; Fanbin Meng; Yongzhong Wang; Ying Li; Xiao Yu; Chengchun Tang (pp. 6554-6559).

► The lattice constant and crystalline size of MgZnO thin films as a function of oxygen partial pressure and substrate temperature are investigated. ► Both the calculated and measured results show the ratio of Mg/Zn is influenced by the substrate temperature. ► The intensity of photoluminescence spectra is influenced by the oxygen partial and substrate temperature and associated with defect density and film quality.Deposited with different oxygen partial pressures and substrate temperatures, Mg_xZn1−_xO thin films were prepared using a Mg_0.6Zn_0.4O ceramic target by magnetron sputtering. The structural and optical properties of the prepared thin films were investigated. The X-ray diffraction spectra reveal that all the films on quartz substrate are grown along (200) orientation with cubic structure. The lattice constant decreases and the crystallite size increases with the increase of substrate temperature. Both energy dispersive X-ray spectroscopy and calculated results suggest the ratio of Mg/Zn increases with increasing substrate temperature. The thin film deposited with T_s=500°C has a minimal rms roughness of 7.37nm. The transmittance of all the films is higher than 85% in the visual region. The optical band gap is not sensitive to the oxygen partial pressure, while it increases from 5.63eV for T_s=100°C to 5.95eV for T_s=700°C. In addition, the refractive indices calculated from transmission spectra are sensitive to the substrate temperature. The photoluminescence spectra of Mg_xZn1−_xO thin films excited by 330nm ultraviolet light indicate that the peak intensity of the spectra is influenced by the oxygen partial pressure and substrate temperature.

Keywords: Magnetron sputtering; Transmission; Band gap; Photoluminescence

DNA adsorption and desorption on mica surface studied by atomic force microscopy by Lanlan Sun; Dongxu Zhao; Yue Zhang; Fugang Xu; Zhuang Li (pp. 6560-6567).

DNA adsorption and desorption on the mica surface have been studied. It is interesting that the desorption degree of DNA decreases as the DNA concentration increases. When DNA concentration is very low (1ng/μL), almost all of the DNA molecules have desorbed from the mica surface (as shown in above scheme). The further reasons of DNA adsorption and desorption on mica have been discussed in the article.Display Omitted► DNA adsorption and desorption on mica surface was studied by AFM. ► The influence of DNA concentration on DNA structure and desorption was investigated. ► Most stable DNA structure was found. ► Reason for DNA desorption degree was discussed.The adsorption of DNA molecules on mica surface and the following desorption of DNA molecules at ethanol–mica interface were studied using atomic force microscopy. By changing DNA concentration, different morphologies on mica surface have been observed. A very uniform and orderly monolayer of DNA molecules was constructed on the mica surface with a DNA concentration of 30ng/μL. When the samples were immersed into ethanol for about 15min, various desorption degree of DNA from mica (0–99%) was achieved. It was found that with the increase of DNA concentration, the desorption degree of DNA from the mica at ethanol–mica interface decreased. And when the uniform and orderly DNA monolayers were formed on the mica surface, almost no DNA molecule desorbed from the mica surface in this process. The results indicated that the uniform and orderly DNA monolayer is one of the most stable DNA structures formed on the mica surface. In addition, we have studied the structure change of DNA molecules after desorbed from the mica surface with atomic force microscopy, and found that the desorption might be ascribed to the ethanol-induced DNA condensation.

Keywords: Adsorption; Desorption; DNA; Ethanol; Mica; Atomic force microscopy

Preparation and photoelectrochemical performance of Ag/graphene/TiO₂ composite film by Gai Li; Teng Wang; Yi Zhu; Shengyi Zhang; Changjie Mao; Jieying Wu; Baokang Jin; Yupeng Tian (pp. 6568-6572).

► The Graphene/TiO₂ composite film was first prepared by dipping-lifting process. ► Then, the Ag/Graphene/TiO₂ composite film was fabricated by interface reaction. ► The photoelectrochemical conversion performance of the films was examined.By dipping-lifting in sol–gel solution and reducing process, the graphene/TiO₂ composite film on the glass plate was first prepared. Then, the Ag/graphene/TiO₂ composite film was fabricated by interface reaction with AgNO₃ and N₂H₄·H₂O on the surface of graphene/TiO₂ composite film. The characterization results show that the uniform porous TiO₂ film is made up of the anatase crystal, and the Ag/graphene/TiO₂ composite film is constructed by doping or depositing graphene sheets and Ag nanoparticles on the surface of TiO₂ film. The photoelectrochemical measurement results indicate that the Ag/graphene/TiO₂ composite film has an excellent photoelectrochemical conversion property.

Keywords: Graphene; TiO; ₂; Ag; Composite films; Photoelectrochemistry

The ferroelectric and ferromagnetic characterization of CoFe₂O₄/Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ multilayered thin films by Hong-li Guo; Guo Liu; Xue-dong Li; Hai-min Li; Wan-li Zhang; Jian-guo Zhu; Ding-quan Xiao (pp. 6573-6576).

► The multiferroic (PMN-PT/CFO)_n ( n=1,2) multilayered thin films have been prepared on SiO₂/Si(100) substrate with LNO as buffer layer via a rf magnetron sputtering method. ► The smooth, dense and crack-free surface shows the excellent crystal quality with root-mean-square (RMS) roughness only 2.9nm, and average grain size of CFO thin films on the surface is about 43.88nm. ► ( l00) orientation of the PMN-PT layers appear in the multilayered thin films, and the CFO layers in the multilayered thin ﬁlms with period n=1 show (400) and (311)-oriented. ► This multilayered thin films present ferromagnetic and ferroelectric properties, which become deteriorated with the increase of number n.The multiferroic (PMN-PT/CFO)_n ( n=1,2) multilayered thin films have been prepared on SiO₂/Si(100) substrate with LNO as buffer layer via a rf magnetron sputtering method. The structure and surface morphology of multilayered thin films were determined by X-ray diffraction (XRD) and atom force microscopy (AFM), respectively. The smooth, dense and crack-free surface shows the excellent crystal quality with root-mean-square (RMS) roughness only 2.9nm, and average grain size of CFO thin films on the surface is about 44nm. The influence of the thin films thickness size, periodicity n and crystallite orientation on their properties including ferroelectric, ferromagnetic properties in the (PMN-PT/CFO)_n multilayered thin films were investigated. For multilayered thin films with n=1 and n=2, the remanent polarization Pr are 17.9μC/cm² and 9.9μC/cm²; the coercivity H_c are 1044Oe and 660Oe, respectively. In addition, the relative mechanism are also discussed.

Keywords: rf magnetron sputtering; Ferroelectric thin films; RTA

Fabrication of flower-shaped Bi₂O₃ superstructure by a facile template-free process by Li Zhang; Yoshio Hashimoto; Toshinori Taishi; Isao Nakamura; Qing-Qing Ni (pp. 6577-6582).

.Display Omitted► A novel flower-shaped Bi2O3 superstructure has been successfully synthesized by calcination of the precursor, which was prepared via a citric acid assisted hydrothermal process. ► Key factors for the formation of the Bi2O3 superstructures have been proposed; a mechanism for the growth of the superstructure has been presented based on the FESEM investigation of different growth stages.A novel flower-shaped Bi₂O₃ superstructure has been successfully synthesized by calcination of the precursor, which was prepared via a citric acid assisted hydrothermal process. The precursor and Bi₂O₃ were characterized with respect to morphology, crystal structure and elemental chemical state by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It was shown that both the precursor and Bi₂O₃ flower-shaped superstructure were constructed of numerous nanosheets while the nanosheets consisted of a great deal of nanoparticles. Furthermore, key factors for the formation of the superstructures have been proposed; a mechanism for the growth of the superstructure has been presented based on the FESEM investigation of different growth stages.

Keywords: Bi; ₂; O; ₃; Superstructure; Hydrothermal

Synthesis of cauliflower-like ZnO–TiO₂ composite porous film and photoelectrical properties by Yinhua Jiang; Yun Yan; Wenli Zhang; Liang Ni; Yueming Sun; Hengbo Yin (pp. 6583-6589).

Display Omitted► The novel cauliflower-like TiO₂–ZnO films were successfully fabricated. ► This cauliflower-like morphology of TiO₂–ZnO could increase the dye absorption. ► The effects of ZnO doping on the photovoltaics of DSCs were systematically studied. ► With Zn/Ti molar ratio not more than 3%, the J_sc and η of DSC were greatly improved.A series of cauliflower-like TiO₂–ZnO composite porous films with various molar ratios of Zn/Ti were prepared by the screen printing technique on the fluorine-doped SnO₂ (FTO) conducting glasses. The composite films were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray energy-dispersive spectrometry (EDS) and UV–vis transmittance spectrum. The results showed composite film electrode had a novel cauliflower-like morphology, which could effectively increase the dye absorption. The corresponding dye-sensitized solar cells (DSCs) were made by the composite film, and effects of ZnO incorporation on the photovoltaic performances of the DSCs were studied. With the Zn/Ti molar ratio not more than 3% in ZnO–TiO₂ composite film of about 5μm-thickness, the photocurrent density ( J_sc) and the solar-to-electricity conversion efficiency ( η) were greatly improved compared with those of the DSC based on bare TiO₂ film of same thickness. This increases in efficiency and J_sc were attributed to high electron conductivity of ZnO, the improved dye adsorption and large light transmittance of composite film.

Keywords: ZnO doping; Cauliflower-like; Composite porous films; Photoelectrical performances

The super hydrophobicity of ZnO nanorods fabricated by electrochemical deposition method by Geping He; Kaige Wang (pp. 6590-6594).

► Different aspect ratios ZnO nanorods are fabricated by electrochemical deposition. ► Deposition time and temperature affect nanorod height instead of diameter. ► ZnO nanorods hydrophobicity will be increased with aspect ratios increasing. ► Surface larger hydroxyl density enables nanorods hydrophilic.Electrochemical deposition method was employed to fabricate ZnO nanorods on zinc foil substrate in this paper. The structural observations of ZnO nanorods with different aspect ratios were carried out by field-emission scanning electron microscopy. The microstructures of ZnO nanorods were also characterized by X-ray diffraction and the changes in surface hydroxyls with electrochemical deposition time were analyzed by X-ray photoelectron spectroscopy. The study results show the aspect ratios of ZnO nanorods and the density of their surface hydroxyls are responsible for their superhydrophobicity. The fluorinated polymer coated ZnO nanorods showed an excellent superhydrophobic behavior with 167° contact angle of water droplet, which is larger than that of fluorinated polymer flat surface. The more the surface hydroxyls are, the more hydrophilic the surfaces are. Meanwhile, the larger the aspect ratio of ZnO nanorod arrays is, the larger its drophobicity is. The results of this study might pave a simple and feasibility pathway to the fabrication of superhydrophobic cleaning materials used in engineering fields.

Keywords: ZnO nanorods; Superhydrophobic; Electrochemical deposition

One-pot solvothermal route to self-assembly of cauliflower-shaped CdS microspheres by Ming Ge; Yao Cui; Lu Liu; Zhen Zhou (pp. 6595-6600).

► Nearly monodispersed cauliflower-shaped CdS microspheres were synthesized through a facile one pot solvothermal route on a large scale. ► The possible formation mechanism of the cauliflower shaped CdS microspheres was discussed in detail. ► The as-obtained cauliflower-shaped CdS nanostructures exhibited higher photovoltaic performance compared with CdS nanoparticles.Nearly monodispersed cauliflower-shaped CdS microspheres were prepared through a simple one-step solvothermal route on a large scale by employing sodium dodecyl sulfate (SDS) as the surfactant. Images by field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) indicate that cauliflower-shaped CdS microspheres with diameters in the range from 1.3 to 4.5μm are assembled by nanoparticles with an average diameter of approximately 30nm. The possible formation mechanism of the cauliflower-shaped CdS microspheres was also proposed. The photovoltaic activity of cauliflower-shaped CdS architectures has been investigated, indicating that the as-obtained CdS microspheres exhibited higher photovoltaic performance in comparison with CdS nanoparticles.

Keywords: Cadmium sulfide; Solvothermal method; Cauliflower-shaped microspheres; Self-assembly; Photovoltaic property

Laser induced activation of circuit lines and via-holes on AlN for electroless metal plating by Kam Cheun Yung; Cong Chen; Chung Pang Lee (pp. 6601-6606).

► The research results on fine lines show the relations between the quality of copper metallization and laser wavelengths, energy density, repetition rate and repetition. ► Metallic aluminium produced by decomposition of AlN on local laser irradiated surfaces is proven with the XPS data and is seen to be the electron supplier and catalyzing center for electrochemical reactions in electroless copper bath. ► Blind, through-hole and V-shaped micro via-holes show depth-dependent activation and metallization.Laser induced activation of fine lines and micro via-holes on aluminium nitride for electroless copper plating is studied. Differing from traditional techniques, this method is demonstrated as an additive and precursorless process, which requires fewer processing steps with good reliability. Ultraviolet, visible and infrared lasers are applied to activate aluminium nitride surfaces. The relations between the quality of activation and laser wavelength, energy density, repetition rate and repetition are described. Depth-dependent activation and metallization of micro via-holes in aluminium nitride using this method are observed and reported for the first time.

Keywords: Keyword; Laser; Activation; Ablation; Micro via-hole; Fine line; Metallization

Au adsorption and Au-mediated charge transfer on the SrO-termination of SrTiO₃ (001) surface by Wei Wei; Ying Dai; Meng Guo; Baibiao Huang (pp. 6607-6611).

