Check out our New Publishers' Select for Free Articles

Applied Surface Science (v.257, #3)

Editorial Board (pp. ii).

Superhydrophobic wind turbine blade surfaces obtained by a simple deposition of silica nanoparticles embedded in epoxy by Rachid Karmouch; Guy G. Ross (pp. 665-669).

Samples of wind turbine blade surface have been covered with a superhydrophobic coating made of silica nanoparticles embedded in commercial epoxy paint. The superhydrophobic surfaces have a water contact angle around 152°, a hysteresis less than 2° and a water drop sliding angle around 0.5°. These surfaces are water repellent so that water drops cannot remain motionless on the surface. Examination of coated and uncoated surfaces with scanning electron microscopy and atomic force microscopy, together with measurements of water contact angles, indicates that the air trapped in the cavity enhances the water repellency similarly to the lotus leaf effect. Moreover, this new coating is stable under UVC irradiation and water pouring. The production of this nanoscale coating film being simple and low cost, it can be considered as a suitable candidate for water protection of different outdoor structures.

Keywords: Superhydrophobic; Lotus effect; Contact angle hysteresis; Silica nanoparticles; Icephobic; Epoxy paint

Correlation between microstructure and optical properties of nano-crystalline TiO₂ thin films prepared by sol–gel dip coating by R. Mechiakh; N. Ben Sedrine; R. Chtourou; R. Bensaha (pp. 670-676).

Titanium dioxide thin films have been prepared from tetrabutyl-orthotitanate solution and methanol as a solvent by sol–gel dip coating technique. TiO₂ thin films prepared using a sol–gel process have been analyzed for different annealing temperatures. Structural properties in terms of crystal structure were investigated by Raman spectroscopy. The surface morphology and composition of the films were investigated by atomic force microscopy (AFM). The optical transmittance and reflectance spectra of TiO₂ thin films deposited on silicon substrate were also determined. Spectroscopic ellipsometry study was used to determine the annealing temperature effect on the optical properties and the optical gap of the TiO₂ thin films. The results show that the TiO₂ thin films crystallize in anatase phase between 400 and 800°C, and into the anatase–rutile phase at 1000°C, and further into the rutile phase at 1200°C. We have found that the films consist of titanium dioxide nano-crystals. The AFM surface morphology results indicate that the particle size increases from 5 to 41nm by increasing the annealing temperature. The TiO₂ thin films have high transparency in the visible range. For annealing temperatures between 1000 and 1400°C, the transmittance of the films was reduced significantly in the wavelength range of 300–800nm due to the change of crystallite phase and composition in the films. We have demonstrated as well the decrease of the optical band gap with the increase of the annealing temperature.

Keywords: TiO; ₂; Sol–gel; Thin films; Anatase; Rutile; Annealing

Synthesis and photoluminescence properties of ZnO nanorods and nanotubes by W.J. Liu; X.Q. Meng; Yi Zheng; Wei Xia (pp. 677-679).

Different morphologies of zinc oxide (ZnO) nanorods and nanotubes, which were grown under the same conditions but different dissolving processes, are prepared in our experiment through hydrothermal method. After the growth process, cooling down the reactor naturally or dissolving at a constant temperature of 40°C, preferential dissolution will occur at different places on the tip of ZnO nanorods. During the dissolution process, different dissolution rates on the entire surface of nanorod will lead to different nanostructures. ZnO nanorods and nanotubes on Cu substrates display the same PL property with strong green emission but weak UV emission, while ZnO nanorods on Si substrates exhibits a relatively strong UV emission.

Keywords: Nanorods; Nanotubes; Hydrothermal method; Photoluminescence

Synthesis of 10nm Ag nanoparticle polymer composite pastes for low temperature production of high conductivity films by PingAn Hu; William O’Neil; Qin Hu (pp. 680-685).

