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Applied Surface Science (v.257, #16)

Structural and electrical properties of evaporated Fe thin films by M. Mebarki; A. Layadi; A. Guittoum; A. Benabbas; B. Ghebouli; M. Saad; N. Menni (pp. 7025-7029).

► Evaporated Fe thin films in the 76–431nm thickness range. ► The surface morphology, the structural and electrical properties are investigated. ► The effect of substrate (glass, Si), deposition rate and thickness are studied. ► Texture, grain size, strain and electrical resistivity depend on the substrate. ► Higher deposition rate induces droplets on the surface with greater density in Fe/Si.Series of Fe thin films have been prepared by thermal evaporation onto glass and Si(100) substrates. The Rutherford backscattering (RBS), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and the four point probe techniques have been used to investigate the structural and electrical properties of these Fe thin films as a function of the substrate, the Fe thickness t in the 76–431nm range and the deposition rate. The Fe/Si samples have a 〈110〉 for all thicknesses, whereas the Fe/glass grows with a strong 〈100〉 texture; as t increases (>100nm), the preferred orientation changes to 〈110〉. The compressive stress in Fe/Si remains constant over the whole thickness range and is greater than the one in Fe/glass which is relieved when t>100nm. The grain size D values are between 9.2 and 30nm. The Fe/glass films are more electrically resistive than the Fe/Si(100) ones. Diffusion at the grain boundary seems to be the predominant factor in the electrical resistivity ρ values with the reflection coefficient R greater in Fe/glass than in Fe/Si. For the same thickness (100nm), the decrease of the deposition rate from 4.3 to 0.3Å/s did not affect the texture and the reflection coefficient R but led to an increase in D and a decrease in the strain and in ρ for both Fe/glass and Fe/Si systems. On the other hand, keeping the same deposition rate (0.3Å/s) and increasing the thickness t from 76 to 100nm induced different changes in the two systems.

Keywords: Thin films; Fe; Structure; XRD; RBS; SEM; Electrical resistivity

Optical and electrochemical properties of ordered macroporous gold array on the ITO surface by Huidan Lu; Yongping Liu; Guo-Cheng Han (pp. 7030-7035).

► In this work, we presented a new type of OTEs material-macroporous gold array. ► The SEM pictures exhibits that the close-packed macropore constituted the gold array of large area, and the absorbance spectrum indicates that macroporous gold array has excellent light transmission, so it was used to optically transparent electrode. ► The OTE was successfully served as work electrode of thin-layer cell in order to evaluate electrochemical and light properties of macroporous gold array. ► In summary, the MGA with excellent performance offers a new choice for electrode material of light transmission, and a new application field of macroporous material is opened up.The electrochemical and optical properties of transparent, two-dimensional macroporous gold film were investigated. Colloidal crystal templates were assembled onto indium-doped tin oxide (ITO) glass surface through vertical depositing method. Following gold electrodeposition, they were removed by dissolution with tetrahydrofuran (THF). The highly ordered macroporous gold array was achieved. It was characterized by scanning electron microscope (SEM) and ultraviolet visible (UV–vis) spectrophotometry. The optical transparency of the gold film was near 25% and fairly constant between 300 and 900nm. The macroporous gold film electrode was mounted into a thin-layer transmission cell. The electrochemical response was evaluated by thin-layer cyclic voltammograms (CV) of the Fe (CN)₆³⁻/Fe (CN)₆⁴⁻ couple. Thin-layer cell exhibits good shape of waves and nearly symmetric cathodic and anodic waves. E⁰′ value and n of TMPD⁺/TMPD (TMPD is acronyms for N,N,N′,N′-tetramethyl-p-phenylenediamine, and TMPD⁺ is its mono-cation radical) couple were determined. Furthermore, results demonstrated electrolytic equilibrium was faster reached in macroporous gold film than ITO electrode.

Keywords: Macroporous gold array; ITO surface; Optical transparent electrodes; Thin-layer spectroelectrochemistry

Annealing ambient on the evolution of He-induced voids in silicon by B.S. Li; C.H. Zhang; Y.R. Zhong; D.N. Wang; L.H. Zhou; Y.T. Yang; L.Q. Zhang; H.H. Zhang; Y. Zhang; L.H. Han (pp. 7036-7040).

► Open-volume defects could be influenced by annealing ambient in He-implanted silicon. ► Void concentration decreases with the increase in the thickness of epitaxy.The effects of annealing ambient on the He-induced voids in silicon were investigated using the combination of the Doppler broadening spectroscopy using a variable-energy positron beam and cross-section transmission electron microscopy (XTEM). A 〈100〉-oriented silicon wafer was implanted with He ions at an energy of 15keV to a dose of 2×10¹⁶cm⁻² at room temperature. Post-implantation, the samples were annealed at a temperature of 1000°C in the ambient of vacuum, argon, nitrogen, air and oxygen. Positron annihilation spectroscopy (PAS) spectra varied with the annealing ambient. XTEM micrographs demonstrated that the density of He-induced voids could be influenced by the annealing ambient.

Keywords: Silicon; Positron annihilation; Void; Annealing ambient; TEM

CdS/PbS co-sensitized ZnO nanorods and its photovoltaic properties by Chengcheng Liu; Zhifeng Liu; Yabin Li; Jing Ya; Lei E; Li An (pp. 7041-7046).

► CdS and PbS nanoparticles co-sensitized ZnO nanorods as photoanode of DSSCs. ► CdS and PbS sensitized ZnO by SILAR. ► High cell efficiency of ZnO/CdS/PbS mainly due to the stepwise band edge structure.Nanoparticles co-sensitized nanorods were designed and prepared by assembled CdS and PbS nanoparticles over ZnO nanorods using successive ionic layer adsorption and reaction (SILAR) method. The results showed that the uniform CdS and PdS nanoparticles could be deposited on the lateral and top of the ZnO nanorods when the precursor concentration was 0.05M and 0.02M, respectively. Solar cells based on CdS and PbS nanoparticles sensitized ZnO nanorods arrays were assembled successfully. A cell efficiency of 0.38% was obtained in ZnO/CdS/PbS in comparison with ZnO/PbS/CdS mainly due to the stepwise band edge structure constructed in this system except the coverage density of nanoparticles.

Keywords: CdS; PbS; Co-sensitization; ZnO nanorods; Solar cell

Roles of oleic acid during micropore dispersing preparation of nano-calcium carbonate particles by Jiuxin Jiang; Jie Liu; Chang Liu; Gaowen Zhang; Xinghou Gong; Jianing Liu (pp. 7047-7053).

► Nano-CaCO₃ particles have been successfully prepared by micropore dispersion method. ► Oleic acid is introduced as surfactant during micropore dispersion preparation. ► The addition of oleic acid can reduce the size of nano-CaCO₃ particles. ► Two opposite roles of oleic acid in the preparation of CaCO₃ are concluded.In the present work, nano-calcium carbonate powder was prepared by micropore dispersion method with assistance of oleic acid as surfactant. CO₂ gas was dispersed into the Ca(OH)₂/H₂O slurry via a glass micropore-plate with the diameter of micropore about 20μm. To investigate the effect of oleic acid on the size of CaCO₃ particles, different amount of oleic acid was added in Ca(OH)₂/H₂O slurry at 5°C and 25°C, respectively. XRD patterns show that cubic calcite is the only crystalline phase in all cases. ZPA data and TEM photo indicate that the average particle size synthesized at 5°C without oleic acid is of about 40nm, slightly smaller than that of prepared at 25°C, and that the dispersity of sample prepared at 5°C is better than that of 25°C. When oleic acid is added in both temperatures, the average particle size decreases a little. FT-IR spectra demonstrate that oleic acid interacts with Ca²⁺ and carbon–carbon double bond existed on the surface of particle. Consequently, two opposite roles of oleic acid during the process of preparation of nano-CaCO₃ were proposed, namely preventing nanoparticles from growing during reaction and making nanoparticles reunite to a certain extent after reaction.

Keywords: Nano-CaCO; ₃; Micropore dispersion; Oleic acid; Carbonation; Surfactant

Fabrication of superhydrophobic binary nanoparticles/PMMA composite coating with reversible switching of adhesion and anticorrosive property by XiangHui Xu; ZhaoZhu Zhang; Fang Guo; Jin Yang; XiaoTao Zhu (pp. 7054-7060).

Display Omitted► Superhydrophobic Ag-TiO₂-Thiol/PMMA coatings with the capability of UV absorption have been fabricated by spray method. ► The coatings show notable stability in different medium conditions (in acidic (pH=1) and basic (pH=14) solution, in artificial seawater (ASTMD1141-98 one week). ► The superhydrophobic coatings are anticorrosive and provide an easy way to protect metal materials effectively.Ag–TiO₂–Thiol/Poly(methyl methacrylate) (PMMA) coating has been prepared via adsorbed-layer nanoreactor technique and self-assembling method. The composite coating shows a superhydrophobic property with reversible switching of adhesion. In the UV–vis spectra, absorption appeared in ultraviolet region of 229–293nm (UVC region) and 320–370nm (UVA region). Additionally, the stability of the superhydrophobic surface was tested under the following conditions: (1) in basic solution (pH=14); (2) in acid solution (pH=1); (3) in artificial seawater. The coating shows stability since the contact angle of the sample still remained higher than 150° in the above conditions. The corrosion resistance of the superhydrophobic surfaces was investigated by electrochemical measurements and the results revealed that the superhydrophobic coatings are anticorrosive well.

Keywords: Binary nanoparticles; Superhydrophobic; UV absorption; Anticorrosion

Rapid thermal annealing of ITO films by Shumei Song; Tianlin Yang; Jingjing Liu; Yanqing Xin; Yanhui Li; Shenghao Han (pp. 7061-7064).

► ITO films were deposited at room temperature. ► ITO films were treated by rapid thermal annealing (RTA) in vacuum. ► ITO films after annealed by RTA shows the lowest resistivity of 1.6×10⁻⁴Ωcm. ► High transmittance (above 90%) is exhibited by the ITO films.Tin-doped indium oxide (ITO) films with 200nm thickness were deposited on glass substrates by DC magnetron sputtering at room temperature. And they were annealed by rapid thermal annealing (RTA) method in vacuum ambient at different temperature for 60s. The effect of annealing temperature on the structural, electrical and optical properties of ITO films was investigated. As the RTA temperature increases, the resistivity of ITO films decreases dramatically, and the transmittance in the visible region increases obviously. The ITO film annealed at 600°C by RTA in vacuum shows a resistivity of 1.6×10⁻⁴Ωcm and a transmittance of 92%.

Keywords: PACS; 73.21.Ac, 73.40.VzITO film; Rapid thermal annealing; Resistivity; Transmittance

The sterilization of Escherichia coli by dielectric-barrier discharge plasma at atmospheric pressure by Hu Miao; Guo Yun (pp. 7065-7070).