► Au plays as electron trapping center on SrTiO₃ (001) surface. ► Au mediates the charge transfer from electron-doped SrTiO₃ to NO. ► Photogenerated electron-hole pairs can be effectively separated due to Au. ► Photocatalytic efficiency can be greatly improved due to Au adsorption.Atomic Au adsorption on the SrO-termination of SrTiO₃ (001) surface has been studied by means of the first-principles calculations based on the density functional theory (DFT). It indicates that charge polarization dominantly contributes to the bonding between Au and SrO-termination. Interfacial charge transfer induces dipole moment and changes work function. The mediating role Au played in charge transfer from electron-doped SrTiO₃:Nb to NO has been simulated. Charge transfer from SrTiO₃:Nb to Au is ascertained indicating that Au plays as an electron trapping center. SrO-termination has weak activity to NO while the molecule can be strongly adsorbed on negatively charged Au atom. It has been represented that Au mediates the charge transfer from SrTiO₃:Nb to NO. Antibonding orbital (π_2p*) of NO accommodates the charge and thus molecular bond is weakened (activated). Fukui functions demonstrate the role Au played in transiting the charge transfer from electronically excited SrTiO₃ to target species. Evidence that metal deposited on photocatalyst surface effectively separates the electron–hole pairs and improves the photocatalytic activity is presented in the current work.

Keywords: SrTiO; ₃; (0; 0; 1) surface; Au adsorption; Charge transfer; DFT calculation

Transparent titania nanotubes of micrometer length prepared by anodization of titanium thin film deposited on ITO by Siew Leng Lim; Yiliang Liu; Jing Li; En-Tang Kang; Chong Kim Ong (pp. 6612-6617).

► Anodization of RF sputtered Ti film on ITO glass. ► Electrolyte consisting of 0.75% (wt) NH₄F and 2% (vol) H₂O dissolved in ethylene glycol and anodization voltage of 40V is optimal for TiO₂ nanotube formation. ► Upper nanoporous layer are formed on top of top of well ordered and regular TiO₂ nanotubes. ► Annealed nanotubes demonstrate lower transmittance than non annealed nanotubes in the visible region.Transparent TiO₂ nanotube arrays of micrometer lengths were prepared by anodization of titanium thin film RF sputtered on indium tin oxide (ITO) which was coated on glass substrate. The sputtering process took place at elevated temperature of 500°C. The structures of the films were studied using scanning electron microscopy (SEM) and X-ray diffraction (XRD) while the optical properties of the films were investigated using UV–visible spectroscopy. Two types of electrolytes were used in this work: an aqueous mixture of acetic acid and HF solution and a mixture of NH₄F and water dissolved in ethylene glycol. The concentration of NH₄F, voltage and the thickness of the sputtered titanium film were varied to study their effect on the formation of TiO₂ nanotube arrays. It is demonstrated in this work that the nanoporous layer is formed on top of the ordered array of TiO₂ nanotubes. Furthermore, the optical transmittance of TiO₂ nanotubes annealed at 450°C is much lower than the non annealed TiO₂ nanotubes in the visible wavelength region.

Keywords: Transparent TiO; ₂; nanotube arrays; Anodization of titanium thin film; RF sputtered; Indium tin oxide

Friction and wear properties of hybrid sol–gel nanocomposite coatings against steel: Influence of their intrinsic properties by Cindy Belon; Marjorie Schmitt; Sophie Bistac; Céline Croutxé-Barghorn; Abraham Chemtob (pp. 6618-6625).

► Organic–inorganic hybrid coatings. ► UV curing process coupled with the mixing of an epoxy resin with epoxysilanes. ► Friction mechanisms.A dual UV-curing process inducing in a single step cationic photopolymerization and a photoinduced sol–gel process was used to obtain novel hybrid coatings. For this, an epoxy resin based on hydrogenated diglycidyl ether bisphenol A was mixed with an epoxy trimethoxysilane precursor (GPTMS, TRIMO) in the presence of photoacid generator based on diaryliodonium salt. Various UV-cured coatings were prepared with different amounts of the hybrid monomer (20 and 50wt%), and two thicknesses: 15 and 80μm. The friction and wear properties of these coatings were characterized on a ball-on-disc tribometer (steel ball; applied normal load: 6N; sliding speed: 5cm/s). Both the coating thickness and the addition of the hybrid monomer tend to improve the stiffness of the pure epoxy resin; however, these two parameters also induce an increase of the dynamic friction value.

Keywords: Photopolymerization; Epoxysilanes sol–gel; Friction mechanisms

Novel PdAgCu ternary alloy: Hydrogen permeation and surface properties by Ana M. Tarditi; Fernando Braun; Laura M. Cornaglia (pp. 6626-6635).

► PdAgCu membranes were prepared by sequential electroless plating technique. ► Hydrogen permeabilities of PdAgCu_FCC alloy were higher than permeabilities of PdCu_FCC membranes. ► Both XRD and XPS provided evidence of the PdAgCu_FCC ternary alloy formation. ► Ag and Cu co-segregation to the surface takes place under hydrogen permeation experiments.Dense PdAgCu ternary alloy composite membranes were synthesized by the sequential electroless plating of Pd, Ag and Cu on top of both disk and tubular porous stainless steel substrates. X-ray diffraction and scanning electron microscopy were employed to study the structure and morphology of the tested samples. The hydrogen permeation performance of these membranes was investigated over a 350–450°C temperature range and a trans-membrane pressure up to 100kPa. After annealing at 500°C in hydrogen stream followed by permeation experiments, the alloy layer presented a FCC crystalline phase with a bulk concentration of 68% Pd, 7% Ag and 25% Cu as revealed by EDS. The PdAgCu tubular membrane was found to be stable during more than 300h on hydrogen stream. The permeabilities of the PdAgCu ternary alloy samples were higher than the permeabilities of the PdCu alloy membranes with a FCC phase. The co-segregation of silver and copper to the membrane surface was observed after hydrogen permeation experiments at high temperature as determined by XPS.

Keywords: Palladium ternary alloys; Hydrogen separation membranes; PdAgCu

Surface reaction characteristics at low temperature synthesis BaTiO₃ particles by barium hydroxide aqueous solution and titanium tetraisopropoxide by Min Zeng (pp. 6636-6643).

► BaTiO₃ nano-particles can be synthesized at low temperature by reaction between Ba(OH)₂ solution and TTIP. ► By determining the PZC and the OH⁻ ions adsorption, we studied the TiO₂ precipitate surface characteristics. ► The concentration changes of [Ba²⁺] during the reaction process were measured. ► The heterogeneous nucleation occurred on the titania surface using the Avrami's equation.Well-crystallized cubic phase BaTiO₃ particles were prepared by heating the mixture of barium hydroxide aqueous solution and titania derived from the hydrolysis of titanium isopropoxide (TTIP) at 328K, 348K or 368K for 24h. The morphology and size of obtained particles depended on the reaction temperature and the Ba(OH)₂/TTIP molar ratio. By the direct hydrolytic reaction of titanium tetraisopropoxide, the high surface area titania (TiO₂) was obtained. The surface adsorption characteristics of the titania particles had been studied with different electric charges OH⁻ ions or H⁺ ions. The formation mechanism and kinetics of BaTiO₃ were examined by measuring the concentration of [Ba²⁺] ions in the solution during the heating process. The experimental results showed that the heterogeneous nucleation of BaTiO₃ occurred on the titania surface, according to the Avrami's equation.

Keywords: BaTiO; ₃; Synthesis; TTIP; Avrami's equation; Surface characteristics

The influences of the local impact site and incident energy on the transport behaviors of single copper atom onto Cu (001) surface by Xing-bin Jing; Zu-li Liu; He-lin Wei; Kai-lun Yao (pp. 6644-6649).

► Both the local impact site and incident energy could influence on transport behaviors of a single deposited Cu atom onto Cu (001). ► The observed transport behaviors of the deposited atom include: direct adsorption (DA), penetration by atomic exchange, and transient penetration (TP). ► The maximum increment of kinetic energy at every impact site approaches to a certain value except for the incident energy below 2.0eV. ► Transport behaviors of the incident atoms are possibly attributed to the dynamical competition between the deposited atom and substrate atoms.Molecular dynamics (MD) simulation is carried out to study the transport behaviors of a single deposited atom in Cu film homoepitaxy. We consider the normal Cu incident atoms impinging on the Cu (001) surface at four possible local impact sites (top, bridge, hollow and general). The observed transport behaviors of the deposited atom onto the surface include: direct adsorption (DA), penetration by atomic exchange, and transient penetration (TP), which a deposited atom penetrates the interstitial site and then rapidly migrates to a stable site on the surface. The results show that transport behaviors of the deposited atom are closely related to both the local impact site and the incident energy. The maximum increment of kinetic energy at every impact site approaches to a certain value except for the incident energy below 2.0eV. Furthermore, as the incident energy is higher than the penetration threshold, TP behavior could be observed again in some energy ranges. This interesting phenomenon, which cannot be explained by the existing theories, is possibly attributed to the dynamical competition between the deposited atom and substrate atoms.

Keywords: PACS; 68.35.Fx, 71.15.Pd, 81.15.KkMolecular dynamics simulation; Transport behavior; Surface; Penetration

Laser-induced forward transfer of focussed ion beam pre-machined donors by K.S. Kaur; M. Feinaeugle; D.P. Banks; J.Y. Ou; F. Di Pietrantonio; E. Verona; C.L. Sones; R.W. Eason (pp. 6650-6653).

► LIFT printing of ZnO films pre-machined using the focussed ion beam technique. ► Debris-free micro-pellets with extremely smooth edges were transferred. ► Comparison with printing of non-machined and DRL- assisted films is presented.In this paper we report femtosecond laser-induced forward transfer (LIFT) of pre-machined donor films. 1μm thick zinc oxide (ZnO) films were first machined using the focussed ion beam (FIB) technique up to a depth of 0.8μm. Debris-free micro-pellets of ZnO with extremely smooth edges and surface uniformity were subsequently printed from these pre-machined donors using LIFT. Printing results of non-machined ZnO donor films and films deposited on top of a polymer dynamic release layer (DRL) are also presented for comparison, indicating the superior quality of transfer achievable and utility of this pre-machining technique.

Keywords: Laser induced forward transfer (LIFT); Focussed ion beam (FIB); ZnO; DRL

Synthesis of well-defined structurally silica–nonlinear polymer core–shell nanoparticles via the surface-initiated atom transfer radical polymerization by Jiucun Chen; Min Hu; Wendong Zhu; Yaping Li (pp. 6654-6660).

► We report herein the well-defined structurally silica–nonlinear polymer core–shell nanoparticles via the surface-initiated atom transfer radical polymerization. ► The obtained particles had clear core–shell structure and may be used as biolabeling materials. ► This three-step route may also be used to synthesize other core–shell particles and offer new opportunities for a wide range of application.We report on the synthesis of the well-defined structurally silica–nonlinear polymer core–shell nanoparticles via the surface-initiated atom transfer radical polymerization. At first, 3-(2-bromoisobutyramido)propyl(triethoxy)-silane (the ATRP initiator) was prepared by the reaction of 3-aminopropyltriethoxysilane with 2-bromoisobutyryl bromide. The ATRP initiator was covalently attached onto the nanosilica surface. The subsequent ATRP of HEMA from the initiator-attached SiO₂ surface was carried out in order to afforded functional nanoparticles bearing a hydroxyl moiety at the chain end, SiO₂-g-PHEMA-Br. The esterification reaction of pendent hydroxyl moieties of PHEMA segment with 2-bromoisobutyryl bromide afforded the SiO₂-based multifunctional initiator, SiO₂-g-PHEMA(-Br)-Br, bearing one bromine moiety on each monomer repeating unit within the PHEMA segment. Finally, the synthesis of SiO₂-g-PHEMA(-g-PSt)-b-PSt was accomplished by the ATRP of St monomer using SiO₂-g-PHEMA(-Br)-Br as multifunctional initiator. These organic/inorganic hybrid materials have been extensively characterized by FT-IR, XPS, TG, and TEM.

Keywords: Core–shell structure; Silica; Surface-initiated atom transfer radical polymerization; Hybrid nanoparticles

¹¹C-radiolabeling study of methanol decomposition on copper oxide modified mesoporous SBA-15 silica by Tanya Tsoncheva; Eva Sarkadi-Priboczki (pp. 6661-6666).

. The nature of the primary product of methanol decomposition is related to the overall coverage of the surface with methanol and to the adsorption ability of the supported copper species.Display Omitted► Novel¹¹C-labeling technique for methanol decomposition on CuO/SBA-15 investigation. ► Methyl formate forms via dimmerization of formaldehyde molecules on the strongest sites. ► Dimethoxymethane forms with the activity of weakly adsorbed methanol molecules. ► CO2 forms via dioxymethylene intermediates by oxygen transfer from the copper oxide.¹¹C-radiolabeling technique is applied to investigate methanol decomposition on copper oxide modified SBA-15. Nitrogen physisorption, XRD, FTIR, UV–vis and TPR techniques are used for catalyst characterization. Selective adsorption coverage of the catalytic active sites with¹¹C- and¹²C-methanol molecules is carried out and the products of their conversion are followed. The mechanism of methyl formate, methylal and CO₂ formation from methanol is discussed.

Keywords: Copper oxide modified SBA-15; Methanol decomposition; ¹¹; C-radiolabeling study

Anodic oxidation of anthraquinone dye Alizarin Red S at Ti/BDD electrodes by Jianrui Sun; Haiyan Lu; Lili Du; Haibo Lin; Hongdong Li (pp. 6667-6671).