The conversion of silver nanoparticle (NP) paste films into highly conductive films at low sintering temperature is an important requirement for the developing areas of additive fabrication and printed electronics. Ag NPs with a diameter of ∼10nm were prepared via an improved chemical process to produce viscous paste with a high wt%. The paste consisted of as-prepared Ag NP and an organic vehicle of ethylcellulose that was deposited on glass and Si substrates using a contact lithographic technique. The morphology and conductivity of the imprinted paste film were measured as a function of sintering temperature, sintering time and the percentage ratio of Ag NP and ethylcellulose. The morphology and conductivity were examined using scanning electron microscopy (SEM) and a two-point probe electrical conductivity measurement. The results show that the imprinted films were efficiently converted into conducting states when exposed to sintering temperature in the range of 200–240°C, this temperature is lower than the previously reported values for Ag paste.

Keywords: Nanoparticle; Conductivity; Film; Printing; Ag

Formation of periodic surface nanostructures on Ti³⁺:Al₂O₃ crystals using femtosecond laser pulses by Nobuhiro Kodama; Koshun Saito; Takayuki Nakaya; Tomoko Takahashi; Daisuke Shibata; Hidetoshi Takeda (pp. 686-690).

Periodic surface nanostructures are observed on Ti³⁺:Al₂O₃ single crystals that have been irradiated by a single focused beam from a femtosecond pulsed laser (wavelength: 800nm; pulse duration: 130 and 152fs). Atomic force microscopy images of single-ablated zones and modified structures created by fixing and translating samples through the focal region of a linearly polarized laser beam reveal self-organized periodic surface nanostructures (ripples) with a subwavelength spacing, which are oriented perpendicular to the electric-field vector of the laser beam. The period of the subwavelength ripples obtained by linearly polarized laser irradiation varies from ∼ λ/5 to 2 λ/5 ( λ: incident laser wavelength) depending on the laser pulse energy. This phenomenon can be explained by assuming that the incident light field interferes with the electric field of electron plasma waves propagating inside the material; this interference periodically modulates the electron plasma density and modifies the surface ablation. In addition, for the first time, we observe screw-shaped nanostructures in the focal spot of circularly polarized beam irradiation. The morphology of these nanostructures appears to reflect the circular polarization of the laser light.

Keywords: Nanostructure; Ablation; Femtosecond laser

Surface hardening of titanium by pulsed Nd:YAG laser irradiation at 1064- and 532-nm wavelengths in nitrogen atmosphere by Naofumi Ohtsu; Misao Yamane; Kenji Kodama; Kazuaki Wagatsuma (pp. 691-695).

The surface hardness of titanium modified by laser irradiation at different wavelengths in nitrogen atmosphere was investigated. Further, surface characteristics such as morphology, chemical state, and chemical composition in the depth direction were also studied. The size and depth of the craters observed in the laser-irradiated spots increased monotonically with an increase in the laser power. Furthermore, the crater formed by the 532-nm laser was deeper than that formed by the 1064-nm laser for the same laser power. Laser power beyond a certain threshold value was required to obtain a titanium nitride layer. When the laser power exceeds the threshold value, a titanium nitride layer of a few tens of nanometers in thickness was formed on the substrate, whereas a titanium oxide layer containing small amounts of nitrogen was formed when the laser power is below the threshold value. Thus, it was shown that laser irradiation using appropriate laser parameters can successfully harden a titanium substrate, and the actual hardness of the titanium nitride layer, measured by nanoindentation, was approximately five times that of an untreated titanium surface.

Keywords: Laser nitridation; Laser wavelength; Depth profile; Nanoindentation

A study of Ta_xC1_−x coatings deposited on biomedical 316L stainless steel by radio-frequency magnetron sputtering by M.H. Ding; B.L. Wang; L. Li; Y.F. Zheng (pp. 696-703).