► The E. coli on the surface of PTFE, PVC, and PET is sterilized by DBD air plasma. ► Extending time, decreasing gap spacing and cell density enhance inactivation effect. ► The efficiency is 99.999% by 5min, 3-cm gap spacing and on PET films. ► Protein leakage and cell morphology alteration revealed the etching on cell membrane.The sterilization of E. coli (ATCC8099) using an atmospheric pressure, air DBD plasma driven by 100Hz high-voltage power supply was investigated in this paper. The results showed that germicidal efficiency was closely related to the plasma treatment time, the gap spacing, the initial cell density and the surface characters of substrate materials. The germicidal efficiency was 99.999% under the conditions of 5-min plasma treatment, 3-cm gap spacing and on PET films. After plasma exposure for 5min, the temperature was observed below 43°C which could not lead to inactivate E. coli. The observation of protein leakage and cell morphology alteration by transmission electron microscopy (TEM) techniques revealed that the etching action on cell membrane by electrons, ions and radicals was primary reason of DBD air plasma sterilization.

Keywords: Plasma; DBD; Escherichia coli; Sterilization

The effect of surface morphology on the response of Fe₂O₃-loaded vanadium oxide nanotubes gas sensor by Wei Jin; Wen Chen; Yue Li; Chunxia Zhao; Ying Dai (pp. 7071-7075).

► Attempts were first made to control the particle size and deposition of Fe₂O₃ by a novel citric acid-assisted hydrothermal method, where citric acid used as surfactant and chelate agent. ► The influence of the size and loading amount of Fe₂O₃ particles on the sensor response was been suspected. ► The effect of Fe₂O₃ loading amount on sensor response can indeed be explained as active sites. While, the effects of Fe₂O₃ particle size on the sensor resistance were interpreted in terms of the Debye length.The effect of surface morphology on the response of an ethanol sensor based on vanadium nanotubes surface loaded with Fe₂O₃ nanoparticles (Fe₂O₃/VONTs) was investigated in this work. The particle size of Fe₂O₃ loaded on VONTs was varied by using novel citric acid-assisted hydrothermal method. In the synthesis progress, citric acid was used as a surfactant and chelate agent, which ensured the growth of a uniform Fe₂O₃ loading on the nanotubes surface. The ethanol sensing properties was then measured for these Fe₂O₃/VONTs at 230–300°C. The results showed that the sensor response increased with the particles size and the loading amount of Fe₂O₃. It appears that the load of Fe₂O₃ on the VONTs surface increases the concentration of oxygen vacancies and decreases the concentration of free electrons. The effects of morphology on the sensor resistance were interpreted in terms of the Debye length and the difference in the number of active sites.

Keywords: Vanadium oxide nanotubes; Fe; ₂; O; ₃; nanoparticles; Loading; Surface morphology; Gas sensor

The effect of the deposition parameters on size, distribution and antimicrobial properties of photoinduced silver nanoparticles on titania coatings by Ireneusz Piwoński; Kinga Kądzioła; Aneta Kisielewska; Katarzyna Soliwoda; Marian Wolszczak; Katarzyna Lisowska; Natalia Wrońska; Aleksandra Felczak (pp. 7076-7082).

► Precise control of the growth of silver nanoparticles on titania coatings, including their size and distribution, by changing such parameters like silver ions concentration, the time of illumination and the illumination UV source. ► Correlation of the morphology of resulted nanocomposite coatings with their antimicrobial activity. ► Comparison of the illumination sources (UV xenon lamp and excimer laser) in effectiveness of Ag nanoparticles deposition.Controlled photodeposition of silver nanoparticles (AgNP) on titania coatings using two different sources of UV light is described. Titania (anatase) thin films were prepared by the sol–gel dip-coating method on silicon wafers. AgNPs were grown on the titania surface as a result of UV illumination of titania films immersed in aqueous solutions of silver nitrate. UV xenon lamp or excimer laser, both operating at the wavelength 351±5nm, was used as illumination sources. The AFM topography of AgNP/TiO₂ nanocomposites revealed that silver nanoparticles could be synthesized by both sources of illumination, however the photocatalysis carried out by UV light from xenon lamp illumination leads to larger AgNP than those synthesized using the laser beam. It was found that the increasing concentration of silver ions in the initial solution increases the number of Ag nanoparticles on the titania surface, while longer time of irradiation results the growth of larger size nanoparticles. Antibacterial tests performed on TiO₂ covered by Ag nanoparticles revealed that increasing density of nanoparticles enhances the inhibition of bacterial growth. It was also found that antibacterial activity drops by only 10–15% after 6 cycles compared to the initial use.

Keywords: Silver nanoparticles; Titanium dioxide; Photodeposition; UV illumination; AFM; Antimicrobial

Preparation, characterization and visible-light photocatalytic activity of AgI/AgCl/TiO₂ by Jing Cao; Benyan Xu; Bangde Luo; Haili Lin; Shifu Chen (pp. 7083-7089).

A novel AgI/AgCl/TiO₂ composite photocatalyst was synthesized by ion exchange method. The photoactivity of the AgI/AgCl/TiO₂ is much higher than that of AgCl/TiO₂ and AgI/TiO₂ under visible-light irradiation ( λ>400nm) in the process of methyl orange (MO) degradation. The activity enhancement of AgI/AgCl/TiO₂ can be ascribed to the effective electron–hole separation at AgI/AgCl and AgCl/TiO₂ heterojunction interfaces, which facilitate the transfer of the photoinduced carriers. The superoxide radical anions (O₂⁻) and hydrogen peroxide (H₂O₂) are the reactive species and play the dominant role for the MO degradation in the AgI/AgCl/TiO₂ photocatalysis process.Display Omitted► AgI/AgCl/TiO₂ was prepared successfully by a simple ion exchange method. ► AgI/AgCl/TiO₂ displays much higher photocatalytic activity than AgCl/TiO₂ and AgI/TiO₂. ►O₂⁻ radicals and H₂O₂ were proven to be the main active species.In this paper, a novel composite photocatalyst AgI/AgCl/TiO₂ was prepared by ion exchange method and characterized by XRD, SEM and UV–Vis spectrometry. The as-prepared AgI/AgCl/TiO₂ composites show much higher photocatalytic activity than AgCl/TiO₂ and AgI/TiO₂ under visible-light irradiation ( λ>400nm) in the process of methyl orange (MO) degradation. When the molar percentage of AgI to initial AgCl is 20% (sample SE-20%), the maximal degradation efficiency of MO has reached 85.8% after irradiation for 120min. The enhancement of photocatalytic activity of the composite photocatalyst AgI/AgCl/TiO₂ will be attributed to its good absorption in the visible-light region, especially low recombination rate of the electron–hole pairs based on the photoluminescence (PL) spectra investigation of AgI/AgCl/TiO₂ and the matching band structures of AgI, AgCl and TiO₂. The detection of reactive species by radical scavengers displays thatO₂⁻ and H₂O₂ are the main reactive species for the degradation of MO under visible-light irradiation. Moreover, PL analysis by using terephthalic acid (TA) as a probe molecule further reveals thatOH can be negligible for the degradation of MO.

Keywords: AgI/AgCl/TiO; ₂; Visible-light photocatalysis; Methyl orange; Photocatalytic mechanism

Characterization of immobilization methods of antiviral antibodies in serum for electrochemical biosensors by Tran Quang Huy; Nguyen Thi Hong Hanh; Pham Van Chung; Dang Duc Anh; Phan Thi Nga; Mai Anh Tuan (pp. 7090-7095).

► A comparative study of different immobilizations of serum antibodies on the silanized surface was performed for optimizing electrochemical detection. ► Protein A revealed as a good bio-molecule for improvement and orientation of serum antibodies on the silanized surface. ► The most effective method of serum antibodies immobilization was tested on the protein A/ glutaraldehyde/ silanized interdigitated surface. ► The potential development of serum antibodies based biosensors could be realized for rapid and direct detection of viral antigens.In this paper, we describes different methods to immobilize Japanese encephalitis virus (JEV) antibodies in human serum onto the interdigitated surface of a microelectrode sensor for optimizing electrochemical detection: (1) direct covalent binding to the silanized surface, (2) binding to the silanized surface via a cross-linker of glutaraldehyde (GA), (3) binding to glutaraldehyde/silanized surface via goat anti-human IgG polyclonal antibody and (4) binding to glutaraldehyde/silanized surface via protein A (PrA). Field emission scanning electron microscopy, Fourier transform infrared spectrometry, and fluorescence microscopy are used to verify the characteristics of antibodies on the interdigitated surface after the serum antibodies immobilization. The analyzed results indicate that the use of protein A is an effective choice for immobilization and orientation of antibodies in serum for electrochemical biosensors. This study provides an advantageous immobilization method of serum containing antiviral antibodies to develop electrochemical biosensors for preliminary screening of viruses in clinical samples from outbreaks.

Keywords: Serum antibodies immobilization; Biointerfaces; Protein A; Electrochemical biosensors; Preliminary pathogenic screening

A promising approach to conductive patterns with high efficiency for flexible electronics by Yan-Long Tai; Zhen-Guo Yang; Zhi-Dong Li (pp. 7096-7100).

► Stable conductive ink with no solid particles and conductive pen were prepared. ► PI-based conductive patterns for flexible electronics were obtained by direct-writing. ► The design of conductive ink and sintering processing were studied. ► Conductive mechanism of the conductive ink was analyzed. ► Mechanical/electrical fatigue properties of conductive patterns were investigated.A promising approach for conductive patterns with high efficiency for flexible electronics was developed by direct-writing, silver(I) solution (silver nitrate, acetate silver, etc.) with no solid particles as a conductive ink, conductive pen as a writing implement, and polyimide (PI) film as a substrate. The physical properties of the conductive ink were investigated by a dynamic contact angle system, ubbelohde viscometer and surface tension instrument. Conductive properties of silver ink film were investigated by 4-point probe, scanning electron microscope (SEM) and surface profilometer. It is demonstrated how the design of solvent composition in conductive ink affects surface morphology, and conductivity of silver ink films. It can be obtained that conductive patterns drawn on PI substrate not only have good mechanical/electrical fatigue properties, but also have low resistivity. Especially, when the sintering condition is 200°C for 60min, the resistivity can be down to 6.6μΩcm, 4.25 times the silver bulk resistivity.

Keywords: Flexible electronics; Conductive ink; Conductive pen

Effect of laser surface hardening on the microstructure, hardness and residual stresses of austempered ductile iron grades by C. Soriano; J. Leunda; J. Lambarri; V. García Navas; C. Sanz (pp. 7101-7106).

► Nd:YAG laser surface hardening of low-medium and upper austempered ductile irons. ► Few differences on the microstructure, case depth and residual stresses of the grades. ► Coarse martensite, retained austenite structures with the graphite nodules unaltered. ► Compressive residual stresses bound to microstructural and microhardness changes. ► Laser hardening improves wear resistance and mechanical properties of ADI grades.A study of the laser surface hardening process of two austempered ductile iron grades, with different austempering treatments has been carried out. Hardening was performed with an infrared continuous wave Nd:YAG laser in cylindrical specimens. The microstructure of the laser hardened samples was investigated using an optical microscope, microhardness profiles were measured and surface and radial residual stresses were studied by an X-ray diffractometer. Similar results were achieved for both materials. A coarse martensite with retained austenite structure was found in the treated area, resulting in a wear resistant effective layer of 0.6mm to 1mm with a microhardness between 650HV and 800HV. Compressive residual stresses have been found at the hardened area being in agreement with the microhardness and microstructural variations observed. The achieved results point out that the laser surface hardening is a suitable method for improving the mechanical properties of austempered ductile irons.