► The preparation of Ti/BDD with high quality. ► Studied the reaction mechanism and kinetics of the ARS oxidation in detail. ► Ti/BDD possess high activity for the treatment of environmental wastewater.The boron-doped diamond (BDD) thin-film electrode with high quality using industrially titanium plate (Ti/BDD) as substrate has been prepared and firstly used in the oxidation of anthraquinone dye Alizarin Red S (ARS) in wastewaters. The Ti/BDD electrodes are shown to have high concentration of sp³-bonded carbon and wide electrochemical window. The results of the cyclic voltammetries show that BDD has unique properties such as high anodic stability and the production of active intermediates at the high potential. The oxidation regions of ARS and water are significantly separated at the Ti/BDD electrode, and the peak current increases linearly with increasing ARS concentration. The bulk electrolysis shows that removal of chemical oxygen demand (COD) and color can be completely reached and the electrooxidation of ARS behaves as a mass-transfer-controlled process at the Ti/BDD electrode. It is demonstrated that the performances of the Ti/BDD electrode for anodic oxidation ARS have been significantly improved with respect to the traditional electrodes.

Keywords: Boron doped diamond; Electrochemical characteristics; Cyclic voltammetry; Electrochemical oxidation

Preparation and characterization of vinyl-functionalized carbon spheres by allylamine by Xingmei Guo; Yongzhen Yang; Xuguang Liu (pp. 6672-6677).

► Oxygen-containing groups were introduced onto the surface of carbon spheres by nitric acid treatment, which improving the hydrophilic property of the surface of carbon spheres dramatically and lay the foundation of grafting allylamine. ► Vinyl groups were introduced on the surface of carbon spheres by allylamine. ► Vinyl-functionalized carbon spheres show good dispersion in organic solvent such as CHCl₃ and THF.Carbon spheres (CSs) were synthesized by chemical vapor deposition in Ar atmosphere using acetylene as carbon source. Vinyl-functionalized CSs was prepared by nitric acid oxidation and reacting with allylamine. The morphology, structure and effect of functionalization of CSs at different processing steps were characterized using field-emission scanning electron microscopy, Fourier-transform IR spectra, X-ray photoelectron spectroscopic and thermogravimetric analysis. The results show that some oxygen-containing groups such as carboxyl and hydroxyl were produced on the surface of CSs by nitric acid treatment, and vinyl groups were introduced on the surface of CSs by allylamine treatment. Acid-treated CSs are well dispersed in water and allylamine-treated CSs are well dispersed in organic solvent, which is preconditions of reactivity of CSs in liquid phase and lays the basis for the application of CSs.

Keywords: Carbon spheres; Oxidation; Vinyl; Functionalization; Allylamine

Growth of hierarchical based ZnO micro/nanostructured films and their tunable wettability behavior by P. Suresh Kumar; A. Dhayal Raj; D. Mangalaraj; D. Nataraj; N. Ponpandian; Lin Li; G. Chabrol (pp. 6678-6686).

► A simple two step method was adopted to fabricate hierarchical ZnO nanostructured film onto different annealed ZnO seed layer films. ► The surface morphology analysis revels the formation of complex hierarchical ZnO structured films with plates to hexagonal rod crystal and to tube-like structure without any surface modification and treatments. ► The present approach demonstrates its potentiality for low-temperature and large-scale synthesis of hierarchical ZnO ﬁlms for future self-cleaning application.Hierarchical zinc oxide (ZnO) micro/nanostructured thin films were grown onto as-prepared and different annealed ZnO seed layer films by a simple two step chemical process. A cost effective successive ionic layer adsorption and reaction (SILAR) method was employed to grow the seed layer films at optimal temperature (80°C) and secondly, different hierarchical based ZnO structured thin films were deposited over the seed layered films by chemical bath deposition (CBD). The influence of seed layer on the structural, surface morphological, optical and wettability behavior of the ZnO thin films were systematically investigated. The XRD analysis confirms the high crystalline nature of both the seed layer and corresponding ZnO micro/nanostructured films with a perfect hexagonal structure oriented along (002) direction. The surface morphology revels a complex and orientated hierarchical based ZnO structured films with diverse shapes from plates to hexagonal rod-like crystal to tube-like structure and even much more complex needle-like shapes during secondary nucleation, by changing the seed layer conditions. The water contact angle (WCA) measurements on hierarchical ZnO structured films are completely examined to study its surface wettability behavior for its suitability in future self-cleaning application. Photoluminescence (PL) spectra of the ZnO structured film exhibit UV and visible emissions in the range of 420–500nm. The present approach demonstrates its potential for low-temperature, large-scale, controlled synthesis of crystalline hierarchical ZnO nanostructures films.

Keywords: Hierarchical ZnO films; Chemical process; Surface analysis; Wettability

A combined study of the oxidation mechanism and resistance of AISI D6 steel exposed at high temperature environments by G. Vourlias; D. Chaliampalias; T.T. Zorba; E. Pavlidou; P. Psyllaki; K.M. Paraskevopoulos; G. Stergioudis; K. Chrissafis (pp. 6687-6698).

► In this work the oxidation mechanism in D6 steel through combined study of reaction kinetics and the identification of the oxidation products formed during the oxidation at high temperature is investigated. ► The results offer important information for the determination of the temperature range in which it can work safely is made and for service life. ► The structure of the particular steel was found to contain big size chrome carbides and smaller tungsten carbides which were dispersed in the metal matrix of the material. ► D6 steel was found to be resistant up to 830°C. ► At higher temperatures several structural changes happen, such as decarburization or intense oxidation of the preexisting carbides.In this work it is thoroughly examined the oxidation performance of D6 tool steel under isochronal and isothermal oxidations. Isochronal oxidation tests, from ambient temperature to 1000°C, revealed the oxidation rate of the coupons at different temperatures. Four different temperatures were selected for the isothermal oxidation test, which correspond to different oxidation rates. The oxidation and the examination of the samples were accomplished by thermogravimetric analysis (TG) in air with which the mass gain of the samples due to oxidation was simultaneously acquired. The samples were, also, examined by scanning electron microscopy (SEM), in order to observe their surface before and after the oxidation tests. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used for the accurate identification of the as formed oxides. The results revealed that in every case two distinct layers of oxides were formed while their composition was different, depending on the temperature of oxidation. Furthermore, the thickness of the as formed oxides is increased when the oxidation is performed at higher temperatures.

Keywords: PACS; 68.37.Hk; 81.65.Mq; 81.65.Kn; 81.70.PgMetals and alloys; Microstructure; Scanning electron microscopy; Fourier transform infrared spectroscopy; Thermogravimetric measurements

Green luminescence from triphenylphosphine functionalized single-wall carbon nanotubes by Rima Paul; P. Kumbhakar; A.K. Mitra (pp. 6699-6703).

Display Omitted► Simple chemical precipitation technique to synthesize SWCNT/triphenylphosphine (Ph₃P) nanohybrid. ► Triphenylphosphine (Ph₃P) nanocrystals of average size 27nm are attached to SWCNT surfaces. ► SEM/EDAX, HRTEM, FTIR and Raman spectroscopy confirm the nanostructure. ► Green photoluminescence in 450–575nm range with peak emission at 500nm. ► May find wide applications in sensor-based devices.In a simple wet chemical process, purified single-wall carbon nanotubes (SWCNTs) are treated with triphenylphosphine (Ph₃P) at room temperature. The functionalized material is characterized by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. HRTEM micrograph clearly reveals that triphenylphosphine nanocrystals of nearly uniform size are attached to the surfaces of SWCNTs. The hybrid structure shows remarkable green luminescence with peak emission at around 500nm, under UV excitation. The photoluminescence may be attributed to charge transfer from the electron-donating phosphorous atoms to the carbon nanotubes.

Keywords: SWCNT; Triphenylphosphine; Optical property; HRTEM

A facile method for grafting of bisphenol A imprinted polymer shells onto poly(divinylbenzene) microspheres through precipitation polymerization by Yongxiang Wang; Qiuming Liu; Fei Rong; Degang Fu (pp. 6704-6710).

► We directly graft bisphenol A imprinted polymer onto poly(divinylbenzene). ► Core–shell structures depend on the concentration of cores and precursor. ► These particles show clear selectivity to bisphenol A in solid-phase extraction. ► Leak of bisphenol A from these particles is not found after extraction.Core–shell structured polymers are usually prepared by “grafting to” or “grafting from” techniques, wherein polymer supports were first modified by vinyl bonds or initiators. Success can be immediate, but more often a learning curve needs to be traversed. In this paper, direct grafting bisphenol A imprinted polymer onto poly(divinylbenzene) microspheres through precipitation polymerization is introduced. The obtained microspheres were characterized by SEM, TEM, FTIR and BET. Firstly, mono-disperse poly(divinylbenzene) microspheres of 3μm in size were prepared by precipitation polymerization. The solvent for grafting was then optimized and it was found that the mixtures of toluene and acetonitrile (30/70, v/v) were ideal choice from the image and structure analysis of the shells. Shells of different thickness (270–840nm), depending on the concentrations of monomers in the precursor, were then directly grafted to the microspheres by a reactive, entropic capture mechanism. The recognition ability of the microspheres was evaluated by solid-phase extraction and clear selectivity showed toward bisphenol A. The leak of bisphenol A was not found after extraction and thus these core–shell structured imprinted polymers are believed to have potential applications in trace analysis area.

Keywords: Core–shell structures; Grafting; Molecular imprinting; Bisphenol A; Precipitation polymerization

Preparation, characterization and MRI application of carboxymethyl dextran coated magnetic nanoparticles by G. Liu; R.Y. Hong; L. Guo; Y.G. Li; H.Z. Li (pp. 6711-6717).

► CM-dextran coated MNPs were prepared by a two-step method. ► CM-dextran coated MNPs showed superparamagnetism and were stable over the entire range of pH and NaCl concentration in water. ► CM-dextran coated MNPs exhibited excellent MRI property and could potentially be used as MRI contrast agents for magnetic resonance molecular imaging.Superparamagnetic nanoparticles functionalized with carboxymethyl dextran (CM-dextran) were synthesized by a two-step method. First, the magnetic nanoparticles (MNPs) coated with dextran ( M_w≈20000) were prepared by co-precipitation of Fe²⁺ and Fe³⁺ ions. Then, dextran on the surface of MNPs reacted with monochloroacetic acid (MCA) in alkaline condition. The influences of temperature and reactant concentration on the amount of –COOH on the surface of nanoparticles were systematically studied. The obtained MNPs coated with CM-dextran were stable over the entire range of pH and NaCl concentration. The MRI experiment indicated that the CM-dextran MNPs could potentially be used as MRI contrast agents for magnetic resonance molecular imaging.

Keywords: Carboxymethyl dextran; Monochloroacetic acid; MRI; Magnetic nanoparticle

Investigation on periodic cracking of elastic film/substrate system by the extended finite element method by Xueling Fan; Weixu Zhang; Tiejun Wang; Guiwu Liu; Jinghua Zhang (pp. 6718-6724).

► Periodic cracking in film/substrate system. ► Crack length and periodic crack spacing are key factors. ► Crack spacing has a saturation value. ► Multiple cracks can extend the durability of film/substrate system.Multiple cracking behavior in a thin elastic film bonded to a thick elastic substrate is investigated by the extended finite element method. Stress and stress intensity factor are obtained using a periodic finite element model for the cracked film/substrate system. The influences of various parameters including crack length, film thickness, periodic crack spacing, and relative stiffness of the substrate on the stress and stress intensity factor are discussed in detail. It is demonstrated that the effects of geometric parameters are more sensitive than that of material property. In particular, the crack spacing has a saturation value due to interactions of neighboring cracks and relief of tensile stress in the film. The film/substrate couple with multiple periodic cracks can exhibit a positive potential in improving the durability of the film/substrate system.

Keywords: Periodic crack; Film; Substrate; Stress; Finite element method

Preparation, characterization and surface morphology of novel optically active poly(ester-amide)/functionalized ZnO bionanocomposites via ultrasonication assisted process by Amir Abdolmaleki; Shadpour Mallakpour; Sedigheh Borandeh (pp. 6725-6733).

Novel poly(ester-amide)/ZnO bionanocompoites were prepared by using ZnO nanoparticles functionalized with γ-methacryloxypropyltrimethoxysilane (KH570). The results show the nano scale and homogeneous dispersion of modified ZnO in polymer matrix.Display Omitted► Preparation of new PEA/ZnO bionanocomposites using modified ZnO nanoparticles with KH570 via ultrasonic as a versatile tool for the synthesis of bionanocomposite polymers. ► The resulting bionanocomposites were fully characterized by various techniques such as FT-IR, XRD, TGA and their morphology was studied by FE-SEM, AFM and TEM analyses. ► All data indicate that the nanoparticles were dispersed homogeneously in PEA matrix on nanoscale. ► Due to the existence of amino acid in the backbone of obtained PEA, it is predictable to be biodegradable and biocompatible. Also because the ZnO nanoparticles is environmentally friendly so it would be suitable to name these nanocomposites, as PEA/ZnO bionanocomposite polymers.Novel bionanocompoites (BNCs) were prepared using zinc oxide (ZnO) nanoparticles which functionalized by γ-methacryloxypropyltrimethoxysilane (KH570) as a coupling agent. Poly(ester-amide) (PEA) based on tyrosine natural amino acid was synthesized and used as a polymer matrix. PEA/ZnO BNCs were characterized by fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). All the results confirmed that the surface of ZnO particle has sufficient compatibility with PEA through the link of the coupling agent between ZnO and polymer and also proved that the presence of ZnO nanoparticles appeared to be dispersed in nanosize in polymer composite matrix. In addition, thermogravimetric analysis (TGA) data indicated an enhancement of thermal stability of new BNC materials compared with the pure polymer.

Keywords: Zinc oxide (ZnO) nanoparticle; Bionanocomposite; Poly(ester-amide); Coupling agent; γ-Methacryloxypropyltrimethoxysilane; Tyrosine natural amino acid

Microwave-assisted activation for electroless nickel plating on PMMA microspheres by Yen-Chung Chen; Robert Lian-Huey Liu; Xin-Liang Chen; Hsiou-Jeng Shu; Ming-Der Ger (pp. 6734-6740).