In this paper, Ta_xC1_−x coatings were deposited on 316L stainless steel (316L SS) by radio-frequency (RF) magnetron sputtering at various substrate temperatures ( T_s) in order to improve its corrosion resistance and hemocompatibility. XRD results indicated that T_s could significantly change the microstructure of Ta_xC1_−x coatings. When T_s was <150°C, the Ta_xC1_−x coatings were in amorphous condition, whereas when T_s was ≥150°C, TaC phase was formed, exhibiting in the form of particulates with the crystallite sizes of about 15–25nm ( T_s=300°C). Atomic force microscope (AFM) results showed that with the increase of T_s, the root-mean-square (RMS) values of the Ta_xC1_−x coatings decreased. The nano-indentation experiments indicated that the Ta_xC1_−x coating deposited at 300°C had a higher hardness and modulus. The scratch test results demonstrated that Ta_xC1_−x coatings deposited above 150°C exhibited good adhesion performance. Tribology tests results demonstrated that Ta_xC1_−x coatings exhibited excellent wear resistance. The results of potentiodynamic polarization showed that the corrosion resistance of the 316L SS was improved significantly because of the deposited Ta_xC1_−x coatings. The platelet adhesion test results indicated that the Ta_xC1_−x coatings deposited at T_s of 150°C and 300°C possessed better hemocompatibility than the coating deposited at T_s of 25°C. Additionally, the hemocompatibility of the Ta_xC1_−x coating on the 316L SS was found to be influenced by its surface roughness, hydrophilicity and the surface energy.

Keywords: Ta; _x; C; 1−; _x; coating; 316L stainless steel; Microstructure; Mechanical property; Corrosion; Hemocompatibility

Characterization of TiO₂/Au/TiO₂ films deposited by magnetron sputtering on polycarbonate substrates by Daeil Kim (pp. 704-707).

Transparent and conducting TiO₂/Au/TiO₂ (TAuT) films were deposited by reactive magnetron sputtering on polycarbonate substrates to investigate the effect of the Au interlayer on the optical, electrical, and structural properties of the films. In TAuT films, the Au interlayer thickness was kept at 5nm. Although total thickness was maintained at 100nm, the stack structure was varied as 50/5/45, 70/5/25, and 90/5/5nm.In XRD pattern, the intermediate Au films were crystallized, while all TAuT films did not show any diffraction peaks for TiO₂ films with regardless of stack structure. The optical and electrical properties were dependent on the stack structure of the films. The lowest sheet resistance of 23Ω/□ and highest optical transmittance of 76% at 550nm were obtained from TiO₂ 90nm/Au 5nm/TiO₂ 5nm films. The work function was dependent on the film stack. The highest work function (4.8eV) was observed with the TiO₂ 90nm/Au 5nm/TiO₂ 5nm film stack. The TAuT film stack of TiO₂ 90nm/Au 5nm/TiO₂ 5nm films is an optimized stack that may be an alternative candidate for transparent electrodes in flat panel displays.

Keywords: TiO; ₂; Au; Sputtering; Work function; Figure of merit

Highly conductive and transparent laser ablated nanostructured Al: ZnO thin films by R. Vinodkumar; I. Navas; S.R. Chalana; K.G. Gopchandran; V. Ganesan; Reji Philip; S.K. Sudheer; V.P. Mahadevan Pillai (pp. 708-716).

Al doped ZnO thin films are prepared by pulsed laser deposition on quartz substrate at substrate temperature 873K under a background oxygen pressure of 0.02mbar. The films are systematically analyzed using X-ray diffraction, atomic force microscopy, micro-Raman spectroscopy, UV–vis spectroscopy, photoluminescence spectroscopy, z-scan and temperature-dependent electrical resistivity measurements in the temperature range 70–300K. XRD patterns show that all the films are well crystallized with hexagonal wurtzite structure with preferred orientation along (002) plane. Particle size calculations based on XRD analysis show that all the films are nanocrystalline in nature with the size of the quantum dots ranging from 8 to 17nm. The presence of high frequency E₂ mode and longitudinal optical A₁ (LO) modes in the Raman spectra suggest a hexagonal wurtzite structure for the films. AFM analysis reveals the agglomerated growth mode in the doped films and it reduces the nucleation barrier of ZnO by Al doping. The 1% Al doped ZnO film presents high transmittance of ∼75% in the visible and near infrared region and low dc electrical resistivity of 5.94×10⁻⁶Ωm. PL spectra show emissions corresponding to the near band edge (NBE) ultra violet emission and deep level emission in the visible region. Nonlinear optical measurements using the z-scan technique shows optical limiting behavior for the 5% Al doped ZnO film.