Keywords: Laser surface hardening; Austempered ductile iron; Residual stresses; Microstructure; Hardness

A facile synthesis of monodisperse CoFe₂O₄/SiO₂ nanoparticles by Hai Wang; Jun Huang; Liyun Ding; DaPeng Li; Yun Han (pp. 7107-7112).

► Monodisperse CoFe₂O₄/SiO₂ NPs with high amino groups’ density were obtained. ► Monodisperse CoFe₂O₄/SiO₂ nanoparticles have superparamagnetism, indicating that the CoFe₂O₄/SiO₂ can be used as carrier for the enzyme immobilization. ► Aminated-CoFe₂O₄/SiO₂ magnetic nanoparticles were prepared by a facile method.Aminated-CoFe₂O₄/SiO₂ magnetic nanoparticles (NPs) were prepared from primary silica particles using modified StÖber method. By optimizing the preparation conditions, monodisperse CoFe₂O₄/SiO₂ NPs with high amino groups’ density were obtained, which is necessary for enzyme immobilization. TEM confirm that the sample is a core/shell structure. These aminated-CoFe₂O₄/SiO₂ NPs have narrow size distributions with a mean size of about 60nm. Moreover, the aminated-CoFe₂O₄/SiO₂ NPs can be easily dispersed in aqueous medium. The experimental results also show that the NPs have superparamagnetism, indicating that the aminated-CoFe₂O₄/SiO₂ NPs can be used as an effective carrier for the enzyme immobilization.

Keywords: CoFe; ₂; O; ₄; /SiO; ₂; nanoparticles; Monodispersity; Carrier

Helium/oxygen atmospheric pressure plasma jet treatment for hydrophilicity improvement of grey cotton knitted fabric by Liqiang Tian; Huali Nie; Nicholas P. Chatterton; Christopher J. Branford-White; Yiping Qiu; Limin Zhu (pp. 7113-7118).

► The influence of He/O₂ atmospheric pressure plasma jet (APPJ) treatment on the hydrophilicity of grey cotton fabrics. ► We observed that the ability of helium/oxygen APPJ directly etching the waxy layer and modifying the surface properties of grey cotton fabric was deficient, dewaxing process prior to plasma treatment was the key step to achieve the hydrophilic surface. ► We analyzed the mutual epiphytic relationship between pectins and waxes in the cuticle layer by plasma-aided.The influence of atmospheric pressure plasma jet (APPJ) treatment on the hydrophilicity of grey cotton knitted fabric (GCKF) was investigated. For comparison, specimens which had undergone different treatments were tested by contact angle measurement, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), fourier-transform infrared attenuated total reflectance spectroscopy (FTIR-ATR) and X-ray diffraction (XRD). The results imply that helium/oxygen APPJ could improve the hydrophilicity of GCKF by modifying the surface properties. In addition, combining dewaxing processes with He/O₂ APPJ treatment was found to tremendously improve the hydrophilicity of GCKF. The mechanism of this was also confirmed by Ruthenium Red staining which showed most of pectic substances inside the cotton fiber existed beneath the waxy layer and on top of the cellulose microfibril.

Keywords: Grey cotton knitted fabric; Atmospheric pressure plasma jet; Dewaxing; Hydrophilicity; XPS

Low-temperature deposited ZnO thin films on the flexible substrate by cathodic vacuum arc technology by Ru-Yuan Yang; Min-Hang Weng; Cheng-Tang Pan; Chin-Min Hsiung; Chun-Chih Huang (pp. 7119-7122).

► Low-temperature deposited un-doped ZnO films are successful prepared on PET substrates by using CAPD system. ► The effect of film thickness on the microstructure, optical and electrical properties of low-temperature deposited un-doped ZnO films by CAPD were investigated and discussed. ► This report may give significant information about how to deposit high quality ZnO thin films with desired optical and/or electrical properties at a low temperature using CAPD on the applications to be a newer alternatives to ITO in the display industries.In this paper, un-doped zinc oxide (ZnO) films with various thicknesses (150, 250, 350, 450 and 550nm) were successfully prepared onto PET substrates using cathodic vacuum arc technique at low-temperature (<40°C). Their microstructure, optical and electrical properties were investigated and discussed. The films showed (002) peaks, an average transmittance over 80% in the visible region. Calculated values of the band gap are around 3.29–3.33eV when the film thickness increased, indicating a slight blue shift of optical transmission spectra. The lowest resistivity about 5.26×10⁻³Ωcm could be achieved for the un-doped ZnO film with thickness of 550nm.

Keywords: ZnO; Cathodic vacuum arc; PET; Thin film

Preparation, characterization and properties of amino-functionalized montmorillonite and composite layer-by-layer assembly with inorganic nanosheets by Guo-bo Huang; Chang-hua Ge; Bing-jing He (pp. 7123-7128).

► Amino-functionalized montmorillonite (APTMS-MMT) was prepared by the ultrasonic process. ► The ultrasonic process improved the stability of MMT suspension. ► The ultrasonic process of increased the dispersability of MMT in the PAA matrix. ► The ultrasonic process improved greatly the mechanical properties of the composites.An amino-functionalized montmorillonite (APTMS-MMT) was prepared by the grafting of 3-aminopropyltrimethoxysilane (APTMS) on the surface of MMT via the ultrasonic synthesis process and characterized by a variety of techniques: FT-IR, thermogravimetic analysis (TGA), particles size analysis and ζ-potential measurement. The results showed the size and size distribution of APTMS-MMT particles were decreased, and the ζ-potential of particles was increased obviously via the ultrasonic synthesis process. The particles of 30% APTMS-MMT_US (MMT modified with 30wt% APTMS with ultrasonic synthesis process) had a z-average diameter of about 500nm and a polydispersity index of 0.2. The resultant 30% APTMS-MMT_US was dispersed uniformly and stably in water. The poly(acrylic acid) (PAA)/APTMS-MMT multilayer films were grown through layer-by-layer (LBL) deposition of PAA and APTMS-MMT. SEM results indicated that the ultrasonic synthesis of APTMS-MMT increased dispersability of clay sheets at high loadings. The thermal stability and mechanical properties of PAA/APTMS-MMT composites were investigated by TGA and tensile test respectively. The results showed the ultrasonic synthesis of APTMS-MMT enhanced the thermal stability and mechanical properties of PAA/APTMS-MMT composites significantly. PAA/30% APTMS-MMT_US composite displayed 3 times higher strength and 6 times higher Young's modulus when compared with pure PAA polymer.

Keywords: Montmorillonite; LBL assembly; Composites; Ultrasonic

Supercritical carbon dioxide-assisted preparation of palladium nanoparticles on cyclotriphosphazene-containing polymer nanospheres by Jianwei Fu; Minghuan Wang; Shitao Wang; Xuzhe Wang; Hongfang Wang; Lei Hu; Qun Xu (pp. 7129-7133).

Display Omitted► PZS nanospheres as metal nanoparticle stabilizer were synthesized facilely. ► PdCl₂ was reduced in situ by ethanol in the condition of SC CO₂. ► Pd nanoparticle size on the PZS nanoparticles could be controlled.Poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) nanospheres with average diameter of 410nm were synthesized rapidly at room temperature and then homogeneously decorated with Pd nanoparticles through an inorganic reaction in supercritical carbon dioxide–ethanol solution using PdCl₂ as a metal precursor. The resultant Pd/PZS nanocomposites were morphologically and structurally characterized by means of scanning electron microscopy, transmission electron microscope equipped with energy-dispersive X-ray spectroscopy, and X-ray diffraction techniques. Characterization results showed that the Pd nanoparticles with good dispersibility could be well anchored onto the surfaces of the PZS nanospheres and the size of Pd nanoparticles could be controlled easily by varying the ethanol-reduction time.

Keywords: Deposition; Supercritical carbon dioxide; Nanocomposites; Polymer; Cyclotriphosphazene

The corrosion properties of phosphate coating on AZ31 magnesium alloy: The effect of sodium dodecyl sulfate (SDS) as an eco-friendly accelerating agent by R. Amini; A.A. Sarabi (pp. 7134-7139).

► SDS is used as an accelerating agent instead of sodium nitrite in phosphating bath. ► Using SDS, the corrosion resistance of phosphate coating was considerably increased. ► Using SDS, the rate of phosphate coating precipitation on Mg alloy was increased. ► Using SDS, phosphate coating with denser structure was produced.Sodium nitrite has been used as an accelerating agent in phosphating bath to improve its properties. However, it is well known that sodium nitrite is a carcinogenic component in phosphating sludge. In this study, it has been aimed to replace sodium nitrite by an environmentally friendly accelerating agent. To this end, sodium dodecyl sulfate (SDS) was used in phosphating bath to improve the phosphate coating formation on an AZ31 magnesium alloy. The effect of SDS/sodium nitrite ratio on the phosphated samples properties was also studied. Using field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), direct current (DC) polarization and electrochemical impedance spectroscopy (EIS) the properties of phosphated magnesium samples were studied.Results showed uniform phosphate coating formation on the magnesium sample mostly in hopeite phase composition. In addition, a denser and less permeable coating can be obtained at these conditions. The corrosion resistance of the phosphated samples was superiorly improved using higher SDS concentration in the phosphating bath.

Keywords: AZ31 magnesium alloy; Corrosion; Phosphate coating; Polarization; Sodium dodecyl sulfate

Molecular dynamics study of void effect on nanoimprint of single crystal aluminum by Ying Yuan; Tao Sun; Junjie Zhang; Yongda Yan (pp. 7140-7144).

► Deformation mechanism of nanoimprint of Al thin film containing void is investigated by atomistic simulation. ► Void lowers critical force for initial dislocation nucleation, while hinders dislocation motion. ► Strong influence of void volume fraction on nanoimprint process. ► Critical void volume fraction for minimum degree of spring back is found.Pre-existing defects can alter mechanical behavior of materials significantly under applied load. In current study molecular dynamics (MD) simulations are performed to reveal pre-existing void effect on nanoimprint of single crystal Al thin films, such as deformation mechanism and spring back phenomenon. Current simulation results show void acts as strong barrier to dislocation motion, although plastic deformation is dominantly controlled by dislocation activities. It indicates the void volume fraction has strong influence on nanoimprint: the larger the void volume fraction, the smaller the maximum force required for initial dislocation nucleation, and the stronger the interaction between extended dislocation and void. It also demonstrates that there is a critical void volume fraction for minimum spring back, which is resulted from competition between two roles affecting dislocation annihilation.