► Microwave-assisted activation method for electroless plating.► Pd with a size of 4–6nm uniformly distributed on the surfaces of the PMMA microspheres.► Nickel–phosphorus alloy coating on the PMMA microspheres.A novel microwave-assisted activation method for electroless plating on PMMA microspheres is presented in this study. When the microwave irradiation was applied during the activation step, the amount of the Pd species adsorbed on PMMA surfaces was much higher than that of sample pretreated with a conventional activation process without microwave irradiation. With this activation method, it was also shown that the adsorbed Pd species with a size of 4–6nm were uniformly distributed on the surfaces of the PMMA microspheres, thus a smooth and uniform nickel–phosphorus coating on the PMMA microspheres was obtained by subsequent electroless plating. The samples after each step were characterized by XPS, TEM, ICP and SEM.

Keywords: Polymethylmethacrylate (PMMA); Electroless plating; Activation; Microwave irradiation

Preparation and annealing study of TaN_x coatings on WC-Co substrates by Yung-I Chen; Bo-Lu Lin; Yu-Chu Kuo; Jen-Ching Huang; Li-Chun Chang; Yu-Ting Lin (pp. 6741-6749).

► TaN_x coatings served as diffusion barriers for Co during 500 and 600°C annealing. ► The columnar structure provided fast channels for oxygen diffusion in air annealing. ► The in-diffusion of oxygen is restricted in a glass molding, 50ppm O₂–N₂ atmosphere.To prevent Co diffusion from cemented carbides at high temperatures, we fabricated TaN_x coatings by reactive direct current (d.c.) magnetron sputtering onto 6wt.% cobalt cemented carbide substrates, to form diffusion barrier layers. Varying the nitrogen flow ratio, N₂/(Ar+N₂), from 0.05 to 0.4 during the sputtering process had a significant effect on coating structure and content. Deposition rate reduced as the nitrogen flow ratio increased. The effects of nitrogen flow ratio on the crystalline characteristics of the TaN_x coatings were examined by X-ray diffraction. The TaN_x coatings annealing conditions were 500, 600, 700, and 800°C for 4h in air. We evaluated the performance of the diffusion barrier using both Auger electron spectroscopy depth-profiles and X-ray diffraction techniques. We also investigated oxidation resistance of the TaN_x coatings annealed in air, and under a 50ppm O₂–N₂ atmosphere, to evaluate the fabricated layers effectiveness as a protective coating for glass molding dies.

Keywords: TaN; Diffusion barrier; Oxidation; Cemented carbide; Glass molding

Preparation and properties of zinc blende and orthorhombic SnS films by chemical bath deposition by Chao Gao; Honglie Shen; Lei Sun (pp. 6750-6755).

► A novel chelating reagent ammonium citrate was applied in the chemical bath deposition of SnS films and the results were presented. ► Zinc blende and orthorhombic structured SnS films can be obtained by changing the pH values and the temperature of the deposition system. ► The mechanism for the preparation of SnS films with different structures was discussed. ► The SnS films with different structures are all compact and continuous, and the resistivities of the SnS films are lower than the ever reported values.SnS (stannous sulfide) films were prepared by chemical bath deposition in which a novel chelating reagent ammonium citrate was used. The film has a zinc blende structure or an orthorhombic structure which is determined by the pH value and the temperature of the deposition solution. The reason for this result is considered to be that SnS films prepared under different conditions have different deposition mechanisms (ion-by-ion mechanism for the zinc blende structured SnS and hydroxide cluster mechanism for the orthorhombic structured SnS). The prepared SnS films are homogeneous and well adhered. SEM images show that the SnS films with different structures have different surface morphologies. Electrical test shows that the resistivity of the films is as low as 420Ωcm and 3300Ωcm for orthorhombic and zinc blende SnS films, respectively, which are much lower than the ever reported values. Persistent photoconductivity (PPC) phenomena are observed for both the films with zinc blende and orthorhombic structures by photo-current responses measurement. The optical bandgaps of the SnS films are determined to be 1.75eV and 1.15eV for zinc blende structure and orthorhombic structure, respectively.

Keywords: SnS; Chemical bath deposition; Crystal structure; Optical and electrical properties

Effect of different annealing methods on ferroelectric properties of 0.95Pb(Sc_0.5Ta_0.5)O₃–0.05PbTiO₃ thin films by Xuedong Li; Hongli Guo; Hong Liu; Dingquan Xiao; Jianguo Zhu (pp. 6756-6760).

► The films were fabricated by radio frequency magnetron sputtering technique. ► A novel two-steps rapid thermal annealing approach was demonstrated. ► Microstructure plays an important role in enhanced ferroelectric properties. ► Two-steps rapid thermal annealing could be potential for ferroelectric films.0.95Pb(Sc_0.5Ta_0.5)O₃–0.05PbTiO₃ thin films were prepared on LaNiO₃/SiO₂/Si substrate by radio frequency magnetron sputtering, and the films were annealed subsequently with repeated many times by two approaches: normal one-step rapid thermal annealing and innovative two-steps rapid thermal annealing. X-ray diffraction demonstrates that all the films were preferred (100) oriented and an appropriate repeat of annealing process can enhance perovskite phase of the films. Scanning electron microscopy suggests that the films treated by two-steps rapid thermal annealing show crack-free, uniform size grains and dense microstructure. Measurement of remnant polarization and leakage current dependence of electric field confirms that the films treated by two-steps rapid thermal annealing exhibit better ferroelectric properties than the films treated by one-steps rapid thermal annealing. The results reveal that microstructure plays an important role in enhanced ferroelectric properties of the 0.95Pb(Sc_0.5Ta_0.5)O₃–0.05PbTiO₃ thin films.

Keywords: 0.95Pb(Sc; _0.5; Ta; _0.5; )O; ₃; –0.05PbTiO; ₃; thin films; Radio frequency magnetron sputtering; Two-steps rapid thermal annealing; Ferroelectric properties

High temperature stability of nanocrystalline anatase powders prepared by chemical vapour synthesis under varying process parameters by Md. Imteyaz Ahmad; Claudia Fasel; Thomas Mayer; S.S. Bhattacharya; Horst Hahn (pp. 6761-6767).

► Nanocrystalline titania synthesised by chemical vapour synthesis process under varying gas flow rates. ► With increasing O₂/He flow rate ratio the chemical by product shifted from C₃H₆ to CO₂, which resulted in carbon getting into the structure of Anatase. ► Carbon incorporation into anatase enhanced its stability to higher temperatures.Systematic variation in the high temperature stability of nanocrystalline anatase powders prepared by chemical vapour synthesis (CVS) using titanium (IV) isopropoxide under varying flow rates of oxygen and helium was obtained by progressively shifting the decomposition product from C₃H₆ to CO₂. The as-synthesised powders were characterised by high temperature X-ray diffraction (HTXRD), simultaneous thermo-gravimetric analyses (STA), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). It was observed that the anatase to rutile transformation temperature progressively increased for samples synthesised at higher O₂/He flow rate ratios. The improved anatase stability was attributed to the presence of incorporated carbon within the titania structure and confirmed by a high temperature carbon desorption peak.

Keywords: Phase transition; Anatase; Chemical vapour synthesis; High temperature X-ray diffraction

Effect of oligoethylene glycol moieties in porous silicon surface functionalisation on protein adsorption and cell attachment by Martin J. Sweetman; Frances J. Harding; Sean D. Graney; Nicolas H. Voelcker (pp. 6768-6774).

► Synthesis and characterisation of novel alkene linkers for pSi functionalisation. ► Covalent immobilisation of protein to functionalised pSi has been demonstrated. ► The presence of OEG restricted BSA adsorption onto functional surfaces. ► Covalently immobilised fibronectin enhanced cell adhesion on functional surfaces.We report on the synthesis of two carboxy-functional alkene compounds as modifiers of porous silicon (pSi) surface chemistry by means of thermal hydrosilylation. Both alkene compounds have hydrophobic, aliphatic carbon segments, with terminal carboxylic acid functionality appended through a thioether linkage. In one of the alkene linkers, we incorporated a short oligoethylene glycol (OEG) moiety to explore its low-fouling properties when attached to porous silicon. We examined surface stability of the surface-modified porous silicon in aqueous milieu. Albumin and fibronectin were adsorbed and, using carbodiimide chemistry, covalently immobilised to linker-modified porous silicon, and the propensity for mammalian cells to attach to these surfaces investigated. Surface chemistry was characterised by infrared spectroscopy and the stability of porous silicon in an aqueous milieu was investigated by interferometric reflectance spectroscopy (IRS). Surfaces functionalised with the alkene linker containing OEG displayed greater resistance to the adsorption of albumin. This linker also facilitated higher levels of covalent protein immobilisation to the functionalised pSi surface. Higher levels of cell attachment were observed on pSi surfaces with fibronectin covalently immobilised onto the OEG linker, than for fibronectin covalently immobilised on the non-OEG linker.

Keywords: Porous silicon; Biomaterial; Hydrosilylation; Oligoethylene glycol; Cell culture

Ripple topography on thin ZnO films by grazing and oblique incidence ion sputtering by S. Bhattacharjee; P. Karmakar; A.K. Sinha; A. Charkrabarti (pp. 6775-6778).

► Fabrication of ZnO nanostructures by low energy ion beams. ► Orientation and size control of ion induced ZnO nano ripples. ► Basic formation mechanisms of parallel nano-ripple structures at grazing incidence ion bombardment.We have investigated the formation and growth of nano sized ripple topography on ZnO thin films by 10keV O¹⁺ bombardment at impact angles of 80° and 60°, varying the ion fluence from 5×10¹⁶ to 1×10¹⁸ions/cm². At 80° the ripples are oriented along the ion beam direction whereas at 60° it is perpendicular to the ion beam direction. The developed ion induced structures are characterized by atomic force microscopy (AFM) and the alignment, variation of rms roughness, wavelength and correlation length of the structures are discussed with the existing model and basic concept of ion surface interaction.

Keywords: PACS; 61.80.Jh; 81.16.−c; 79.20.Rf; 81.16.Rf; 79.20.ApSputtering; Ripple; Grazing incidence; ZnO

Synthesis and characterization of Cu²⁺ doped ZnS nanoparticles using TOPO and SHMP as capping agents by M. Kuppayee; G.K. Vanathi Nachiyar; V. Ramasamy (pp. 6779-6786).

► Enhanced PL emission was obtained using surfactants. ► Optimum concentration of impurity ions was determined by PL emission. ► Through the surfactants, the surface defect of the nanoparticles was reduced. ► Quantum confinement effect was observed for ZnS:Cu nanoparticles.Undoped and Cu²⁺ doped (0.2–0.8%) ZnS nanoparticles have been synthesized through chemical precipitation method. Tri-n-octylphosphine oxide (TOPO) and sodium hexametaphosphate (SHMP) were used as capping agents. The synthesized nanoparticles have been analyzed using X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectrometer (FT-IR), UV–vis spectrometer, photoluminescence (PL) and thermo gravimetric-differential scanning calorimetry (TG-DTA) analysis. The size of the particles is found to be 4–6nm range. Photoluminescence spectra were recorded for ZnS:Cu²⁺ under the excitation wavelength of 320nm. The prepared Cu²⁺-doped sample shows efficient PL emission in 470–525nm region. The capped ZnS:Cu emission intensity is enhanced than the uncapped particles. The doping ions were identified by electron spin resonance (ESR) spectrometer. The phase changes were observed in different temperatures.

Keywords: ZnS:Cu; ²⁺; nanoparticles; Band gap; Semiconductor; Luminescence; X-ray diffraction; TEM

Effect of surface nanocrystallization induced by fast multiple rotation rolling on hardness and corrosion behavior of 316L stainless steel by Pengfei Chui; Kangning Sun; Chang Sun; Xiuqing Yang; Ting Shan (pp. 6787-6791).

► Effect of Surface nanocrystallization on 316L stainless steel. ► A novel and efficient surface nanocrystallization technique was developed. ► Microhardness remarkably increases from 190 to 530HV. ► Corrosion resistance deteriorated after treatment. ► Possible reasons leading to the decrease in corrosion resistance were discussed.A nanostructured layer was fabricated by using fast multiple rotation rolling (FMRR) on the surface of 316L stainless steel. The microstructure in the surface was characterized by transmission electron microscopy and X-ray diffraction. The effects of FMRR on the microhardness, surface roughness and corrosion behavior of the stainless steel were investigated by microhardness measurements, surface roughness measurements, potentiodynamic polarization curves and pitting corrosion tests. The surface morphologies of pitting corrosion specimens were characterized by scanning electron microscopy. The results show that FMRR can cause surface nanocrystallization with the grain size ranges from 6 to 24nm in the top surface layer of the sample. The microhardness of FMRR specimen in the top surface layer remarkably increases from 190 to 530HV. However, the surface roughness slightly rises after FMRR treatment. The potentiodynamic polarization curves and pitting corrosion tests indicated that the FMRR treated 316L stainless steel with a surface nanocrystallized layer reduced the corrosion resistance in a 3.5% NaCl solution and enhanced the pitting corrosion rate in a FeCl₃ solution. Possible reasons leading to the decrease in corrosion resistance were discussed.

Keywords: Surface nanocrystallization; Fast multiple rotation rolling; 316L stainless steel; Microhardness; Surface roughness; Corrosion resistance

Investigation of the (√3×√3)R30°-Cu₂Si/Cu(111) surface alloy using DFT by I.G. Shuttleworth (pp. 6792-6798).