Keywords: Pulsed laser ablation; Nanostructured zinc oxide films; Aluminum doped ZnO; Transparent conducting oxide; Solar cell materials; Luminescent materials; Optical limiter

Electrodeposition of Ni–Co composites containing nano-CeO₂ and their structure, properties by Meenu Srivastava; V.K. William Grips; K.S. Rajam (pp. 717-722).

One of the most powerful rare earth oxides, ceria CeO₂ was incorporated in Ni matrix and the effect of cobalt addition in the matrix, on the structure and properties has been studied. The amount of cobalt incorporated in the Ni matrix was in the range of 25–85wt.%. The presence of cobalt resulted in a marginal variation in CeO₂ content from 5 to 8wt.%. The microhardness studies revealed that a maximum value of 540Hk_50gf was obtained in the presence of 25wt.% cobalt in Ni–CeO₂ matrix compared to 50 and 85wt.% addition. The presence of 25wt.% cobalt in Ni–CeO₂ matrix also improved its wear resistance as seen from Tribology studies. The wear products were identified using Raman Spectroscopy. The X-ray diffraction (XRD) studies showed that an increase in cobalt content from 25 to 85wt.% resulted in a change in crystal structure from fcc to hcp. A change in surface morphology with variation in cobalt content was seen from scanning electron microscopy (SEM). It was perceived from the thermal stability studies that the presence of 85wt.% cobalt in Ni–CeO₂ matrix imparted better stability in microhardness at temperatures up to 800°C. Although, the incorporation of cobalt in Ni–CeO₂ matrix enhanced the microhardness, wear resistance and thermal stability it did not improve the corrosion resistance as noticed from immersion corrosion studies.

Keywords: Nanocomposite; Ni–CeO; ₂; Ni–Co–CeO; ₂; Tribology studies; Thermal stability; Corrosion resistance

Fragmentation of gold flowers into nanopetals by high energy electron irradiation by Vinayak A. Dhumale; Preeti V. Shah; Vasant N. Bhoraskar; Rishi B. Sharma (pp. 723-726).

Gold nanoflowers were obtained by reducing chloroauric acid with tri-sodium citrate at a temperature of 95°C. The UV–vis spectroscopy and scanning electron microscopy techniques were employed to monitor the growth of gold nanoflowers. The size and shape of the nanocrystallites of gold in the flowers were determined by X-ray diffraction and transmission electron microscopy methods. The 3-dimensional gold nanoflowers got fragmented into 2-dimensional petal-like nanostructures upon irradiation with 6-MeV electrons. The average size of crystallites of gold after electron beam irradiation was found to be ∼10nm.

Keywords: Gold nanoflowers; Gold nanopetals; High energy electrons

CuPd interface charge and energy quantum entrapment: A tight-binding and XPS investigation by Yanguang Nie; Yan Wang; Yi Sun; Ji Sheng Pan; B.R. Mehta; Manika Khanuja; S.M. Shivaprasad; Chang Q. Sun (pp. 727-730).

Materials at heterojunction interfaces demonstrate many physical and chemical properties that are indeed fascinating with mechanisms that need yet to be explored. We show herewith that the “interface charge and energy quantum entrapment due to bond order distortion and bond nature alteration” perturbs essentially the Hamiltonian and hence the binding energy of the CuPd alloy interface. Analyzing the X-ray photoelectron emission of the thermally induced evolution of the Cu 2p and Pd 3d core-level energies at the Cu–Pd interface before and after thermally alloying revealed that the Pd 3d and Cu 2p interfacial potential traps are 0.36 and 0.95 times deeper than the potential wells of the corresponding bulk constituents standing alone.