Keywords: Nanoimprint; Molecular dynamics; Void volume fraction; Spring back

Energy transfer from benzoic acid to lanthanide ions in benzoic acid-functionalized lanthanide-doped CaF₂ nanoparticles by Jianshe Wang; Zongwu Wang; Xia Li; Si Wang; Huadan Mao; Zhongjun Li (pp. 7145-7149).

This article demonstrates that the capped benzoic acid can efficiently sensitize the emission of Eu³⁺ and Tb³⁺ doped in CaF₂ nanoparticles.The preparation of benzoic acid-functionalized CaF₂:Ln³⁺ (Ln=Eu or Tb) nanoparticles and their sensitized luminescence are described in this report. First, to achieve sufficient proof for energy transfer from benzoic acid (BA) to lanthanide ions doped in nanoparticles, we employ Eu³⁺ as the microscopic probe and investigate the luminescent spectra of benzoic acid-functionalized CaF₂:Eu³⁺ (BA-CaF₂:Eu³⁺) nanoparticles. Next, to further reveal the difference between sensitized luminescence and common luminescence for Eu³⁺ doped in CaF₂ nanoparticles, we study the emission spectra of BA-CaF₂:Eu³⁺ nanoparticles excited at 286nm and 397nm, respectively. Finally, we analyze and compare the luminescent spectra of BA-CaF₂:Tb³⁺ and CaF₂:Ce³⁺, Tb³⁺ nanoparticles in detail. Our results indicate that both Eu³⁺ and Tb³⁺ doped in CaF₂ nanoparticles can be efficiently sensitized through benzoic acid.

Keywords: Key words; Sensitized emission; CaF; ₂; Benzoic acid; Nanoparticle

Self-assembled silver nanoparticle films at an air–liquid interface and their applications in SERS and electrochemistry by Li Wang; Yujing Sun; Guangbo Che; Zhuang Li (pp. 7150-7155).

Display Omitted► We report a novel technology to prepare Ag nanoparticle films at air–liquid interface. ► The morphology of films could be controlled by systematic variation of the experimental parameters. ► The as-prepared films show excellent SERS and electrocatalytic activity. ► The films have potential application in fuel cells, sensors and nanodevices design.In this paper, we present a novel technique to prepare silver nanoparticle films by controlling the self-assembly of nanoparticles at an air–liquid interface. In an ethanol–water phase, silver nanoparticles were prepared by reduction of AgNO₃ aqueous solution with NaBH₄ in the presence of cinnamic acid. It was found that the silver nanoparticles in this process could be trapped at the air–liquid interface to form 2-dimensional nanoparticle films. The morphology of nanoparticle films could be controlled by systematic variation of the experimental parameters. It is worth noting that the nanoparticle films could serve as the active substrates for surface-enhanced Raman scattering (SERS). 4-Aminothiophenol (4-ATP) molecule was used as a test probe to investigate the SERS sensitivity of different nanoparticle films. The results indicated that the nanoparticle films showed excellent Raman enhancement effect. Furthermore, the nanoparticle films prepared by our strategy were found to be efficient electrocatalysts for anodic oxidation of formaldehyde in alkaline medium.

Keywords: Assembly; Nanoparticle films; Interface; SERS; Electrochemistry

Luminescent properties of ZnO thin films treated by pulse-modulated high-power inductively coupled plasma by J.B. Wang; Z.S. Hu; X.L. Zhong; Y.J. Zhang; T. Ishigaki; T. Sekiguchi (pp. 7156-7159).

► An ultrasonic spray assisted chemical vapor deposition (spray-CVD) method was developed to deposit ZnO thin films. ► The effect of hydrogen plasma irradiation on luminescence properties of ZnO thin films was studied by using a pulse-modulated inductively coupled plasma technique. ► UV emission of ZnO thin films can be greatly enhanced by hydrogen plasma irradiation with appropriate irradiation conditions because non-radiative centers are passivated by H.The effect of hydrogen plasma irradiation on luminescence properties of ZnO thin films was studied by using a pulse-modulated inductively coupled plasma technique. H-plasma exposure distance was changed to investigate the effect of hydrogen plasma irradiation on luminescent properties. Room temperature cathodoluminescence (CL) spectrum shows that hydrogen plasma irradiation can increase the efficiency of UV emission at 3.27eV, and the improvement is strongly dependent on H-plasma exposure distance. For low temperature CL spectra, the intensity of donor–acceptor pair (DAP) transition at 3.315eV has been increased more rapidly after hydrogen plasma irradiation, leading DAP to be the dominant transition.

Keywords: Hydrogenation; Cathodoluminescence

In-depth characterization and computational 3D reconstruction of flagellar filament protein layer structure based on in situ spectroscopic ellipsometry measurements by Peter Kozma; Daniel Kozma; Andrea Nemeth; Hajnalka Jankovics; Sandor Kurunczi; Robert Horvath; Ferenc Vonderviszt; Miklos Fried; Peter Petrik (pp. 7160-7166).

► Flagellar filaments were immobilized onto Ta₂O₅ substrates in flow-cell. ► The surface was monitored in situ with spectroscopic ellipsometry. ► New optical model was developed for the characterization of the filamentous layers. ► The depth profile of protein mass density was determined. ► The statistical 3D structure of the filamentous layer was reconstructed.In this study, we have reconstructed the statistical 3D structure of hundreds of nanometers thick surface immobilized flagellar filament protein layers in their native environment, in buffer solution. The protein deposition onto the surface activated Ta₂O₅ film was performed in a flow cell, and the immobilization process was followed by in situ spectroscopic ellipsometry. A multilayer optical model was developed, in that the protein layer was described by five effective medium sublayers. Applying this method, an in-depth analysis of the protein layer formation was performed. Based on the kinetics in the distribution of the surface mass density, the statistical properties of the filamentous film could be determined computationally as a function of the measurement time. It was also demonstrated that the 3D structure of the protein layer can be reconstructed based on the calculated in-depth mass density profile. The computational investigation revealed that the filaments can be classified into two individual groups in approximately equal ratio according to their orientation. In the first group the filaments are close to laying position, whereas in the second group they are in a standing position, resulting in a significantly denser sublayer close to the substrate than at a larger distance.

Keywords: Spectroscopic ellipsometry; In-depth distribution; Protein layer structure; In situ process control; Mass density profile; 3D layer structure reconstruction

Enhanced luminescence and degradation resistance in Tb modified Yttrium Borate core–nano silica shell phosphor under UV and VUV excitation by Santa Chawla; Ravishanker; A.F. Khan; Ashish Yadav; H. Chander; V. Shanker (pp. 7167-7171).

► Intense green emitting YTb_xBO₃ phosphor developed in optimized reaction conditions. ► Thermal degradation completely arrested by capping with silica nanoparticles. ► Shorter decay time (4ms) achieved compared to commercially used green ZSM phosphor. ► Novelty of the work is in achieving high luminescence efficiency in the YBT system. ► Degradation resistant monochromatic green phosphor for PDP, Xe lighting developed.Composition variation in optimized solid state reaction conditions has been done to achieve intense green emission in YTb_xBO₃ phosphor under UV and VUV (147nm resonant Xe*, 172nm Xe₂* excimer band) excitation. Inert interface layer created by fabricating a shell of silica nanoparticles over individual phosphor grain protected the phosphor surface from deterioration and oxidation of luminescent ion (Tb³⁺) thus completely arresting phosphor degradation. At optimum Tb content of 20mol%, integrated photoluminescence intensity of developed YTb_xBO₃ phosphor is four times higher than commercial green YBT. With short decay time of 4ms, YTb_xBO₃ core–nano silica shell green emitting phosphor has great application potential in PDP panel and phosphor coated Xe lamps.

Keywords: Phosphor; Solid state reaction and capping; HRTEM; Photoluminescence properties; Time resolved decay

Structure and properties of (AlCrMnMoNiZrB_0.1)N_x coatings prepared by reactive DC sputtering by B. Ren; Z.X. Liu; L. Shi; B. Cai; M.X. Wang (pp. 7172-7178).

► R_N is N₂-to-Ar flow ratios, which effect on the structure and properties of films. ► Amorphous and FCC structures can be achieved at low R_N and high R_N, respectively. ► Solid solution strengthening and lattice strain enhanced the hardness of films. ► The nitride film deposited at R_N=0.5 has a friction coefficient of 0.12. ► Adhesive wear is the dominant wear mechanism in the films.The microstructure and properties of AlCrMnMoNiZrB_0.1 nitride films prepared by reactive direct current sputtering at various N₂-to-Ar flow ratios ( R_N) were investigated. The films had an amorphous structure at low R_N and a face-centered cubic structure at a high R_N. As the R_N increased, the decrease in clusters and defects resulted in a dense columnar structure and low surface roughness. The peak hardness and modulus of the nitride films were 10.3 and 180GPa, respectively. The enhanced hardness is ascribed to the increased metal–nitrogen bonding, solid solution strengthening of several metallic nitrides, and lattice strain. The nitride films deposited at R_N=0.2, 0.5, and 0.8 had friction coefficients of 0.16, 0.12 and 0.15, respectively. Wear-out failure occurred within 400s when R_N=0 and 1.0. Adhesive wear was the dominant wear mechanism.

Keywords: High-entropy alloy; Nitride film; Hardness; Friction coefficient; Adhesive wear

Photocatalytic and superhydrophilicity properties of N-doped TiO₂ nanothin films by M. Chekini; M.R. Mohammadizadeh; S.M. Vaez Allaei (pp. 7179-7183).

► Optical band gap of N doped TiO₂ was measured 0.18 eV less than the pure TiO₂ thin film. ► The doping leads to a decrease in roughness of the samples from 4 nm (TiO₂) to 1 nm (N-TiO₂). ► N-TiO₂ sample has more preferable hydrophilicity and photocatalytic properties rather than TiO₂.Pure TiO₂ and nitrogen doped titanium dioxide (N-TiO₂) thin films were prepared by sol–gel method through spin coating on soda lime glass substrates. TiCl₄ and urea were used as Ti and N sources in the sol. XRD results showed nitrogen doping has retarded anatase to rutile phase transformation. The doping also leads to a decrease in roughness of the samples from 4nm (TiO₂) to 1nm (N-TiO₂). However, surface analysis by statistical methods reveals that both surfaces have self-affine structure. Optical band gap of thin films was shifted from 3.65eV (TiO₂) to 3.47eV (N-TiO₂). Hydrophilic conversion and photocatalytic degradation properties of thin films were investigated and exhibited that N-TiO₂ thin film has more preferable hydrophilicity and photocatalytic properties under UV illumination.

Keywords: PACS; 61.72.U-; 81.16.Be; 82.65.+r; 82.30.RsSol–gel; N-doped TiO; ₂; thin film; Spin coating; Hydrophilic; Photocatalytic

Field emission studies of silver nanoparticles synthesized by electron cyclotron resonance plasma by Vishwas Purohit; Baishakhi Mazumder; A.B. Bhise; Pankaj Poddar; D.S. Joag; S.V. Bhoraskar (pp. 7184-7189).