► Evident and surprising similarities between the Si–Cu interaction for each of these phases, despite differences in the surface-2nd layer registry and proven Si–Cu interactions between these two layers. ► Si states in these systems do not undergo significant hybridization, and the Si–Cu bonds lack directionality and form either covalent or metallic states. ► Significant distortions in the 2nd layer Cu 3d orbitals which are exactly compensated by bond length differences between the surface and 2nd layer, suggesting the masking of these effects in a simple work function analysis. ► Preliminary energetic analysis suggestive that boundary and mass transport effects dominate the formation of the stable mixed phase surface.The electronic structure of the FCC, HCP and 2-fold bridge phases of the (√3×√3)R30°-Cu₂Si/Cu(111) surface alloy have been investigated using LCAO-DFT. Analysis of the total electron density, partial density-of-states (PDOS) and crystal orbital overlap population (COOP) curves for the system have shown a surprising similarity between the intra- and inter-layer Si–Cu bond for each phase. Low hybridization between the Si 3s and 3p orbitals results in a low directionality of the Si–Cu bond within each of phase. The Si 3s orbitals are shown to form covalent bonds with their surrounding Cu atoms whereas the Si 3p and 3d orbitals are shown to form combinations of covalent and metallic bonds. The Si–Cu interaction is shown clearly to extend to the second layer of the alloy in deference to previous studies of Si/Cu alloys.

Keywords: Cu; ₂; Si; Cu(1; 1; 1); Alloy; DFT; GGA; Crystal orbital overlap population; COOP; Partial density of states; PDOS

The preparation and antibacterial effects of dopa-cotton/AgNPs by Hong Xu; Xue Shi; Hui Ma; Yihang Lv; Linping Zhang; Zhiping Mao (pp. 6799-6803).

► The cotton fabric was coated with a thin adherent polydopamine membrane. ► Ag⁺ was in situ reduced to Ag⁰ nanoparticles and carried out on the polydopamine. ► Dopamine as a kind of biomolecules was utilized as the binding agent and reductant. ► The cotton fabrics with silver nanoparticles showed durable antibacterial activity.Silver nanoparticles (AgNPs) have been known to have powerful antibacterial activity. In this paper, in situ generation of AgNPs on the surface of dopamine modified cotton fabrics (dopa-cotton/AgNPs) in aqueous solution under room temperature is presented. X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscope (FE-SEM) were used to analyze the surface chemical composition and the morphology of the modified cotton fabrics, respectively. The results indicated that the surface of cotton fabrics was successfully coated with polydopamine and AgNPs. The cotton fabrics with AgNPs showed durable antibacterial activity.

Keywords: Dopamine; Silver nanoparticles; Antibacterial activity

Correlation of sp³ and sp² fraction of carbon with electrical, optical and nano-mechanical properties of argon-diluted diamond-like carbon films by Neeraj Dwivedi; Sushil Kumar; H.K. Malik; Govind; C.M.S. Rauthan; O.S. Panwar (pp. 6804-6810).

▶ XPS was used to estimate % sp³ and sp² fractions of carbon. ▶ Estimated sp³ fraction has been correlated with nano-mechanical properties. ▶ Calculated sp² fraction has been correlated with electrical and optical properties. ▶ In addition to hardness ( H) and elastic modulus (E) several other mechanical parameters such as plastic resistance parameter ( H/E), elastic recovery (ER), ratio of residual displacement after load removal with displacement at maximum load ( d_res/ d_max) and plastic deformation energy ( U_r) in Ar-DLC films have also been estimated.In the present work the correlation of electrical, optical and nano-mechanical properties of argon-diluted diamond-like carbon (Ar-DLC) thin films with sp³ and sp² fractions of carbon have been explored. These Ar-DLC thin films have been deposited, under varying C₂H₂ gas pressures from 25 to 75mTorr, by radio frequency-plasma enhanced chemical vapor deposition technique. X-ray photoelectron spectroscopy studies are performed to estimate the sp³ and sp² fractions of carbon by deconvoluting C 1s core level spectra. Various electrical, optical and nano-mechanical parameters such as conductivity, I– V characteristics, optical band gap, stress, hardness, elastic modulus, plastic resistance parameter, elastic recovery and plastic deformation energy have been estimated and then correlated with calculated sp³ and sp² fractions of carbon and sp³/sp² ratios. Observed tremendous electrical, optical and nano-mechanical properties in Ar-DLC films deposited under high base pressure conditions made it a cost effective material for not only hard and protective coating applications but also for electronic and optoelectronic applications.

Keywords: XPS; Electrical properties; Mechanical properties; Optical properties

Directional motion of water drop on ratchet-like superhydrophobic surfaces by Xianliang Sheng; Jihua Zhang (pp. 6811-6816).

Display Omitted► Ratchet-like superhydrophobic surfaces were fabricated. ► One-dimensional anisotropic wettabilities are observed on such ratchet-like surfaces. ► Directional differences of wettabilities are tailored by the ratchet-like structures. ► Low retention and ratchet-like structures are keys for the directional wettabilities.In this article, directional movements of drops on the ratchet-like superhydrophobic surfaces were observed. High-speed CCD images showed the caterpillar-like crawl of a drop on the inclined superhydrophobic surfaces as it rolled along the ridge of ratchet. In contrast, along the opposite direction, the movement of the drop only depended on the end of triple phase contact line while the front of contact line was pinned. The sliding angle (SA) measurements indicated that the ratchet-like superhydrophobic surfaces had directional drop retention traits. Moreover, the reduction of the rise angle ω₁, the height d of the ratchet's ridge and the volume V of the drop can greatly enhance the directional difference of drop retention on the ratchet-like superhydrophobic surfaces. Therefore, it was concluded that the superhydrophobicity and the periodic ratchet-like microstructures were the keys to the directional drop sliding at one-dimensional level. We believe that these findings would be helpful to better understand the ratchet-like effect on the superhydrophobic surfaces and guide some novel engineering applications.

Keywords: Ratchet; Superhydrophobic; Directional retention and wettability

Photosensitive sol–gel preparation and direct micro-patterning of c-oriented ZnO film by Chen Yuanqing; Yan Fuxue; Zhao Gaoyang; Wang Zhezhe (pp. 6817-6820).

► A photosensitive sol–gel method is employed to prepare ZnO film. The unique of this method lies in the fact that the obtained sol and gel is sensitive to the UV light. ► Transparent and c-oriented ZnO film can be obtained on glass through an optimal heat treatment process. ► Using the photosensitive sol–gel method combined with UV-exposure and leaching, patterned ZnO film can be obtained. ► This kind of patterning method is simple and low-cost, without degrading the film properties.Using zinc acetate as the raw material, isopropanol as the solvent, and monoethanolamine as the stabilizer, photosensitive ZnO sol is prepared by chemical modification with the acetylacetone. Chelate rings of acetylacetone with zinc ions are formed in the ZnO sol and its corresponding gel films. Irradiation of the gel film by a UV lamp in air leads to the decomposition of the chelate ring. Using the photosensitivity of the gel films, ZnO gel patterns can be obtained by selective irradiation followed by leaching in organic solvents. After the patterned ZnO gel film is preheated at 500°C, and fired at 600°C, c-oriented ZnO patterned films are obtained.

Keywords: Key words; Sol–gel; Zinc oxide; Film; Micro-pattern

Photocatalytic performance of silver TiO₂: Role of electronic energy levels by L. Gomathi Devi; K. Mohan Reddy (pp. 6821-6828).

. Decrease in band-gap in DP25 and Ag-DP25 was observed due to the carbide ion substitution for oxide ion in TiO₂ silver metal deposits and unintentional incorporation of the carbon shows the beneficial effect by specific mechanism in the photocatalytic degradation of Congo Red.Display Omitted► The effect of metallization of semiconductor particles is explored extensively. But the real involvement of C_1s level in Degussa P25 and Ag deposited Degussa P25 has not been explored. ► The beneficial effects of silver deposit and the incorporated C_1s levels for the trapping of electrons and as effective adsorbent site to concentrate the pollutant molecules around the TiO₂ particles is explained in detail. ► The incorporated carbon can possibly indirectly prevent recombination of e⁻ - h⁺ pairs. ► The beneficial effect of C_1s level and silver metal deposit is explained along with the surface Plasmon adsorption which makes the catalyst more efficient.Nano-sized silver deposits on the surface of Degussa P25 TiO₂ (Ag-DP25) particles act as sites of electron accumulation where the reduction of adsorbed species takes place. Electrons can be transferred from Degussa P25 TiO₂ (DP25) to Ag particles because of the difference in the work functions of the two materials. The efficiency of the electron transfer depends on the size and the distribution of metal deposits. A significant photocatalytic oxidation enhancement by metal deposit will only be observed if the metal deposits play a more dominant role than just increasing the life time of charge carriers. The properties of metal deposits like, loaded amount, oxidation state of the deposit and its size will influence the performance. Further, a decrease in band-gap in DP25 and Ag-DP25 was observed due to the carbide ion substitution for the oxide ion in TiO₂. Such unintentional carbon incorporation is expected mostly in combustion synthesized materials. Silver metal deposits and unintentional incorporation of the carbon shows the beneficial effect by specific mechanism in the photocatalytic degradation of Congo Red (CR).

Keywords: Silver metallized TiO; ₂; Degussa P25; Inter band transition; Congo Red; Sol–gel TiO; ₂

Imprinting the nanostructures on the high refractive index semiconductor glass by M. Silvennoinen; K. Paivasaari; J.J.J. Kaakkunen; V.K. Tikhomirov; A. Lehmuskero; P. Vahimaa; V.V. Moshchalkov (pp. 6829-6832).

► High aspect ratio nano-replication onto the surface of glass and of semiconductor. ► Nanoimprinting less than 100nm pitch structures on the surface of glass and of semiconductor. ► Nano-replicated high refractive index semiconductor glass for application in photonic crystals, sub-microelectronic chips and moth eye structures.The centimeter range one- and two-dimensional nanostructures of 70nm pitch have been imprinted by hot pressing with a quartz, silicon or nickel mold, at 240°C, onto the surface of Ge₂₀As₂₀Se₁₄Te₄₆ semiconductor glass. Excellent glass stability of this glass allows multiple re-pressing of the nano-structures. With increasing the Te/Se ratio in the glass formula, the refractive index reaches a value of 3.5 with an option of free electron absorption at elevated temperatures pointing out the use of such nanostructures in submicron and micron scale electronic devices/chips, moth eye structures and photonic crystals.

Keywords: (160.2750) Glass and other amorphous materials; (160.4236) Nanomaterials; (220.4000) Microstructure fabrication

Structural and optical properties of YSZ thin films grown by PLD technique by S.K. Pandey; O.P. Thakur; R. Raman; Anshu Goyal; Amita Gupta (pp. 6833-6836).

► Yttria stabilized zirconia (YSZ) thin films were grown by pulsed laser deposition (PLD) technique. ► The films were in situ crystallised at different substrate temperatures ( T_s=400°C, 500°C and 600°C). ► XRD analysis shows single phase fluorite films (YSZ has a fluorite crystallographic structure) with preferred orientation along 〈111〉. ► The surface roughness of the films were nano sized that increases further with the increase of deposition temperatures. ► An optical band gap of ∼5.7eV is in agreement with the reported values.We report on the structural and optical properties of yttria stabilized zirconia (YSZ) thin films grown by pulsed laser deposition (PLD) technique and in situ crystallized at different substrate temperatures ( T_s=400°C, 500°C and 600°C). Yttria-stabilized zirconia target of ∼1in. diameter (∼95% density) was fabricated by solid state reaction method for thin film deposition by PLD. The YSZ thin films were grown on an optically polished quartz substrates and the deposition time was 30min for all the films. XRD analysis shows cubic crystalline phase of YSZ films with preferred orientation along 〈111〉. The surface roughness was determined by AFM for the films deposited at different substrate temperatures. The nano-sized surface roughness is found to increase with the increase of deposition temperatures. For the optical analysis, a UV–vis–NIR spectrophotometer was used and the optical band gap of ∼5.7eV was calculated from transmittance curves.

Keywords: Thin films; YSZ; Laser ablation; Band gap

Preparation and characteristics of three-layer YSZ–(YSZ/Al₂O₃)–YSZ TBCs by C. Ren; Y.D. He; D.R. Wang (pp. 6837-6842).

▶ Three-layer YSZ–(YSZ/Al₂O₃)–YSZ TBCs were fabricated by using composite sol-gel slurries and pressure filtration microwave sintering processes. ▶ The oxidation resistance can be improved by designing the structure of YSZ/Al₂O₃ composite layer due to its sealing effect. ▶ The thermal stresses can be reduced by the impeded propagation of cracks at layer/layer interfaces and thermal expansion match. ▶ This three-layer ceramic coating can be further study to meet the desirable criterion for an application as a new kind of TBC.Novel three-layer YSZ–(YSZ/Al₂O₃)–YSZ (6wt.% Y₂O₃ partially stabilized ZrO₂) thermal barrier coatings (TBCs) were successfully prepared on Ni-based superalloy substrate using composite sol–gel and pressure filtration microwave sintering (PFMS) techniques. The coatings were evaluated for the cyclic oxidation resistance, thermal barrier effect and the presences of phases and microstructures. FE-SEM results indicate that the coatings were dense and crack-free. The coatings maintained their structural integrity when they were exposed at 1100 for 100h. They exhibited superior oxidation resistance, spallation resistance and thermal insulation property compared with single-layer YSZ coatings. Moreover, the detailed mechanisms were discussed in order to understand the improved performance of the three-layer TBCs.

Keywords: Laminated TBCs; Composite sol–gel; Cyclic oxidation resistance; Spallation resistance; Thermal barrier effect

Hydrogen-free spray pyrolysis chemical vapor deposition method for the carbon nanotube growth: Parametric studies by Mihnea Ioan Ionescu; Yong Zhang; Ruying Li; Xueliang Sun; Hakima Abou-Rachid; Louis-Simon Lussier (pp. 6843-6849).