Keywords: Heterojunctions; Nanofabrications; EXAFS; NEXAFS; SEXAFS; Electronic band structure; Photoelectron spectroscopies

Grafting poly(ethylene glycol) monomethacrylate onto Fe₃O₄ nanoparticles to resist nonspecific protein adsorption by Shaoxiong Qin; Linlin Wang; Xu Zhang; Gaosheng Su (pp. 731-735).

Magnetic nanoparticles grafted with poly(poly(ethylene glycol) monomethacrylate) (P(PEGMA)) were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization. In this approach, S-benzyl S′-trimethoxysilylpropyltrithiocarbonate, used as a chain transfer agent for RAFT, was first immobilized onto the magnetic nanoparticle surface, and then PEGMA was grafted onto the surface of magnetic nanoparticle via RAFT polymerization. The results showed that P(PEGMA) chains grew from magnetic nanoparticles by surface-induced RAFT polymerization. The grafted P(PEGMA) chains can decrease the nonspecific adsorption of proteins on the surface of Fe₃O₄ nanoparticles.

Keywords: Magnetic nanoparticles; Surface modification; Reversible addition-fragmentation chain transfer polymerization; Nonspecific protein adsorption

Effect of corona pre-treatment on the performance of gas barrier layers applied by atomic layer deposition onto polymer-coated paperboard by Terhi Hirvikorpi; Mika Vähä-Nissi; Ali Harlin; Jaana Marles; Ville Miikkulainen; Maarit Karppinen (pp. 736-740).

The effect of corona pre-treatment on the performance of Al₂O₃ and SiO₂ gas barrier layers applied by atomic layer deposition onto polymer-coated paperboards was studied. Both polyethylene and polylactide coated paperboards were corona treated prior to ALD. Corona treatment increased surface energies of the paperboard substrates, and this effect was still observed after several days. Al₂O₃ and SiO₂ films were grown on top of the polymer coatings at temperature of 100°C using the atomic layer deposition (ALD) technique. For SiO₂ depositions a new precursor, bis(diethylamido) silane, was used. The positive effect of the corona pre-treatment on the barrier properties of the polymer-coated paperboards with the ALD-grown layers was more significant with polyethylene coated paperboard and with thin deposited layers (shorter ALD process). SiO₂ performed similarly to Al₂O₃ with the PE coated board when it comes to the oxygen barrier, while the performance of SiO₂ with the biopolymer-coated board was more moderate. The effect of corona pre-treatment was negligible or even negative with the biopolymer-coated board. The ALD film growth and the effect of corona treatment on different substrates require further investigation.

Keywords: Atomic layer deposition; Corona; Barrier; Packaging material; Silicon oxide; Aluminum oxide

Characterization on titanium surfaces and its effect on photocatalytic bactericidal activity by Hyeon-Cheol Joo; Young-Jun Lim; Myung-Joo Kim; Ho-Beom Kwon; Jun-Hyun Han (pp. 741-746).

Many studies have been published on the use of TiO₂ as a photocatalyst, which decomposes various organic compounds under UV illumination by generating various radicals. The purpose of the present study was to evaluate the photocatalytic bactericidal effects of variously treated titanium surfaces on Escherichia coli K-12. The specimens were fabricated from grade 4 commercially pure titanium, 12mm in diameter and 1mm in thickness. Five different surfaces were prepared (MA: machined surface; AO: anodized at 300V; NO: NaOH-treated; NW: NaOH- and water-treated; and HT: heat-treated). Surface analysis was performed using scanning electron microscopy, optical interferometer, and thin-film X-ray diffractometry. Photocatalytic activity of each group was confirmed by degradation of methylene blue (MB). The antibacterial activity was assessed by calculating the survival ratio in a drop of a culture of E. coli placed on the surface under UV illumination. Significant photocatalytic activity and bactericidal effects were observed on the titanium surfaces of AO and NW, regardless of the surface roughness ( P<0.01). The group with anatase was the most susceptible to the photocatalytic effect, while the surface without anatase showed the least susceptibility. Based on this in vitro study, the crystallography of the oxide layer on its titanium surfaces is an important factor affecting the photocatalytic bactericidal activity.