Display Omitted► 3D deposition of silver nanoparticles by hollow cathode sputtering. ► Field emission studied on blunt tungsten tip. ► Effective way of tailoring particle sizes on a circular substrate.Field emission has been studied for silver nanoparticles (25–200nm), deposited within a cylindrical silver target in an electron cyclotron resonance (ECR) plasma. Particle size distribution was controlled by optimum biasing voltages between the chamber and the target. Presence of non-oxidized silver was confirmed from the X-Ray diffraction analysis; however, thin protective layer of oxide was identified from the selective area electron diffraction pattern obtained with transmission electron microscopy. The silver nanoparticles were seen to exhibit hilly pointed like structures when viewed under the atomic force microscopy (AFM). The emissive properties of these particles were investigated by field emission microscopy. It is found that this technique of deposition is ideal for formation of nanoparticles films on different substrate geometries with size controllability as well as its application to emission devices.

Keywords: Cold plasma; Nanoparticles; Field emission; Thin film

Electropolishing for the formation of anodic nanotubular TiO₂ with uniform length and density by Byung Gun Lee; Sung-Yu Hong; Jeong Eun Yoo; Jinsub Choi (pp. 7190-7194).

Display Omitted► Non-toxic alcohol based electrolyte is used for the electropolishing for the formation of anodic titanium oxide. ► The surface roughness on a large area is dramatically improved if electropolishing is employed before anodization of Ti. ► Anodization of polished Ti leads to the formation of nanotubular TiO₂ structures with more uniform length and relatively time-independent density of nanotubes compared to that prepared with anodization of non-polished Ti.Electropolishing of Ti was carried out in alcohol-based electrolyte and subsequently the polished Ti was anodized in ethylene glycol containing 0.25wt% NH₄F. Anodization of polished and non-polished Ti, respectively, showed no big difference in the degree of local arrangement of the nanotubes, whereas the surface roughness on a large area was dramatically improved in the anodized polished Ti. Anodization of polished Ti leads to the formation of nanotubular TiO₂ structures with more uniform length and relatively time-independent density of nanotubes compared to that prepared with anodization of non-polished Ti, meaning that electropolishing is indispensable for the formation of uniform nanotubular TiO₂ structures.

Keywords: Electropolishing; Anodization; Valve metals; Titanium oxide

Characterization at a local scale of a laser-shock peened aluminum alloy surface by B. Rouleau; P. Peyre; J. Breuils; H. Pelletier; T. Baudin; F. Brisset (pp. 7195-7203).

► The paper investigates mechanical surface states and surface potential modifications induced by Laser Shock Processing (LSP) on a 2050-T8 aluminum alloy. ► Local techniques (EBSD, nanoindentation, SKPFM) are used. ► Little metallurgical and work-hardening effects are obtained after LSP. ► LSP reduces inclusion-matrix surface potential gradients due to compressive surface stresses.The influence of a laser shock peening mechanical surface treatment on 2050-T8 aluminum alloy has been investigated, mostly using Scanning Kelvin Probe Force Microscopy. Volta potential difference maps around Al(CuFeMn) precipitates were performed before and after laser-shock peening to determine the influence of laser treatment versus galvanic coupling near precipitates, and resulting pit initiations. It has been shown that laser shock peening either preserves or reduces precipitate-matrix Volta potentials gradients, which in this later case, and correlated to recent corrosion electrochemical investigations, could explain corrosion improvement obtained after laser-shock peening treatments of aluminum alloys. The influence of crystal orientation and plastic deformation, and more specifically the effect of laser-induced compressive residual stresses or work-hardening, on the Volta potential values and on the pitting corrosion behavior was also addressed.

Keywords: Aluminum alloy; Laser-shock peening; Scanning Kelvin Probe Force Microscopy; Work function; Deformation

Mechanical and optoelectric properties of post-annealed fluorine-doped tin oxide films by ultraviolet laser irradiation by Shih-Feng Tseng; Wen-Tse Hsiao; Donyau Chiang; Kuo-Cheng Huang; Chang-Pin Chou (pp. 7204-7209).

► The FTO thin films were deposited on the soda–lime glass substrates by the sputtering method. An oxide buffer layer of SiO₂ composition was deposited on glass substrate surface to enhance adhesion between the FTO film and substrate. ► The fluorine-doped tin oxide (FTO) thin films deposited on a soda–lime glass substrate was annealed by a defocus ultraviolet (UV) laser irradiation at ambient temperature. ► After laser irradiations using the various laser processing parameters, the post-annealed FTO films had different mechanical and optoelectric properties. ► The microhardness and reduced modulus of the annealed films were evaluated by a nanoindentation instrument. ► In addition, the transmittance spectra and sheet resistance of the annealed films were analyzed by a spectrophotometer and a four point probe instrument, respectively.The fluorine-doped tin oxide (FTO) thin film deposited on a soda–lime glass substrate was annealed by a defocus ultraviolet (UV) laser irradiation at ambient temperature. The mechanical and optoelectric properties of FTO films annealed by using the various laser processing parameters were reported. After the FTO films were subjected to laser post-annealing, the microhardness were slightly less but the reduced modulus values were larger than that of unannealed FTO films, respectively. The average optical transmittance in the visible waveband slightly increased with increasing the laser annealing energy and scan speed. Moreover, all the sheet resistance of laser annealed films was less than that of the unannealed ones. We found that the sheet resistance decrease was obviously influenced by annealing. The suitable annealing conditions could maintain the film thickness and relief the internal stress generated in the film preparation process to improve the electrical conductivity via decreasing laser energy or increasing scan speed.

Keywords: Fluorine-doped tin oxide (FTO); UV laser irradiation; Post-annealing; Mechanical property; Optoelectric property

High performance nanostructured ZrO₂ based thermal barrier coatings deposited by high efficiency supersonic plasma spraying by Y. Bai; Z.H. Han; H.Q. Li; C. Xu; Y.L. Xu; Z. Wang; C.H. Ding; J.F. Yang (pp. 7210-7216).

► Nanostructured YSZ coating was deposited by supersonic atmospheric plasma spraying. ► The coating was composed of unmelted nanoparticles and nanograins formed from melt. ► The effect of nanostructure on the properties of SAPS-coating was studied.In this paper, the nanostructured zirconia (ZrO₂) based thermal barrier coatings (TBCs) deposited by high efficiency supersonic atmospheric plasma spraying (SAPS), were described. The phase composition, microstructure, thermal conductivity and thermal shock resistance of as-sprayed coating were studied. The results revealed that the as-sprayed coating was composed of tetragonal zirconia and consisted of some unmelted nanoparticles (30–50nm) and nanograins (60–110nm), and the latter was the main microstructure of the coating. The nanograins and homogeneously distributed micro-cracks of coating resulted in not only low thermal conductivity, but also high thermal cycling lives. Besides, the failure process of coating during thermal cycles was also investigated in the present work.

Keywords: Nanoparticles; Nanograins; Zirconia; Thermal conductivity; Thermal shock resistance

The influence of substrate etched on the quality of GaN epilayers by Junping Mei; Xinjian Xie; Qiuyan Hao; Weina Jing; Caichi Liu (pp. 7217-7220).

► Sapphire substrate is etched by H₃PO₄ and NaOH. ► The Raman scattering spectroscopy and photoetching analyses show that the substrate etched can effectively decrease the residual stress and the dislocations density in these epilayers. ► The X-ray diffraction analysis shows the process can reduce the value of the FWHM.We report the growth of GaN epilayers on the sapphire substrate etched by MOCVD. Sapphire substrate is etched by H₃PO₄ and NaOH. The Raman scattering spectroscopy and photoetching analyses show that the substrate etched can effectively decrease the residual stress and the dislocations density in these epilayers. The X-ray diffraction analysis shows the process can reduce the value of the FWHM. Therefore, the quality of GaN epilayers should be improved by substrate etched.

Keywords: GaN epilayers; Strain; X-ray diffraction; Raman scattering

Structure and refractive index dispersive behavior of potassium niobate tantalate films prepared by pulsed laser deposition by Wenlong Yang; Zhongxiang Zhou; Bin Yang; Yongyuan Jiang; Hao Tian; Dewei Gong; Hongguo Sun; Wen Chen (pp. 7221-7225).

► Pure perovskite phase and crack-free KTa_0.5Nb_0.5O₃ thin films prepared by PLD. ► Slight surface roughness with a uniform densely packed microstructure. ► Relation between refractive index dispersive behavior and ABO₃ structure BO₆ oxygen octahedron. ► Dispersive parameter E₀/ S₀ from single term Sellmeier oscillator approximation is 6.72±0.04×10⁻¹⁴eVm².Pure perovskite phase and crack-free KTa_0.5Nb_0.5O₃ thin films were prepared on Pt/Ti/SiO₂/Si substrates by pulsed laser deposition. The structure and orientation were analyzed by X-ray diffraction. The optical properties were investigated by an ellipsometer. The relationship between the refractive index dispersive behavior and internal structure was analyzed by Sellmeier dispersion model and single electronic oscillator approximation. The parameters of room temperature monomial Sellmeier oscillator were calculated. And the refractive index dispersive parameter E₀/ S₀ of KTa_0.5Nb_0.5O₃ thin films on Pt/Ti/SiO₂/Si substrates is (6.72±0.04)×10⁻¹⁴eVm², which is consistent with those of KTN crystals and compounds with ABO₃ perovskite type structure.

Keywords: Potassium niobate tantalate film; Pulsed laser deposition; Structure; Refractive index dispersion; Sellmeier oscillator approximation

Mn⁴⁺:BiFeO₃/Zn²⁺:BiFeO₃ bilayered thin films of (111) orientation by Jiagang Wu; John Wang; Dingquan Xiao; Jianguo Zhu (pp. 7226-7230).

► (111) orientation for BiFe_0.95Mn_0.05O₃/BiFe_0.95Zn_0.05O_3. ► Low leakage current and improved fatigue endurance. ► A larger remanent polarization of 2 P_r∼161.0 μC/cm².Ferroelectric and fatigue behavior of bilayered thin films consisting of Mn⁴⁺-modified BiFeO₃ and Zn²⁺-modified BiFeO₃, which were deposited on SrRuO₃-buffered Pt coated silicon substrates, were systematically investigated. The (111) orientation is induced for the BiFe_0.95Mn_0.05O₃/BiFe_0.95Zn_0.05O₃ bilayer, due to the introduction of the bottom BiFe_0.95Zn_0.05O₃ layer. With increasing the thickness ratio of the BiFe_0.95Mn_0.05O₃ layer, their leakage current decreases, and the fatigue endurance is greatly improved owing to the introduction of the BiFe_0.95Mn_0.05O₃ layer with a lower fatigue rate. The BiFe_0.95Mn_0.05O₃/BiFe_0.95Zn_0.05O₃ bilayer with the thickness ratio of 3:1 exhibits a larger remanent polarization of 2 P_r∼161.0μC/cm² than those of bilayers with different thickness ratios, while their coercive field slightly increases with increasing the thickness ratio of the BiFe_0.95Mn_0.05O₃ layer.