► Spray pyrolysis CVD in the absence of hydrogen at low carrier gas flow rates. ► CNTs on semiconducting silicon wafer, carbon microfibers, and stainless steel plates. ► CNT average length and diameter decrease with temperature and injection speed. ► Catalyst concentration influences the bimodal diameter distribution of CNTs.Spray pyrolysis chemical vapor deposition (CVD) in the absence of hydrogen at low carrier gas flow rates has been used for the growth of carbon nanotubes (CNTs). A parametric study of the carbon nanotube growth has been conducted by optimizing various parameters such as temperature, injection speed, precursor volume, and catalyst concentration. Experimental observations and characterizations reveal that the growth rate, size and quality of the carbon nanotubes are significantly dependent on the reaction parameters. Scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy techniques were employed to characterize the morphology, structure and crystallinity of the carbon nanotubes. The synthesis process can be applied to both semiconducting silicon wafer and conducting substrates such as carbon microfibers and stainless steel plates. This approach promises great potential in building various nanodevices with different electron conducting requirements. In addition, the absence of hydrogen as a carrier gas and the relatively low synthesis temperature (typically 750°C) qualify the spray pyrolysis CVD method as a safe and easy way to scale up the CNT growth, which is applicable in industrial production.

Keywords: Carbon nanotubes; Chemical vapor deposition; Spray pyrolysis

Synthesis of ultrafine single crystals and nanostructured coatings of indium oxide from solution precursor by Nagaswetha Pentyala; Ramesh K. Guduru; Elizabeth M. Shnerpunas; Pravansu S. Mohanty (pp. 6850-6857).

► Simple calcination process to synthesize single crystals of In₂O₃. ► Study of thermal decomposition and phase transformations of InCl₃ into In₂O₃. ► Solution precursor plasma spray route to produce large scale coatings at fast rates.Indium oxide (In₂O₃) has been widely used in sensors, solar cells and microelectronics. There are several techniques available for making In₂O₃ such as vapor, electrochemical and atomic layer deposition, which are not only expensive but also time consuming processes. In this study, an inexpensive and straightforward synthesis approach is being presented to make micron/submicron size single crystals as well as nanostructured adherent coatings of In₂O₃ using Indium Chloride (InCl₃) powders and InCl₃ solution precursor. Both the powders and the solution precursor were calcined in a furnace to obtain the crystals; however, the liquid precursor was also treated by a DC plasma jet to obtain the nanostructured coatings. The phase transformations during thermal decomposition of InCl₃ powders and solution precursor were investigated via differential scanning calorimetry studies. The phase structure and crystallinity of the crystals and coatings were confirmed by X-ray diffraction. Microstructural characterization of the crystals and coatings was done by scanning electron microscopy, transmission electron microscopy and atomic force microscopy techniques. Size of the crystals was observed to be dependent on the heating schemes adapted during calcination. Solution precursor plasma sprayed In₂O₃ coatings showed porosity and ultrafine particulates with grain size ranging between 10 and 75nm. Resistivity was determined to be ∼0.553±0.337kΩcm. Optical transmittance of In₂O₃ coatings was ∼60–78% in the visible region and it was observed to decrease with increasing the number passes or the thickness of the coatings. Based on the optical transmission data, direct band gap of 3.57eV was determined.

Keywords: Indium oxide; Plasma spray; Solution precursor; Single crystals; Resistivity; Optical properties; Band gap

Poly(methylmethacrylate) as immobilization matrix for europium β-diketonates—Morphology and fluorescent properties by J. Zaharieva; M. Milanova; D. Todorovsky (pp. 6858-6866).

► Embedded in poly(methylmethacrylate) Eu-β–diketonates preserve the emission spectra. ► Using polymer solution as films production starting material is to be preferred. ► The films morphology depends on the ligands, matrix production/deposition methods.The properties of composites prepared by the immobilization of Eu(III) complexes with dibenzoylmethane and thenoyltrifluoracetone in poly(methylmethacrylate) are studied. The matrices are produced by polymerization of the monomer or by using chloroform solution of the polymer. The films produced from polymerized monomer by dip-coating or spray-pyrolysis are dense and uniform and show a tendency to form a chain structure. Uniform films, with separate sharp “peaks” or pores, 20–80nm in diameter and grains with order size of 20nm are formed from poly(methylmethacrylate) chloroform solution. The morphology depends on the nature of ligands and co-ligands, the matrix production method and the deposition method. Embedding of the complexes does not significantly influence the emission spectra of the produced films and membranes.

Keywords: Immobilization matrices; Poly(methylmethacrylate); Eu complexes; AFM; SEM

Scattering effects and damping of electrons in Pt(111) and Cu(111) by I. Morawski; M. Nowicki (pp. 6867-6872).

► In this study we use the DEPES method to reveal the crystalline structure of Cu(111) and Pt(111), as well as to investigate the mechanism of electron scattering along the [111] direction and damping of electrons in crystalline samples. ► Both experimental and theoretical approaches were used. The later is based on the multiple scattering (MS) formalism. ► We conclude that the characteristic pattern observed along the [111] direction originate from the so called ring focusing effect as a consequence of the collective scattering of primary electrons by atoms located around the three fold symmetry axis. ► Different relative intensity values obtained in experimental and theoretical DEPES distributions are rationalised by the inelastic mean free path, which can have an anisotropic character.In this work an analysis of experimental and theoretical data associated with the scattering and attenuation of electrons in the Pt(111) and Cu(111) crystalline samples is presented. The information about the crystalline structure of the first few atomic layers was obtained by the directional elastic peak electron spectroscopy (DEPES) at the primary electron beam energies E_p from 1.5keV to 2.0keV. The comparison of the experimental and theoretical DEPES distributions indicates a qualitative agreement between experiment and theory. The relative signal values associated with the intensity maxima were found to be different. The latter effect suggest that the electron attenuation in the crystalline samples can have an anisotropic character. A qualitative analysis of the characteristic pattern around the [111] direction concerning the calculation of the scattering factors was performed. The collective scattering of electrons by atoms located around the threefold symmetry axis resulting in the so called ring focusing effect is discussed.

Keywords: Electron scattering; Attenuation; Copper; Platinum; Inelastic mean free path; DEPES

Synthesis and characteristics of natural zeolite supported Fe³⁺-TiO₂ photocatalysts by Cheng Wang; Huisheng Shi; Yan Li (pp. 6873-6877).

► Natural zeolite supported Fe³⁺-TiO₂ photocatalysts were synthesized. ► Zeolite restrained the growth of crystallite sizes. ► The iron ions could diffuse into TiO₂ lattice to the form Fe–O–Ti bond. ► Photocatalytic activity of the samples could be enhanced as iron ions were doped.Natural zeolite supported Fe³⁺-TiO₂ photocatalysts were synthesized for the sake of improving the recovery and photocatalytic efficiency of TiO₂. The as-prepared materials were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflection spectroscopy (UV–vis DRS), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). Methyl orange was used to estimate the photocatalytic activity of the samples. The results showed that zeolite inhibited the growth of TiO₂ crystallite sizes. The Fe³⁺ concentration played an important role on the microstructure and photocatalytic activity of the samples. The iron ions could diffuse into TiO₂ lattice to the form Fe–O–Ti bond and gave TiO₂ the capacity to absorb light at lower energy levels. The photocatalytic activity of the samples could be enhanced as appropriate dosages of Fe³⁺ were doped.

Keywords: Zeolite; Fe; ³⁺; TiO; ₂; Photocatalyst

Density functional theory study of selenium adsorption on Fe(110) by E.A. González; P.V. Jasen; M. Sandoval; P. Bechthold; A. Juan; B. Setina Batic; Monika Jenko (pp. 6878-6883).

► Using periodic DFT calculations we found that the most favourable adsorption sites of Se on Fe(110) is a long bridge site (at very low coverage) with a short bridge and atop sites being less favourable. ► To the best of our knowledge there is not previous DFT calculations for adsorbed Se on iron surfaces. ► Se adsorption causes the substrate to reconstruct and relax including the 2nd and 3rd neighbours and the subsurface layer. ► The Fe–Se bonding interaction makes the Fe–Fe surfaces bond weaker in agreement with the observed reconstruction. ► This surface reconstruction and the changes in overlap populations could be one of the reasons of reconstruction at a microscale.The adsorption of atomic Se on a Fe(110) surface is examined using the density functional theory (DFT). Selenium is adsorbed in high-symmetry adsorption sites: the -short and long-bridge, and atop sites at 1/2, 1/4, and 1 monolayer (ML) coverages. The long bridge (LB) site is found to be the most stable, followed by the short bridge (SB) and top sites (T). The following overlayer structures were examined, p(2×2), c(2×2), and p(1×1), which correspond to 1/4 ML, 1/2 ML, and 1 ML respectively. Adsorption energy is −5.23eV at 1/4 ML. Se adsorption results in surface reconstruction, being more extensive for adsorption in the long bridge site at 1/2 ML, with vertical displacements between +8.63 and −6.69% -with regard to the original Fe position-, affecting the 1st and 2nd neighbours. The largest displacement in x or y-directions was determined to be 0.011, 0.030, and 0.021Å for atop and bridge sites. Comparisons between Se-adsorbed and pure Fe surfaces revealed reductions in the magnetic moments of surface-layer Fe atoms in the vicinity of the Se. At the long bridge site, the presence of Se causes a decrease in the surface Fe d-orbital density of states between 4 and 5eV below Fermi level. The density of states present a contribution of Se states at −3.1eV and −12.9eV. stabilized after adsorption. The Fe–Fe overlap population decrease and a Fe–Se bond are formed at the expense of the metallic bond.

Keywords: DFT; Adsorption; Selenium; Fe(1; 1; 0); Electronic structure

Theoretical and experimental research on spectral performance and laser induced damage of Brewster's thin film polarizers by Meiping Zhu; Kui Yi; Zhengxiu Fan; Jianda Shao (pp. 6884-6888).

► Four Brewster's angle thin-film polarizers are prepared. ► Broad polarizing bandwidth and high extinction ratio are achieved by optimized design. ► Electric field distribution influences the laser induced damage threshold greatly.Polarizers respectively with broad polarizing region bandwidth, large layer thickness error tolerance and high extinction ratio are designed and prepared. Transmittance spectra of the prepared samples are measured at Brewster's angle, and the results show that different requirements can be fulfilled by optimized designs. Spectral performance of designs with higher layer thickness error tolerance coincides better with the theoretical spectra. Laser induced damage threshold of the prepared samples are evaluated. Electric field distribution, defect, film absorption, and damage morphology are investigated, and the results indicate that electric field distribution in high index layers is the main reason that causes the difference of laser induced damage threshold. For both p polarized and s polarized light, the lower the electric field peak value and the farther the layer, which has the strongest electric field away from air, the higher the laser induced damage threshold.

Keywords: Polarizer; Polarizing region bandwidth; Laser induced damage threshold; Electric field distribution

Tannic acid assisted one step synthesis route for stable colloidal dispersion of nickel nanostructures by Anamika Dutta; Swapan K. Dolui (pp. 6889-6896).

► Highly stable colloidal dispersion of Ni nanostructures in ethylene glycol is achieved from NiCl₂·6H₂O by using tannic acid (TA) as reductant. ►The process does not require additional capping agent. Because TA acts as both capping and reducing agent. ► The morphology of Ni nanostructures is influenced by the concentration of TA.We report here a one step synthesis route for highly stable colloidal dispersion of nickel (Ni) nanostructures in ethylene glycol (EG). tannic acid (TA), a naturally occurring molecule was used as reducing as well as capping agent. Different instrumental techniques were used to characterize the end product. It has been found that the particles are pure crystalline nickel with a face-centred-cubic (fcc) structure which are uniformly distributed throughout the surface of Ni–TA complex hybrid nanostructures resulting flower-like morphology. The synthesized nanoparticles are remarkably stable for several months. It is supposed that the TA-capped Ni nanoparticles with significantly increased stability and dispersibility could be used as a novel nanoscale material in various technological applications.

Keywords: Nickel nanostructures; Tannic acid; Characterization; Stable colloidal dispersion; Capping agent

Effect of cobalt doping and annealing on properties of titania thin films prepared by sol–gel process by R. Pärna; U. Joost; E. Nõmmiste; T. Käämbre; A. Kikas; I. Kuusik; M. Hirsimäki; I. Kink; V. Kisand (pp. 6897-6907).

► Cobalt in the cobalt doped TiO₂ thin films was mainly in Co²⁺ oxidation state. ► CoTiO₃ was discovered in the cobalt doped TiO₂ films after annealing above 650°C. ► During annealing cobalt compounds segregate to the surface of samples. ► EDX analysis showed that “islands” of cobalt compounds are formed in the sample. ► Cobalt doping red-shifted the fundamental absorption edge compared to virgin titania.Undoped and cobalt doped titania (TiO₂) thin films have been prepared on Si(100) monocrystal and quartz substrate using the sol–gel deposition method and annealed in air at 450, 550, 650, 750, 850, 950 and 1050°C. Several experimental techniques (AFM, XRD, Raman spectroscopy, XRR, EDX, XPS, XAS, UV–VIS spectroscopy) have been used to characterize these films. Further more the degree of light induced hydrophilicity was estimated by measuring the contact angle of a water droplet on the film. Increase of the annealing temperature and in smaller degree also cobalt doping predispose titania crystallite growth. The rutile phase was detected at lower temperatures in the cobalt doped films than in the undoped titania films. Cobalt in the cobalt doped TiO₂ was seen to be in Co²⁺ oxidation state, mainly in CoTiO₃ phase when films were annealed at temperatures higher than 650°C. Cobalt compounds segregated into the sub-surface region and to the surface of the titania, where they formed islands. Cobalt doping red-shifted the fundamental absorption edge further into the visible range, however it did not enhance the light induced hydrophilicity of the thin film surface as compared to the undoped titania thin films.

Keywords: Titanium dioxide; Cobalt; Sol–gel; Thin films; Light induced hydrophilicity

Electrodeposition of zinc oxide/tetrasulfonated copper phthalocyanine hybrid thin film for dye-sensitized solar cell application by Xinze Luo; Lin Xu; Bingbing Xu; Fengyan Li (pp. 6908-6911).