Keywords: Bactericidal effect; Photocatalyst; Titanium dioxide; Anatase; UV illumination

Preparation and characterization of graphene/CdS nanocomposites by Jili Wu; Song Bai; Xiaoping Shen; Lei Jiang (pp. 747-751).

Graphene-based nanocomposites are emerging as a new class of materials that hold promise for many applications. In this paper, we present a facile approach for the preparation of graphene/CdS nanocomposites through simple reflux processes, in which thiourea (CS(NH₂)₂) and thioacetamide (C₂H₅NS) act as a sulphide source, respectively. The samples were characterized by the X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectrum (FT-IR), ultraviolet–visible (UV–vis) spectroscopy and thermogravimetry analysis. It was shown that in the nanocomposites, the CdS nanoparticles were densely and uniformly deposited on the graphene sheets, and the sulphide source used has a great influence on the morphology, structure and property of the graphene/CdS nanocomposites. The good distribution of CdS nanoparticles on graphene sheets guarantees the efficient optoelectronic properties of graphene/CdS and would be promising for practical applications in future nanotechnology.

Keywords: Graphene; Cadmium sulfide; Synthesis; Nanocomposite

Surface modification of indium tin oxide films by amino ion implantation for the attachment of multi-wall carbon nanotubes by Jiao Jiao; Chenyao Liu; Qunxia Chen; Shuoqi Li; Jingbo Hu; Qilong Li (pp. 752-755).

Amino ion implantation was carried out at the energy of 80keV with fluence of 5×10¹⁵ ions cm⁻² for indium tin oxide film (ITO) coated glass, and the existence of amino group on the ITO surface was verified by X-ray photoelectron spectroscopy analysis and Fourier transform infrared spectra. Scanning electron microscopy images show that multi-wall carbon nanotubes (MWCNTs) directly attached to the amino ion implanted ITO (NH₂/ITO) surface homogeneously and stably. The resulting MWCNTs-attached NH₂/ITO (MWCNTs/NH₂/ITO) substrate can be used as electrode material. Cyclic voltammetry results indicate that the MWCNTs/NH₂/ITO electrode shows excellent electrochemical properties and obvious electrocatalytic activity towards uric acid, thus this material is expected to have potential in electrochemical analysis and biosensors.

Keywords: Ion implantation; Indium tin oxide; Multi-wall carbon nanotubes; Uric acid

Preparation of titania hollow spheres by catalyst-free hydrothermal method and their high thermal stabilities by Xuan Feng; Ling Yang; Yingliang Liu (pp. 756-761).

TiO₂ hollow spheres have been prepared by hydrothermal method using carbon spheres as hard templates based on template-directed deposition and calcination in order to remove templates. The morphology and structure of samples were systematically characterized by using various techniques, including XRD, zeta analyzer, SEM, TEM, DRS and FTIR. In this approach, the anatase phase was retained for temperatures up to 900°C. Moreover, negative charged titania is deposited onto the negative charged surface of carbon spheres, which is proved by nanoparticle size analyzer. Therefore, a possible formation mechanism of TiO₂ hollow spheres was proposed. TiO₂ hollow spheres calcined at 550°C exhibited the superior photocatalytic activity for the degradation of Rhodamine B, 2.9 times greater than that of Degussa P25. Furthermore, thermal stability of TiO₂ hollow spheres was examined. Fortunately, we found that hollow structures could still be visible distinctly after calcining at 900°C.