Keywords: BiFeO; ₃; Bilayered structure; Ferroelectric properties; Fatigue behavior

Photoluminescent zinc oxide polymer nanocomposites fabricated using picosecond laser ablation in an organic solvent by Philipp Wagener; Shamsolzaman Faramarzi; Andreas Schwenke; Rupert Rosenfeld; Stephan Barcikowski (pp. 7231-7237).

Display Omitted► We ablated zinc in a polyurethane-doped tetrahydrofuran solution by picosecond laser pulses. ► As reaction product zinc oxide-polymer nanocomposites are formed. ► The nanocomposites consist of an oxidized and crystalline ZnO core and a polymer shell. ► The use of tetrahydrofuran as solvent enables the use of polar or semi-polar polymer. ► The laser-generated nanocomposites show green photolumiscence due to oxygen defects.Nanocomposites made of ZnO nanoparticles dispersed in thermoplastic polyurethane were synthesized using picosecond laser ablation of zinc in a polymer-doped solution of tetrahydrofuran. The pre-added polymer stabilizes the ZnO nanoparticles in situ during laser ablation by forming a polymer shell around the nanoparticles. This close-contact polymer shell has a layer thickness up to 30nm. Analysis of ZnO polyurethane nanocomposites using optical spectroscopy, high resolution transmission electron microscopy and X-ray diffraction revealed that oxidized and crystalline ZnO nanoparticles were produced. Those nanocomposites showed a green photoluminescence emission centred at 538nm after excitation at 350nm, which should be attributed to oxygen defects generated during the laser formation mechanism of the monocrystalline nanoparticles. Further, the influence of pulse energy and polymer concentration on the production rate, laser fluence and energy-specific mass productivity was investigated.

Keywords: Nanohybrids; Zinc oxide nanoparticles; Photoluminescence emission; Polymer nanocomposite; Laser fluence; Production rate

Characterization of coating probe with Ti-DLC for electrical scanning probe microscope by Xiaolei Shia; Liqiu Guo; Yang Bai; Lijie Qiao (pp. 7238-7244).

► We investigate the characterization of Ti doped diamond-like-carbon (DLC) as coating material on a silicon cantilever for ESPM. ► We deposited a layer of Ti-DLC thin film on the surface of Si cantilever by magnetron sputtering. ► The electric conductivity and the scanning image quality of the Ti-DLC-coated probes were the same as the commercial conductive probes, while the wear resistance and service life was significantly better.In electrical scanning probe microscope (ESPM) applications, the wear and conductivity of the probe are undoubtedly serious concerns since they affect the integrity of the measurements. This study investigates the characterization of Ti doped diamond-like-carbon (DLC) as coating material on a silicon cantilever for ESPM. We deposited a layer of Ti-DLC thin film on the surface of Si cantilever by magnetron sputtering. The morphology and composition of the Ti-DLC films were characterized by scanning electron microscopy and Raman spectroscopy, respectively. We also compared the wear resistance, electric conductivity and scanning image quality of the Ti-DLC-coated probes with those of commercially available conductive probes. The results showed that the electric conductivity and the scanning image quality of the Ti-DLC-coated probes were the same as the commercial conductive probes, while the wear resistance and service life was significantly better.

Keywords: Probe; Ti-DLC films; Magnetron sputtering; Wear resistance; Electrical conductivity

Dielectric and relaxation properties of thermally evaporated nanostructured bismuth sulfide thin films by K. Mageshwari; R. Sathyamoorthy; P. Sudhagar; Yong Soo Kang (pp. 7245-7253).

► Understanding the electrical properties of semiconducting thin films is essential in device fabrication. In this study, we employed dielectric and relaxation analysis of nanocrystalline bismuth sulphide thin films. ► The information about the conduction of free charges under the application of an external electric field was explored using Al/BiSnc/Al structures. ► The inter-relationship between optical band gap energy and conduction properties of BiS thin films was explored. ► AC conductivity showed that the correlated barrier hopping model is the appropriate mechanism for the electron transport of BiS films. ► The results discussed in this report with necessary basic theoretical models were highly informative for understand the electrical properties of semiconducting thin films.Nanostructured bismuth sulfide thin films were prepared onto glass substrates with particle size of 21nm by thermal evaporation using readily prepared bismuth sulfide nanocrystallite powder. The X-ray diffraction pattern revealed that bismuth sulfide thin films exhibit orthorhombic structure. The existence of quantum confinement effect was confirmed from the observed band gap energy of 1.86eV. AC and DC electrical conductivity of Al/BiSnc/Al structures was investigated in the frequency range 0.5–100kHz at different temperatures (303–463K) under vacuum. The AC conductivity ( σ_ac) is found to be proportional to angular frequency ( ω^s). The obtained experimental result of the AC conductivity showed that the correlated barrier hopping model is the appropriate mechanism for the electron transport in the nanostructured bismuth sulfide thin films. DC conduction mechanism in these films was studied and possible conduction mechanism in the bismuth sulfide thin films was discussed.

Keywords: Semiconductor; Thin film; Bismuth sulfide; Dielectric property; Relaxation property

Microstructure and shear fracture characteristics of porous anodic TiO₂ layer before and after hot water treatment by Z.X. Chen; W.X. Wang; Y. Takao; T. Matsubara; L.M. Ren (pp. 7254-7262).

► Water treatment of anodic TiO₂ results in nano-sized and well-crystallized oxides. ► Before treatment, shear fracture occurs primarily within cavity-containing layer. ► After treatment, shear fracture occurs along bottom surface of nanostructured layer. ► After treatment, shear strength of anodic TiO₂ layer decreases obviously.Porous TiO₂ layer was fabricated on the surface of commercially pure titanium using an anodic spark oxidation technique for biomedical application, and subsequent hot water treatment was performed to modify the resultant oxide layer. The microstructure features and shear fracture characteristics of anodic oxide layer before and after water treatment were investigated. Results show that before water treatment, the oxide layer exhibited a porous surface with few nanometer features and consisted of poorly crystallized oxides, and an inner layer containing numerous cavities was observed near the oxide–substrate interface. After water treatment, the crystallinity degree of oxide layer was increased significantly and a nanostructured surface layer was obtained. The shear fracture characteristics of oxide layer were greatly influenced by its microstructure features. Before water treatment, the shear fracture took place primarily within the cavity-containing layer, resulting in a pitted fracture surface on the substrate side. However, after water treatment, the shear fracture occurred mainly along the bottom surface of nanostructured surface layer and the shear strength of oxide layer decreased obviously.

Keywords: Titanium; Anodic spark oxidation; Hot water treatment; Microstructure; Fracture

CO₂ laser assisted removal of UO₂ and ThO₂ particulates from metal surface by Aniruddha Kumar; J.P. Nilaya; D.J. Biswas; R.B. Bhatt; Mohd. Afzal; J.P. Panakkal; H.S. Kamath (pp. 7263-7267).

► Pulsed laser irradiation can remove radioactive particulates from metal surface. ► Adhesion of ThO₂ particulates are more than UO₂ particulates. ► Threshold fluence to remove UO₂ particulates is less in comparison to ThO₂ particulates. ► Cleaning efficiency can be increased by choosing wave length, which is absorbing to particulates.Pulsed laser assisted removal of uranium dioxide and thorium dioxide particulates from stainless steel surface have been studied using a TEA CO₂ laser. Decontamination efficiency is measured as a function of laser fluence and number of pulses. Threshold fluence for the removal of UO₂ particulates has been found to be lower than that required for the removal ThO₂ particulates. Usage of a ZnSe substrate, that is transparent to the laser wavelength used here, enabled us to decouple the cleaning effect arising out of absorption in the particulates from that in the substrate and has contributed towards understanding the mechanism responsible for cleaning. The experimental observations are also corroborated by simple theoretical calculations.

Keywords: Decontamination; CO; ₂; laser; UO; ₂; ThO; ₂; Morphology

Investigation of the voltage and time effects on the formation of hydroxyapatite-containing titania prepared by plasma electrolytic oxidation on Ti–6Al–4V alloy and its corrosion behavior by M. Montazeri; C. Dehghanian; M. Shokouhfar; A. Baradaran (pp. 7268-7275).

► Formation of HA/TiO₂ coating on Ti–6Al–4V alloy may improve the corrosion behavior. ► Effect of voltage and time on PEO process for HA formation was investigated. ► For formation of HA phase with titania a voltage of 500V is needed. ► At 500V, the amount of HA phase increased with increasing the treatment time. ► The best corrosion behavior was observed for the sample coated at 500V and 15min.Producing titania and hydroxyapatite (HA) bioceramic coating on titanium alloys increases corrosion resistance and biocompatibility of these alloys. Plasma electrolytic oxidation (PEO) is one of the effective techniques for producing this type of coating. This method produces coatings with enough thickness and appropriate adhesion. In this study, titania and HA were directly produced on Ti–6Al–4V by applying PEO process in a Ca- and P-containing electrolyte by changing voltage and time parameters. Morphology and cross section, chemical composition and elements of coatings were investigated by scanning electron microscope, X-ray diffraction and energy dispersive spectroscopy, respectively. Corrosion behavior of the samples was also examined by potentiodynamic polarization and electrochemical impedance spectroscopy. The results indicated that the formation of HA phase with titania needs a minimum voltage below which HA is not formed. By increasing the operation time, the amount of the formed HA increased. Also, the sample coated at 500V and 15min showed the best corrosion behavior in Ringer's solution.

Keywords: Plasma electrolytic oxidation; Ti–6Al–4V; Hydroxyapatite; Corrosion resistance

The preparation of vanadium-doped TiO₂–montmorillonite nanocomposites and the photodegradation of sulforhodamine B under visible light irradiation by Ke Chen; Jingyi Li; Wenxi Wang; Yumin Zhang; Xiaojing Wang; Haiquan Su (pp. 7276-7285).

► The different Ti/MMT ratios exerted a great influence on microstructures of the catalysts and their photocatalytic activities. ► The average sizes of V-TiO₂-MMT were smaller than those of pure TiO₂ and V-TiO₂. ► V-TiO₂-MMT/120 (120 denotes Ti/MMT is 120 mmol/g.) and V-TiO₂-MMT/30 had relatively higher photocatalytic activity in comparison to the other catalysts.The photodegradation of sulforhodamine B on vanadium-doped TiO₂–montmorillonite (TiO₂–MMT) nanocomposites was investigated under visible light irradiation. V-TiO₂–MMT nanocomposites with different amounts of MMT were prepared by a sol–gel process. The microstructure and properties of V-TiO₂–MMT were characterized by XRD, TEM, XPS, DRS, nitrogen adsorption isotherms, and FTIR. These analytic results indicated that the different Ti/MMT ratios exerted a great influence on their microstructures and their photocatalytic activities. The average sizes of V-TiO₂–MMT were smaller than those of pure TiO₂ and V-TiO₂. And the layered structure of MMT was completely destroyed in the V-TiO₂–MMT with the relatively high ratio of Ti/MMT (240, 120, 80, 60mmol/g), but it retained the partial MMT layered structure and had an enlargement of some basal space of MMT in V-TiO₂–MMT with the relatively low ratio of Ti/MMT (30, 24mmol/g). V-TiO₂–MMT/120 (120 denotes the ratio of Ti/MMT is 120mmol/g. The names of other catalysts followed the same convention.) and V-TiO₂–MMT/30 had relatively higher photocatalytic activity in comparison to the others. Besides, in the preparation process, we selected V-TiO₂–MMT/120 using different washing media to examine the effect of washing medium on the photocatalytic activity. The result indicated that it was critical to choose a proper washing medium to obtain an optimal photocatalytic activity.