.Display Omitted► Hybrid film of zinc oxide and tetrasulfonated copper phthalocyanine (TSPcCu) was prepared by using constant-current electrodeposition method. ► The nanosheets stack of ZnO leads to a porous surface structure and the TSPcCu was uniformly covered on the surface of ZnO crystallites. ► The TSPcCu plays a significant role in enhancing photovoltaic performance. ► The hybrid film of ZnO/TSPcCu shows a three-fold improvement in energy conversion efficiency than that the only ZnO film.Hybrid film of zinc oxide (ZnO) and tetrasulfonated copper phthalocyanine (TSPcCu) was grown on an indium tin oxide (ITO) glass by one-step cathodic electrodeposition from aqueous mixtures of Zn(NO₃)₂, TSPcCu and KCl. The addition of TSPcCu strongly influences the morphology and crystallographic orientation of the ZnO. The nanosheets stack of ZnO leads to a porous surface structure which is advantageous to further adsorb organic dyes. The photovoltaic properties were investigated by assembling the DSSC device based on both the only ZnO film and the ZnO/TSPcCu hybrid films. Photoelectrochemical analysis revealed that the optimized DSSC device with TSPcCu represented a more than three-fold improvement in power conversion efficiency than the device without TSPcCu. The DSSC based on ZnO/TSPcCu hybrid films demonstrates an open circuit voltage of 0.308V, a short circuit current of 90μAcm⁻², a fill factor of 0.26, and a power conversion efficiency of 0.14%.

Keywords: Zinc oxide; Phthalocyanine; Electrodeposition; Photovoltaic properties

Laser controlled melting of pre-treated zirconia surface by B.S. Yilbas; S.S. Akhtar; C. Karatas (pp. 6912-6918).

► Dense layer formed at surface vicinity composes of fine grains and TiC particles. ► ZrN and ZrC compounds are formed in the surface region. ► Microhardness of laser treated surface increases. ► Residual stress formed at surface vicinity is on the order of −1.6GPa. ► Fracture toughness of laser treated surface reduces to almost 70%.Laser treatment of pre-prepared zirconia surface is carried out. The pre-prepared surface, prior to laser treatment, consists of 50μm carbon film and 7% titanium carbide particles, which are imbedded in the carbon film. The microstructural and morphological changes in the laser treated surface layer are examined using optical and scanning electron microscopes, energy dispersive spectroscopy, and X-ray diffraction. The fracture toughness of the laser treated surface is measured and the residual stress formed at the surface vicinity is determined from the X-ray diffraction technique. It is found that the microhardness of the laser treated surface increased slightly due to the dense layer formed at the surface vicinity. However, the laser treatment process reduces the fracture toughness of the surface due to improved surface hardness and the residual stress formed in the surface vicinity.

Keywords: Laser; Zirconia; Residual stress; Fracture toughness

The effect of heating rate on the structural and electrical properties of sol–gel derived Al-doped ZnO films by Meizhen Gao; Xiaonan Wu; Jing Liu; Wenbao Liu (pp. 6919-6922).

► Effect of heating rate in annealing process for sol–gel-derived AZO film was studied. ► The AZO film with nanorod structure was obtained by a rapid heating rate. ► The AZO nanorods enhance the conductivity of the film significantly. ► We offer a new method to improve the electrical property of sol–gel-derived TCO film.Al-doped ZnO (AZO) films are prepared by sol–gel method with a proper annealing procedure. For the first time, we find that the heating rate which is normally neglected during the post annealing process plays a significant role in improving AZO properties. The AZO film with nanorod structure is obtained by using a rapid heating rate. The AZO nanorods can provide a faster conduction pathway for charge transport due to the high crystal quality and thus enhance the conductivity of the film significantly. After hydrogen treatment, the AZO nanorod film exhibits a minimum resistivity of 1.4×10⁻³Ωcm. This approach to the preparation of AZO nanorods by a simple rapid annealing process may be helpful for the development of sol–gel-derived TCO films.

Keywords: AZO nanorods; Sol–gel method; Heating rate; Electrical property

Synthesis and characterization of porous crystalline SiC thin films prepared by radio frequency reactive magnetron sputtering technique by Afzaal Qamar; Arshad Mahmood; Tuba Sarwar; Nadeem Ahmed (pp. 6923-6927).

► The effect of deposition temperature on structural and optical properties of one of the poly types that is rarely reported in literature i.e. 8H-SiC is represented in this article. ► The details of synthesis of SiC films by reactive magnetron sputtering technique are discussed. ► The structural and optical characterization is focused in detail.Hexagonal SiC thin films have been deposited using radio frequency reactive magnetron sputtering technique by varying the substrate temperature and other deposition conditions. Prior to deposition surface modification of the substrate Si(100) played an important role in deposition of the hexagonal SiC structure. The effect of substrate temperature during deposition on structure, composition and surface morphology of the SiC films has been analyzed using atomic force microscopy, Fourier transform infrared spectroscopy and spectroscopic ellipsometry. X-ray diffraction in conventional θ–2 θ mode and omega scan mode revealed that the deposited films were crystalline having 8H-SiC structure and crystallinity improved with increase of deposition temperature. The bonding order and Si–C composition within the films showed improvement with the increase of deposition temperature. The surface of thin films grew in the shape of globes and columns depending upon deposition temperature. The optical properties also showed improvement with increase of deposition temperature and the results obtained by ellipsometry reinforced the results of other techniques.

Keywords: 8H-SiC; Thin films; Sputtering

Kinetics of electrochemical boriding of low carbon steel by G. Kartal; O.L. Eryilmaz; G. Krumdick; A. Erdemir; S. Timur (pp. 6928-6934).

► The growth kinetics of the boride layers forming on low carbon steel was investigated during electrochemical boriding. ► Very dense and thick boride layers could be formed in a short period of electrochemical boriding (i.e., (19±1)μm thick boride layer at 850°C). ► The systematic studies over a wide range of boriding time and temperature confirmed that the rate of the boride layer formation is strongly dependent on boriding duration and has a parabolic character. ► The activation energy of the borided steel were determined to be (172.75±8.6)kJ/mol which is about 24% lower than that found in the conventional paste boriding process. ► An empirical equation was derived to estimate the thickness of boride layers at different time and temperatures. Additionally the study resulted in a diagram that can be used to predict the thickness of boride layer for a given process time and temperature.In this study, the growth kinetics of the boride layers forming on low carbon steel substrates was investigated during electrochemical boriding which was performed at a constant current density of 200mA/cm² in a borax based electrolyte at temperatures ranging from 1123K to 1273K for periods of 5–120min. After boriding, the presence of both FeB and Fe₂B phases were confirmed by the X-ray diffraction method. Cross-sectional microscopy revealed a very dense and thick morphology for both boride phases. Micro hardness testing of the borided steel samples showed a significant increase in the hardness of the borided surfaces (i.e., up to (1700±200)HV), while the hardness of un-borided steel samples was approximately (200±20)HV. Systematic studies over a wide range of boriding time and temperature confirmed that the rate of the boride layer formation is strongly dependent on boriding duration and has a parabolic character. The activation energy of boride layer growth for electrochemical boriding was determined as (172.75±8.6)kJ/mol.

Keywords: Electrochemical boriding; Growth kinetics; Activation energy; Boride layer thickness

Improvement and mechanism of interfacial adhesion in PBO fiber/bismaleimide composite by oxygen plasma treatment by Dong Liu; Ping Chen; Jujie Mu; Qi Yu; Chun Lu (pp. 6935-6940).

► The dependence of the ILSS on the oxygen plasma processing time was investigated. ► The surface free energy greatly increased, but it was the secondary decisive factor for the improved adhesion. ► The improving mechanisms were investigated by XPS and AFM analysis. ► The composite fracture mode changed after treatment.The improved interfacial adhesion of PBO fiber-reinforced bismaleimide composite by oxygen plasma processing was investigated in this paper. After treatment, the maximum value of interlaminar shear strength was 57.5MPa, with an increase of 28.9%. The oxygen concentration of the fiber surface increased, as did the surface roughness, resulting in improvement of the surface wettability. The cleavage and rearrangement of surface bonds created new functional groups OCO, NCO and NO, thereby activating the fiber surface. And long-time treatment increased the reaction degree of surface groups while destroyed the newly-created physical structures. The enhancement of adhesion relied primarily on the strengthening of chemical bonding and mechanical interlocking between the fiber and the matrix. The composite rupture planes indicated that the fracture failure shifted from the interface to the matrix or the fiber.

Keywords: PBO fiber; Oxygen plasma; Surface activation; Interfacial adhesion

Enhanced fatigue performance of porous coated Ti6Al4V biomedical alloy by I. Apachitei; A. Leoni; A.C. Riemslag; L.E. Fratila-Apachitei; J. Duszczyk (pp. 6941-6944).

► Synthesis of a microporous TiO₂ surface with Ca and P incorporation. ► Effect of porous coating on the in vitro fatigue strength of Ti6Al4V biomedical alloy. ► Shot peening prior to the porous coating enhanced the fatigue strength of Ti6Al4V alloy.Biofunctional coatings are necessary to improve integration of titanium implants in the host tissue but they may be detrimental for the implant fatigue properties. This study presents an attempt towards enhancement of the in vitro fatigue strength of plasma electrolytic oxidation coated Ti6Al4V alloy by applying shot peening process prior to coating. The electrolytic oxidation was performed in calcium acetate and calcium glycerophosphate electrolytes that allowed formation of porous oxide coatings with high surface free energy and apatite like ability. A deformed surface layer coupled with induced residual compressive stresses seem to affect oxide growth rate and fatigue behavior of the titanium alloy.

Keywords: Coating; Plasma electrolytic oxidation; Fatigue; Titanium; Biomaterials

Synthesis and structure of nitrogenated tetrahedral amorphous carbon films prepared by nitrogen ion bombardment by Han Liang; Chen Xian; Yang Li; Wang Yanwu; Wang Xiaoyan; Zhao Yuqing (pp. 6945-6951).

► In this paper, ion bombardment technology was used to fabricate ta-C:N film. ► The ta-C films with more than 80% sp³ fraction were deposited by filtered cathode vacuum arc (FCVA) technique, and then the energetic N ion was used to bombard ta-C film to fabricate ta-C:N film. ► The effect of N ion bombarding energy on the structure and surface morphology of ta-C:N film also was studied.The tetrahedral amorphous carbon (ta-C) films with more than 80% sp³ fraction firstly were deposited by filtered cathode vacuum arc (FCVA) technique. Then the energetic nitrogen (N) ion was used to bombard the ta-C films to fabricate nitrogenated tetrahedral amorphous carbon (ta-C:N) films. The composition and structure of the films were analyzed by visible Raman spectrum and X-ray photoelectron spectroscopy (XPS). The result shows that the bombardment of energetic nitrogen ions can induce the formation of CN bonds, the conversion of C–C bonds to CC bonds, and the increase of size of sp² cluster. The CN bonds are made of CN bonds and C–N bonds. The content of CN bonds increases with the increment of N ion bombardment energy, but the content of C–N bonds is inversely proportional to the increment of nitrogen ion energy. In addition, C≡N bonds are not existed in the films. By the investigation of AFM (atom force microscopy), the RMS (root mean square) of surface roughness of the ta-C film is about 0.21nm. When the bombarding energy of N ion is 1000eV, the RMS of surface roughness of the ta-C:N film decreases from 0.21 to 0.18nm. But along with the increment of the N ion energy ranging from 1400 to 2200eV again, the RMS of surface roughness of the ta-C:N film increases from 0.19 to 0.33nm.

Keywords: Nitrogenated tetrahedral amorphous carbon; N ion bombardment; Visible Raman spectrum; X-ray photoelectron spectroscopy

Microcalorimetric and thermodynamic studies of CO₂ and methanol adsorption on magnesium oxide by C. Pighini; T. Belin; J. Mijoin; P. Magnoux; G. Costentin; H. Lauron-Pernot (pp. 6952-6962).

Display Omitted► In the case of CO₂ adsorption on MgO, the adsorption isotherms and heat of adsorption curves are correctly described by Toth model. ► FTIR studies show that bicarbonates/bidendates ratio remains constant whatever the CO₂ amount on MgO samples. ► Cation doping of MgO samples: no increase of the basic character is observed; the amount of middle strength sites is improved; the trends of entropy change is not modified. ► The methanol adsorption on MgO is more sensitive to the cation doping than the CO₂ one.Both Lewis and Brönsted basic properties of magnesium oxide (MgO) are, respectively, studied by adsorption of CO₂ and methanol CH₃OH. Various chemical synthesis of pure magnesium oxide (commercial, sol–gel and precipitation methods) are used. The influence of small amounts of alkaline (Na⁺ and Li⁺) and alkaline-earth (Ca²⁺) cations is also reported. The amount and the strength of Lewis and Brönsted basic sites are determined by heat flow microcalorimetry. As observed with doped MgO samples, the amount of basic sites is increased but the strength of these sites remains the same. The observed strength of Brönsted sites is generally lower than the Lewis ones. These measurements reveal trends based on the synthesis process that can have an important impact on these basic properties.

Keywords: Magnesium oxide; Basic properties; CO; ₂; adsorption; Microcalorimetry; Infrared spectroscopy

Preparation of silver nanoparticle containing silica micro beads and investigation of their antibacterial activity by Dang Viet Quang; Pradip B. Sarawade; Askwar Hilonga; Jong-Kil Kim; Young Gyu Chai; Sang Hoon Kim; Jae-Yong Ryu; Hee Taik Kim (pp. 6963-6970).