Keywords: Titanium-dioxide; Vanadium; Montmorillonite; Photocatalysis; Sulforhodamine B

Interfacial reaction and electrical characteristics of Cu(RuTaN_x) on GaAs: Annealing effects by W.K. Leau; J.P. Chu; C.H. Lin (pp. 7286-7290).

► Interfacial reaction of barrierless Cu(RuTaNx)/GaAs structure is clarified. ► The structure shows electrical rectifying properties upon annealing at 550°C. ► The formation of quasi ohmic contact is further confirmed by XRD, TEM and EDS.This study elucidates the thermal stability and quasi ohmic contact characteristics of Cu(RuTaN_x) fabricated on a barrierless GaAs substrate. Cu(RuTaN_x) was prepared by cosputtering Cu, Ta, Ru, and N. The resistivity of the Cu(RuTaN_x)/GaAs structure annealed at 500°C for 30min was lower than that of the as-deposited structure, and the former was thermally stable up to 500°C after 30min of annealing. Further, the Cu(RuTaN_x)/GaAs structure exhibited electrical rectifying properties upon annealing at 550°C for 10min and revealed a quasi ohmic contact, as determined by the circular transmission line model (CTLM). The formation of quasi ohmic contact is further confirmed by transmission electron microscopy and energy dispersive X-ray spectroscopy.

Keywords: Key words; Barrierless; GaAs; Cu(RuTaNx); Copper metallization; Quasi ohmic contact; CTLM

Direct creation of black silicon using femtosecond laser pulses by A.Y. Vorobyev; Chunlei Guo (pp. 7291-7294).

► Black silicon is produced by direct femtosecond laser surface structuring. ► In the visible, the reflectance of the blackened surface is less than 5%. ► Low reflectance of black silicon extends to mid-infrared wavelengths. ► Created black silicon is mechanically robust.Using a direct femtosecond laser surface structuring technique, an array of equally spaced parallel nanostructure-textured microgrooves on silicon was produced that causes a dramatic reduction of the treated silicon reflectance. The processed area appears velvet black at all viewing angles. Throughout the visible region, the reflectance of the blackened surface is less than 5%. The antireflection effect of the processed surface also extends to the mid-infrared wavelength range. Furthermore, this technique has a potential in reducing silicon reflectance at terahertz frequencies and even in millimeter wavelength range.

Keywords: PACS; 78.68.+m; 78.20.Ci; 78.40.Fy; 81.40.TvFemtosecond laser; Reflectance; Microstructures; Nanostructures; Silicon

Tungsten and iridium multilayered structure by DGP as ablation-resistance coatings for graphite by Wangping Wu; Zhaofeng Chen; Han Cheng; Liangbing Wang; Ying Zhang (pp. 7295-7304).

► Tungsten interlayer is used to enhance the adhesion of the iridium coating to the graphite substrate. ► A newly designed multilayer coating of tungsten/iridium is produced by double glow plasma onto graphite substrate. ► The coated graphite substrates are protected more effectively by W/Ir multilayer coating than Ir single-layer coating. ► The mass loss rate of the W/Ir-coated specimen is about 1.62%.Oxidation protection of carbon material under ultra-high temperature is a serious problem. In this paper, a newly designed multilayer coating of W/Ir was produced onto the graphite substrate by double glow plasma. As comparison, the Ir single-layer coating on the graphite was also prepared. The ablation property and thermal stability of the coatings were studied at 2000°C in an oxyacetylene torch flame. Ablation tests showed that the coated graphite substrates were protected more effectively by W/Ir multilayer coating than Ir single-layer coating. Ir single-layer coating after ablation kept the integrality, although there was a poor adhesion of the Ir coating to the graphite substrate because of the thermal expansion mismatch and the non-wetting of the carbon by Ir coating. The mass loss rate of the W/Ir-coated specimen after ablation was about 1.62%. The interface of W/Ir multilayer coating and the graphite substrate exhibited good adherence no evidence of delamination after ablation. W/Ir multilayer coating could be useful for protecting graphite in high-temperature application for a short time.

Keywords: Coating; Graphite; W/Ir; Ablation

Thermal stability of atomic-layer-deposited ultra-thin niobium oxide film on Si (100) by Yue Huang; Yan Xu; Shi-Jin Ding; Hong-Liang Lu; Qing-Qing Sun; David Wei Zhang; Zhenyi Chen (pp. 7305-7309).

► Ultra-thin Nb₂O₅ films with excellent uniformity have been grown on Si (100) by atomic-layer-deposition using Nb(OC₂H₅)₅ and H₂O precursors. ► The ultra-thin (∼3nm) Nb₂O₅ film is gradually built up into distributed large islands with increasing rapid thermal annealing (RTA) temperature. Both crystalline and amorphous phases are formed in the matrix of Nb₂O₅ annealed at 700°C. ► In terms of the as-prepared sample, an around 1.5nm interfacial layer (IL) is observed and composed of niobium silicate (Nb–O–Si). The high temperature RTA leads to a thickened IL, which is attributed to the formation of more Nb–O–Si bonds and new silicon oxide (Si–O–Si) adjacent to the Si (100).Ultra-thin Nb₂O₅ films with excellent uniformity have been grown on Si (100) by atomic-layer-deposition using Nb(OC₂H₅)₅ and H₂O precursors, and the corresponding thermal stability has been studied through atomic force microscope, transmission electron microscope and X-ray photoelectron spectroscopy. The results indicate that the ultra-thin (∼3nm) Nb₂O₅ film is gradually built up into distributed large islands with increasing rapid thermal annealing (RTA) temperature. Meanwhile, both crystalline and amorphous phases are formed in the matrix of Nb₂O₅ annealed at 700°C. In terms of the as-prepared sample, an interfacial layer (IL) with a thickness of around 1.5nm is observed, that is composed of niobium silicate (Nb–O–Si). Further, the high temperature RTA leads to a thickened IL, which is attributed to the formation of more Nb–O–Si bonds and new silicon oxide (Si–O–Si) adjacent to the Si (100).

Keywords: Ultra-thin film; Atomic-layer-deposited Nb; ₂; O; ₅; Thermal stability

An He-implanted optical planar waveguide in an Nd:YGG laser crystal preserving fluorescence properties by Jin-Hua Zhao; Qing Huang; Peng Liu; Xue-Lin Wang (pp. 7310-7313).

► The planar waveguide formed by the ion implantation method on the Nd:YGG crystal was investigated for the first time. ► The implantation processes had almost no influence on the absorption properties at the wavelength scale of w>550nm on account of the absorption spectrum. ► The microluminescence investigation reveals that, in the waveguide, the fluorescence properties of the Nd³⁺ ions and the energy transfer efficiency were not deteriorated by the helium implantation.We report the formation of a planar waveguide in an Nd:YGG laser crystal by low-energy He-ion implantation at liquid nitrogen temperature (77K). The optical properties are measured by the prism coupling and end-face coupling methods, the absorption properties the waveguide and Nd:YGG substrate are obtained. The fluorescence spectrums are investigated by confocal methods. The experimental results revealed that the planar waveguide preserved the absorption and fluorescence properties of the Nd:YGG laser crystal. Thus, the planar waveguide formed by the ion implantation method is a promising candidate in waveguide lasers.

Keywords: PACS; 33.50.Dq; 42.70.Hj; 42.82.Et; 61.80.JhNd:YGG; waveguide; ion implantation; fluorescence

Evolution of Zn based high purity phases under NH₃ gas atmosphere and their PL properties by Waheed S. Khan; Chuanbao Cao; Faheem K. Butt; Zulfiqar Ali; M. Safdar; Liqing Pan; M. Yasir Rafique; Qurrat ul Ain; Zahid Usman; Ghulam Nabi (pp. 7314-7319).

.Display Omitted► Highly pure Zn based phases like Zn₃N₂, ZnO and Zn microparticles prepared under NH₃ gas environment. ► Vapor–solid and self-catalytic processes based growth mechanisms are proposed for the products. ► PL spectra of the products exhibited very interesting and infrequently observed emission bands. ► Optical studies revealed the promise of the structures for applications in light emitting devices.We report here the evolution of zinc based high purity phases with novel morphologies such as Zn₃N₂ hollow structures, ZnO nanowires and nanopowders, as well as metallic Zn layered hexagonal microparticles at progressively increased reaction temperature of 600°C, 700°C, 800°C under NH₃ gas atmosphere using Zn powder precursor and keeping all other experimental parameters unchanged. Growth mechanism for Zn₃N₂ obtained by nitridation, ZnO by oxidation and Zn microparticles via thermal evaporation & condensation process are discussed briefly. The as-synthesized products were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM). Photoluminescence (PL) studies have revealed very interesting and infrequently observed emission bands at 378 and 661nm for Zn₃N₂, 359 and 396nm for ZnO as well as 389nm for Zn polyhedral microparticles.

Keywords: Zinc nitride; Zinc oxide; Zinc metal; Nanostructures; Growth mechanism; PL properties

Investigation of structure and magnetic properties of the as-deposited and post-annealed iron nitride films by reactive facing-target sputtering by X.P. Feng; W.B. Mi; H.L. Bai (pp. 7320-7325).

► Iron nitride films prepared by reactive facing-target sputtering ► N-rich phases are obtained in as-deposited films with the increase ofFN2. ► After being annealed, N-rich phases are decomposed and γ′-Fe₄N appears. ► Magnetic characteristics of films are dependent on variation valence states of Fe.Structure and magnetic properties of the as-deposited and post-annealed iron nitride films have been investigated systematically. A series of phases containing α-Fe, ɛ-Fe₃N, ξ-Fe₂N and γ″-FeN were obtained as nitrogen flow rate(FN2) increases from 0.5 to 30sccm. An increase of the nitrogen concentration in the as-deposited films could be concluded from the phase transition with the increasingFN2. After being annealed, some of the iron nitride phases are decomposed and γ′-Fe₄N appears in the films. The magnetic characteristics are dependent onFN2, which can be ascribed to the facts that the nitrogen in the films turns the valence states of Fe into Fe⁺ or Fe^dipole with high magnetic momentum or ever H-like bond Fe^+/dipole with low magnetic momentum based on the bond-band-barrier correlation mechanism.

Keywords: PACS; 75.50.Bb; 81.15.Cd; 61.72.Cc; 68.55.−a; 75.70.AkIron nitride; Sputtering; Annealing; Structure; Magnetic property

Self assembly of SiO₂-encapsulated carbon microsphere composites by Yongzhen Yang; Jingjing Song; Yanxing Han; Xingmei Guo; Xuguang Liu; Bingshe Xu (pp. 7326-7329).

.Display Omitted► CMS@SiO₂ composite films with ordered and dense structure were obtained by vertical deposition. ► The deposition temperature and suspension concentration influenced the quality of self-assembling film. ► The composite films grew steadily with increasing suspension concentration.SiO₂ was firstly coated onto the surface of carbon microspheres (CMSs) using tetraethyl orthosilicate (TEOS) as precursor by Stöber method. Then SiO₂-encapsulated CMS (CMS@SiO₂) composites were self-assembled by vertical deposition, in which the effects of deposition temperature and suspension concentration on the quality of self-assembling film were investigated. Morphologies and structures of the samples were characterized by field emission scanning electron microscopy, Fourier transformation infrared spectrometry, X-ray diffraction and thermogravimetry. The results show that uniform CMS@SiO₂ composites with good mono-dispersion were prepared by Stőber method with 0.5g of CMSs, 2mL of TEOS, 30mL of ammonia and 12h of reaction time, the CMSs-based films with ordered and denser structure were prepared by vertical deposition using CMS@SiO₂ composites as monodipersion spheres under suspension concentration of 1wt% and deposition temperature of 50°C. The ultraviolet-visible absorption measurement shows that the absorbance of CMS@SiO₂ composite films grew steadily with increasing suspension concentration.

Keywords: Carbon films; Carbon microspheres; Vertical deposition; Self-assembly

Low-temperature liquid phase deposited TiO₂ films on stainless steel for photogenerated cathodic protection applications by C.X. Lei; H. Zhou; Z.D. Feng; Y.F. Zhu; R.G. Du (pp. 7330-7334).

► Anatase TiO₂ films were obtained on 304SS without post-annealing treatment. ► The LPD-derived TiO₂ films were crack-free. ► The TiO₂ film exhibited an effective photogenerated cathodic protection for 304SS.The low-temperature synthesis of anatase TiO₂ films was an imperative requirement for their application to corrosion prevention of metals. In this paper, a liquid phase deposition (LPD) technique was developed to prepare TiO₂ films on SUS304 stainless steel (304SS) at a relatively low temperature (80°C). The as-prepared films were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photon spectroscopy (XPS). It was observed that a dense and crack-free anatase TiO₂ film with a thickness about 300nm was obtained. The film contained some fluorine and nitrogen elements, and the amounts of these impurities were greatly decreased upon calcination. Under the white light illumination, the electrode potential of TiO₂ coated 304SS rapidly shifted to a more negative direction. Moreover, the photopotential of TiO₂/304SS electrode showed more negative values with increased film thickness. In conclusion, the photogenerated cathodic protection of 304SS was achieved by the low-temperature LPD-derived TiO₂ film.

Keywords: Liquid phase deposition; TiO; ₂; film; Photogenerated cathodic protection

Doping mode, band structure and photocatalytic mechanism of B–N-codoped TiO₂ by Jixiang Yuan; Enjun Wang; Yongmei Chen; Wensheng Yang; Jianghong Yao; Yaan Cao (pp. 7335-7342).

. The interstitial N and [NOB] species and surface NO_x and B₂O₃ species on B–N-codoped TiO₂ resulted in the extended UV- and visible-light absorbance, the facilitated separation of photo generated charge carriers and thus the better photocatalytic performance.Display Omitted► B–N-codoped TiO₂ (B–N-TiO₂) photocatalysts showed a much higher photocatalytic activity than pure TiO₂, N-doped TiO₂ (N-TiO₂) and B-doped TiO₂ (B-TiO₂) under visible light irradiation. ► The doping mode, band structure and photocatalytic mechanism of B–N-TiO₂ photocatalysts were elucidated in detail based on both the Ti–O–B–O–Ti structure in the TiO₂ crystal lattice and the crystal structure of B-TiO₂ and B–N-TiO₂. ► The interstitial N and [NOB] species and surface NO_x and B₂O₃ species on B–N-TiO₂ resulted in the extended UV- and visible-light absorbance, the facilitated separation of photo generated charge carriers and thus the better photocatalytic performance.The photocatalyst B and N codoped TiO₂ (B–N-TiO₂) was prepared via the sol–gel method by using boric acid and ammonia as B and N precursors. The doping mode, band structure and photocatalytic mechanism of B–N-TiO₂ were investigated well and elucidated in detail. B–N-TiO₂ showed the narrowed band gap and thus extended the optical absorption due to interstitial N and [NOB] species in the TiO₂ crystal lattice. The coexistence of interstitial N and [NOB] species in the TiO₂ crystal lattice and surface NO_x species allowed the more efficient utilization of visible light. Simultaneously, interstitial [NOB] and N species and surface B₂O₃ and NO_x species facilitated the separation of photo generated electrons and holes and suppress their recombination effectively. Hence, B–N-TiO₂ showed a higher photocatalytic activity than pure TiO₂, N-doped TiO₂ (N-TiO₂) and B-doped TiO₂ (B-TiO₂) under both UV and visible light irradiation.

Keywords: TiO; ₂; B and N codoping; Photocatalytic activity; Interstitial B ions; Interstitial N ions; Surface species

Optical and structural properties of Si-doped ZnO thin films by I. Sorar; D. Saygin-Hinczewski; M. Hinczewski; F.Z. Tepehan (pp. 7343-7349).

► Thin films of Si-doped ZnO were prepared by the sol–gel spin coating method. ► The optical and structural properties of the films were investigated to see the effects of Si dopant concentration for three different heat treatments: 250, 350, and 550°C. ► The optical characteristics for all the films were modeled using a Tauc–Lorentz-based dielectric function and an exponential Urbach tail in the sub-gap regime.Transparent thin films of Si-doped ZnO were prepared by the sol–gel spin coating method. The optical and structural properties of the films were investigated to see the effects of Si dopant concentration for three different heat treatments: 250, 350, and 550°C. Doping is most significant at the highest annealing temperature, where the structure of the films is crystalline at low Si values, and deteriorates as Si levels are increased. Optically, the result is increased transmittance and decreased reflectance with doping for the near-UV and visible ranges. The large changes in the near-UV region (20–50% increase in transmittance relative to pure ZnO) are due to weaker excitonic absorption as crystallinity is destroyed by doping. The films at 250 and 350° C were amorphous, but the 350° C samples showed optical trends qualitatively similar to 550° C (though less pronounced). Band gaps were shifted slightly upwards with doping, though at higher annealing temperatures the values remained within 2% of the 3.3eV pure ZnO result at all Si levels. AFM measurements of RMS surface roughness varied in a small range from ≲ 1 to 7nm, with the roughest samples being pure ZnO at 250°C, and low Si dopings at 550°C. The optical characteristics for all the films, regardless of heat treatment or doping, were successfully modeled using a Tauc–Lorentz-based dielectric function, consisting of two oscillator terms describing near-band-gap absorption, and an exponential Urbach tail in the sub-gap regime.

Keywords: Zinc oxide; Sol–gel; Si-doped ZnO; Optical properties; Structural properties; Tauc–Lorentz dielectric model

Controllable wettability of poly(ethylene terephthlate) film modified by oxygen combined inductively and capacitively coupled radio-frequency plasma by M.K. Lei; Y. Liu; Y.P. Li (pp. 7350-7358).

► Oxygen plasma modification under combined ICP and CCP improves wettability of PET. ► Plasma density and ion-flux energy condition plasma functionalization and etching. ► Plasma functionalization and etching independently determine dynamic contact angles. ► Polar functional group affects contact angles below a threshold of surface roughness. ► Over threshold contact angles depend on polar functional group and surface roughness.Poly(ethylene terephthalate) (PET) film was modified by using oxygen combined inductively coupled radio-frequency plasma (ICP) and capacitively coupled radio-frequency plasma (CCP) at the radio-frequency (RF) power of 200W and 100W, respectively, for a treatment time up to 300s. The RF plasma modification under the combined ICP and CCP mode with the controllable oxygen plasma density and oxygen ion-flux energy significantly improved the wettability of PET film, due to the creation of the polar functional groups containing oxygen, such as C–O and O–CO, and the increase of the surface roughness. At a low surface roughness, the polar functional groups on the PET film affected both the advancing contact angles and receding contact angles. When the surface roughness increased over a threshold, the advancing contact angles mainly depended on the polar functional groups, and the receding contact angles were particularly dependent on the surface roughness. Therefore, the controllable advancing contact angles and receding contact angles on the plasma-modified PET film were independently determined by plasma functionalization and plasma etching under the combined ICP and CCP mode.

Keywords: Radio-frequency plasma modification; Poly(ethylene terephthalate); Oxygen; Wettability; Dynamic contact angle; Inductively coupled plasma; Capacitively coupled plasma

Effects of different carbon precursors on synthesis of multiwall carbon nanotubes: Purification and Functionalization by Yaser Shirazi; Maryam Ahmadzadeh Tofighy; Toraj Mohammadi; Afshin Pak (pp. 7359-7367).

► CNTs was synthesized using cyclohexanol and xylene. ► Cyclohexanol reduces amorphous carbon and catalyst deactivation. ► Cyclohexanol can enhance crystallinity and growth of CNTs. ► HNO₃ 8M treatment removes encapsulated catalyst particles from CNTs. ► Among other acid treatments, HNO₃ 8M prevents CNTs damaging.Cyclohexanol and xylene were used as carbon precursors, for synthesis of multiwall carbon nanotubes (MWCNTs) arrays in a CVD system at temperature of 750°C, using nitrogen as carrier gas and ferrocene as catalyst. Different characterization methods were employed to compare the MWCNTs structure synthesized by these two precursors. All scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA) and Raman spectroscopy results illustrated that using cyclohexanol could significantly reduce formation of amorphous carbon and catalyst particles in the as-grown CNTs. The less amorphous carbon can be attributed to in situ oxidation in presence of oxygen atom of cyclohexanol. Characterizations showed that MWCNTs with high purity could be obtained using cyclohexanol as carbon precursor. The as-grown MWCNTs were purified by oxidation and acid treatment. Characterization of the purified MWCNTs using HNO₃/H₂SO₄ (1/3 or 1/1), 8M HCl or 8M HNO₃ was carried out. The results showed that 8M HNO₃ could be considered as the best chemical to obtain more pure MWCNTs, less amorphous and metal particles and less damaged MWCNTs. The Raman spectroscopy results demonstrated that HNO₃/H₂SO₄ (1/3) treatment could more disorder the MWCNTs structure and this was attributed to the bigger destroying effect of this acid treatment. Furthermore, the TEM analysis of MWCNTs before and after acid treatment revealed that acid treatment could remove encapsulated catalyst particles. The FTIR analysis illustrated that purification of the MWCNTs with nitric acid could connect the functional groups onto the outer surface of MWCNTs and this resulted in more dispersion of the MWCNTs in water.

Keywords: MWCNTs; Carbon precursor; Deactivated catalyst; Purification; Functionalization; Dispersion

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Applied Surface Science (v.257, #16)

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Applied Surface Science (v.257, #16)