► Silver nanoparticle coated silica micro beads (Ag-NPBs) were successfully prepared. ► Silver nanoparticles were mostly found at the outer layer of silica micro beads. ► Escherichia coli was completely inhibited after 5min contact with Ag-NPBs.Silver nanoparticle containing silica micro beads (Ag-NPBs) were successfully prepared by using sodium silicate, a cheap precursor, involving chemical reductive method. First, silica gel was synthesized and crushed into micro beads which have sizes ranging from 0.5 to 1mm. Silica micro beads were then modified with 3-aminopropyltriethoxysilane to graft amino functional groups onto their surface. Silver ions were loaded onto the surface of the modified silica and reduced to silver crystal by adding NaBH₄. The presence of silver nanoparticles as well as structure of materials was characterized with FT-IR, XRD, BET, FE-SEM, TEM, UV–vis spectrophotometer, and optical microscope. Silver nanoparticles with an average size about 5nm were found in the pore and on the surface of amino functionalized silica beads. Ag-NPBs samples were tested for their antibacterial activity against Escherichia coli ( E. coli). The antibacterial activity was examined by both zone inhibition and test tube test method. Biological results indicated that the synthesized materials have an excellent antibacterial performance against E. coli which was completely inhibited after 5min contact with Ag-NPBs.

Keywords: Silica micro beads; Silver nanoparticles; Sodium silicate; Antibacterial activity

Comparative study of simplex doped nc-WC/a-C and duplex doped nc-WC/a-C(Al) nanocomposite coatings by Shengguo Zhou; Liping Wang; S.C. Wang; Qunji Xue (pp. 6971-6979).

. Nanocomposite structure of as-fabricated coatings: (a) nc-WC/a-C coating and (b) nc-WC/a-C(Al) coating.Display Omitted► The as-fabricated coatings present typical nanocrystallite/amorphous structure. ► nc-WC/a-C(Al) has superior combining mechanical properties. ► nc-WC/a-C(Al) easily forms continuously compacted graphitized tribofilm under dry friction. ► The low-frictional behaviors of boundary-lubricated nanocomposites was governed by formation of WS₂-containing tribofilm.The existing challenges due to severely operating conditions of mechanical components require developing solid lubrication coatings with high hardness, good toughness as well as low friction coefficient. In this paper, the simplex W-doped nc-WC/a-C and duplex doped nc-WC/a-C(Al) nanocomposite coatings were successfully fabricated using magnetron sputtering process. The microstructure, mechanical properties and tribological behaviors of as-fabricated coatings were comparatively investigated. Results show that the WC1−_X nanocrystallites were formed and uniformly dispersed in the amorphous carbon matrix, while co-doping Al in the nanocomposite coating could drastically diminish the magnitude of internal stress and improve the adhesive strength as well as maintain the moderately high hardness. The significant improvement in the tribological performances of duplex doped nc-WC/a-C(Al) coating was mainly attributed to superior mechanical properties and the formation of continuously compacted graphitized tribofilm under dry friction as well as WS₂-containing tribofilm under oil lubrication. The good balance between hardness and toughness, low internal stress, superior low-friction and anti-wear properties of duplex doped nc-WC/a-C(Al) nanocomposite coating make it a good candidate as solid lubricating coating in engineering applications.

Keywords: Nanocomposite; nc-WC/a-C(Al); Low-friction; Anti-wear properties

Effect of sizing on carbon fiber surface properties and fibers/epoxy interfacial adhesion by Zhishuang Dai; Fenghui Shi; Baoyan Zhang; Min Li; Zuoguang Zhang (pp. 6980-6985).

► The sizing agent has an important influence on carbon fiber surface and its composites. ► This research has concluded that desized carbon fiber composites have higher interfacial shear strength. ► The sizing agent results in the presence of weak layer in fiber/resin interface region. ►γSD/γS of carbon fibers correlates well to the IFSS.This paper aims to study effect of sizing on surface properties of carbon fiber and the fiber/epoxy interfacial adhesion by comparing sized and desized T300B and T700SC carbon fibers. By means of X-ray photoelectron spectroscopy (XPS), activated carbon atoms can be detected, which are defined as the carbon atoms conjunction with oxygen and nitrogen. Surface chemistry analysis shows that the desized carbon fibers present less concentration of activated carbon, especially those connect with the hydroxyl and epoxy groups. Inverse gas chromatography (IGC) analysis reveals that the desized carbon fibers have larger dispersive surface energyγSD and smaller polar componentγSSP than the commercial sized ones. Moreover, micro-droplet test shows that the interfacial shear strength (IFSS) of the desized carbon fiber/epoxy is higher than those of the T300B and T700SC. Variations of the IFSS for both the sized and desized carbon fibers correspond toγSD/γS tendency of the fiber surface, however the work of adhesion does not reveal close correlation with IFSS trend for different fiber/epoxy systems.

Keywords: Composites; Carbon fibers; Sizing; Surface energy; Interfacial shear strength

Density functional theory study of the chemisorption of CO on Ir/MgO(100) by Y.C. Chen; L.J. Song; Z.L. Sun (pp. 6986-6990).

► Top and bridge adsorption sites for iridium atom deposited on MgO(100) surface have been considered. ► Perpendicular and parallel adsorbate arrangements have been considered to study the chemisorption of CO on Ir/MgO(100). ► Electronic structure analysis shows that the 5 d states of Ir atoms on the MgO(100) surface are very active. ► The most stable CO chemisorption geometry is C-down oriented in the three possible geometry structure.Density functional theory calculations have been used to study the adsorption of CO on the Ir/MgO(100). Substrate and adsorbate geometry relaxation, adsorption, energy and density of states are computed. Top and bridge adsorption sites for iridium atom deposition have been considered. The result indicated that the energetically most favorable sites are the top sites of the O atoms. CO adsorption on the Ir atom is then studied. Different adsorbate arrangements, perpendicular and parallel to the surface have been considered. Among them, the most stable CO chemisorption geometry, is that corresponding to the adsorbate perpendicular to the surface iridium atom and C-down oriented. Density of states and the CO stretching frequency analysis further found that the obvious charge transfer from adsorbate to the substrate.

Keywords: PACS; 82.37.Np; 68.47.−b; 82.65.+rHeterogeneous catalysis; Adsorption; Iridium; Density functional theory; Carbon monoxide

Facile and mild preparation of fluorescent ZnO nanosheets and their bioimaging applications by Hui Jiang; Huangping Wang; Xuemei Wang (pp. 6991-6995).

► ZnO nanosheets have been synthesized under mild conditions. ► Triethanolamine plays the dual roles in the synthesis. ► ZnO nanosheets display visible yellow-orange emission. ► ZnO nanosheets may be applied in the cellular imaging.A viscous tertiary amine and triol, triethanolamine, is engaged in this work as a structure-shaping agent to prepare the high-quality ZnO nanosheets under mild conditions, i.e., at nearly neutral pH and low temperature. The X-Ray diffraction and transmission electron microscopic results validated that the obtained ZnO nanosheets show the perfect hexagonal nanostructures, with an average edge length of 46.6±8.5nm. The triethanolamine molecule is deemed to act as the hydroxide anion generator as well as the surface modification agent, as evidenced by the FT-IR spectrum. The mechanism for the formation of ZnO nanosheets has been discussed. The simple strategy allows the efficient syntheses of fluorescent ZnO with the strong emission around 560nm, which was attributed to the defect emission of the ZnO nanostructures. The predominant fluorescent properties have been successfully used in the field of cellular imaging, suggesting their promising biomedical applications.

Keywords: Nanomaterials; Semiconductors; Zinc oxide; Fluorescence; Bioimaging

Modification of the surface properties of a polyimide film during irradiation with polychromic light by Liliana Rosu; Ion Sava; Dan Rosu (pp. 6996-7002).

► Polyimide films surface exhibits structural changes during polychromic light irradiation, being affected the benzophenone structure and the imide bond. ► Significant changes in color and gloss of polyimide films surface were observed during irradiation. ► A mechanism for the photochemical degradation of polyimide film was proposed considering structural changes recorded during irradiation.The behaviour of a polyimide film with the aromatic structure during the exposure to UV light with λ>290nm was studied. Significant changes in color surface and gloss surface were identified during irradiation. Sample became lighten and less glossy after exposure to the light.These modifications were correlated with the structural changes in FTIR spectra. Based on changes in FTIR spectra recorded during irradiation, a mechanism for the photochemical degradation of polyimide film was proposed.

Keywords: Polyimide; UV irradiation; Photodegradation; Mechanism; Color change; Gloss variation

Design of an outstanding super-hydrophobic surface by electro-spinning by Manas K. Sarkar; Kausik Bal; Fuen He; Jintu Fan (pp. 7003-7009).

► Superhydrophobic surface is engineered with PVDF and fluorinated Si-molecules. ► Surface structure is optimized based on analysis of surface morphology. ► Aspect ratio of particles and hierarchical structure are used to optimize the surface. ► Extreme aquaphobic surface is developed by variable electrospraying in two layers.A duel-layer super-hydrophobic surface, comprising polyvinylidene fluoride (PVDF) and fluorinated silane molecules (FSM), was engineered using electro-spinning a coating onto the glass. Scanning electron microscopy was used to confirm that, by reducing the percentage of PVDF in the spraying solution, the aspect ratio of the nano-beads could be changed and a sharp bead profile obtained. Energy dispersive spectroscopy was employed to ensure the maximum amount of FSM was present on the surface, which assists in achieving a high Water Contact Angle. Using a two-step process, involving PVDF and FSM, nano-beads, with high aspect ratio, were formed on a rough surface which produced a super-hydrophobic surface with a Water Contact Angle of 170.2° and a very low Water Roll-off Angle (<1°). Such a coating facilitates the speedy run-off of water drops from a surface and has many potential applications in buildings and other areas.

Keywords: Superhydrophobic; Electro-spinning; Water Contact Angle; Aspect ratio; Nano-beads; Nano-fibers

One-step approach for hydroxyapatite-incorporated TiO₂ coating on titanium via a combined technique of micro-arc oxidation and electrophoretic deposition by Yu Bai; Il Song Park; Sook Jeong Lee; Tae Sung Bae; Warwick Duncan; Michael Swain; Min Ho Lee (pp. 7010-7018).

► Electrophoretic deposition and micro-arc oxidation are combined. ► The variation of applied voltage affects the surface characteristics of titanium implant. ► An applied voltage of 350V is the optimal choice.A porous hydroxyapatite (HA) – incorporated TiO₂ coating layer was deposited on the titanium substrate using a combination of micro-arc oxidation and electrophoretic deposition. The size of the synthesized HA nano-particles was approximately 10–20nm in width and 30–40nm in length. The microstructure, as well as elemental and phase composition of the coating layers were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). XRD showed that the coating layers were composed mainly of HA and anatase phases. The composition and surface morphologies were strongly dependent on the applied voltages. The amount of HA deposited into the coating increased with increasing applied voltage. The corrosion behavior of the coating layers in the simulated body fluids (SBF) was evaluated using a potentiodynamic polarization test. The corrosion resistance of the coated sample was higher than that of the untreated titanium sample. Moreover, the corrosion resistance of the coated samples also showed a positive correlation with the applied voltage. In addition, the in vitro cellular responses to the coated samples were assessed to investigate the proliferation, differentiation and morphology of the osteoblast cell line.

Keywords: Micro-arc oxidation; Electrophoretic deposition; Applied voltage; Hydroxyapatite; Bioactivity

Preparation of high transmittance ZnO:Al film by pulsed filtered cathodic arc technology and rapid thermal annealing by F. Gao; K.M. Yu; R.J. Mendelsberg; A. Anders; W. Walukiewicz (pp. 7019-7022).

► ZnO:Al films with high visible and infrared transmittance properties were prepared on glass substrates by the pulsed filtered cathodic arc technique and rapid thermal annealing. ► As the annealing temperature increases from 500°C to 650°C, the visible transmittance remains nearly constant (∼85%) while the infrared (780–2500nm) transmittance considerably improves from 22% for the as-deposited film to 58% at 600°C and 71% at 650°C at 2500nm for the annealed films. ► The high-temperature annealing improved the crystallinity and transmittance of the films.Approximately 200nm thick ZnO:Al films with high visible and infrared transmittance properties were prepared on glass substrates by the pulsed filtered cathodic arc technique and rapid thermal annealing. The as-deposited and annealed films have a poly-crystalline hexagonal wurtzite type structure. As the annealing temperature increases from 500°C to 650°C, the visible transmittance remains nearly constant (∼85%) while the infrared (780–2500nm) transmittance considerably improves from 22% for the as-deposited film to 58% at 600°C and 71% at 650°C at 2500nm for the annealed films. However, the electrical properties of the films worsen after high-temperature annealing, and resistivity increases from 2.5×10⁻⁴Ωcm for the as-deposited film to 3.6×10⁻³Ωcm and 1.2×10⁻²Ωcm for the films annealed at 600 and 650°C, respectively. The high-temperature annealing improved the crystallinity and transmittance of the films. Nevertheless, these improvements may lead to the segregation and oxidation of aluminum atoms, as well as the reduction of oxygen vacancies, thereby degrading the electrical properties of the films.

Keywords: PACS; 81.15.Jj; 52.77.Dq; 81.40.Ef; 81.40.Tv; 73.61.LeZnO:Al films; Cathodic arc deposition; Rapid thermal annealing; Transmittance; Resistivity

Corrigendum to “Composited BCN/carbon fibers prepared by hot-filament chemical vapor deposition” [Appl. Surf. Sci. 257 (2011) 4963–4967] by Jiannan Lü; Hongdong Li; Pinwen Zhu; Xianyi Lü; Yingai Li (pp. 7023-7023).

Erratum to “Oxidation of TiNi surface with hyperthermal oxygen molecular beams” [Appl. Surf. Sci. 257 (2011) 4257] by Michio Okada; Makoto Souwa; Toshio Kasai; Yuden Teraoka (pp. 7024-7024).

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Applied Surface Science (v.257, #15)