Keywords: TiO; ₂; hollow spheres; Anatase; Thermal stability properties; Electrostatic adsorption; Photocatalytic degradation

Surface fractal analysis of pore structure of high-volume fly-ash cement pastes by Qiang Zeng; Kefei Li; Teddy Fen-Chong; Patrick Dangla (pp. 762-768).

The surface fractal dimensions of high-volume fly-ash cement pastes are evaluated for their hardening processes on the basis of mercury intrusion porosimetry (MIP) data. Two surface fractal models are retained: Neimark's model with cylindrical pore hypothesis and Zhang's model without pore geometry assumption. From both models, the logarithm plots exhibit the scale-dependent fractal properties and three distinct fractal regions (I, II, III) are identified for the pore structures. For regions I and III, corresponding to the large (capillary) and small (C-S-H inter-granular) pore ranges respectively, the pore structure shows strong fractal property and the fractal dimensions are evaluated as 2.592–2.965 by Neimark's model and 2.487–2.695 by Zhang's model. The fractal dimension of region I increases with w/ b ratio and hardening age but decreases with fly-ash content by its physical filling effect; the fractal dimension of region III does not evolve much with these factors. The region II of pore size range, corresponding to small capillary pores, turns out to be a transition region and show no clear fractal properties. The range of this region is much influenced by fly-ash content in the pastes. Finally, the correlation between the obtained fractal dimensions and pore structure evolution is discussed in depth.

Keywords: Fractal dimension; Fly-ash; Mercury intrusion porosimetry; Pore structure

Adsorption of hexavalent chromium onto montmorillonite modified with hydroxyaluminum and cetyltrimethylammonium bromide by Bingjie Hu; Hanjin Luo (pp. 769-775).

Aluminum hydroxypolycation and cetyltrimethylammonium bromide (CTMAB) were chosen to synthesize inorganic–organic pillared montmorillonite. Three different methods were employed for the intercalation. The characteristics of natural and modified montmorillonite were determined with X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), X-ray photoelectron spectrum (XPS), and zeta potential. It was found that aluminum hydroxypolycation and CTMAB had either entered the interlayer or sorbed on the external surface of the clay. Different intercalation orders can result in different structures. Batch adsorption of hexavalent chromium (Cr⁶⁺) onto modified montmorillonite was also investigated. The experimental data revealed that if aluminum hydroxypolycation was intercalated before CTMAB, the adsorption capacity was better than that of intercalated simultaneously or CTMAB pre-intercalated. The pH of the solution and environmental temperature had significant influences on the adsorption of Cr⁶⁺. The optimal pH for the removal was about 4, and the temperature of 298K was best suitable. All adsorption processes were rapid during the first 5min and reached equilibrium in 20min. The adsorption kinetics can be described quite well by pseudo-second-order model. The adsorption rates of ACM, CAM and ACCOM were 3.814, 0.915, and 3.143mg/g/min, respectively. The adsorption capacities of Cr⁶⁺ at 298K on ACM, CAM, and ACCOM inferred from the Langmuir model were 11.970, 6.541, and 9.090mg/g, respectively. The adsorption of Cr⁶⁺ on modified montmorillonite was mainly induced by the surface charge and the complexation reaction between CTMA⁺ and hexavalent chromium species at the edge of the clay particle.

Keywords: Modified montmorillonite; Adsorption; Hexavalent chromium; Intercalation order

Laser direct patterning of the T-shaped ITO electrode for high-efficiency alternative current plasma display panels by Zhao-Hui Li; Eou Sik Cho; Sang Jik Kwon (pp. 776-780).

The laser direct patterning technique is one of the new methods of direct etching process to replace the conventional photolithography. In this experiment, a Q-switched diode-pumped Nd:YVO₄ ( λ=1064nm) laser was used to produce the indium–tin oxide (ITO) patterns with a complex T-shaped structure on glass substrate. The results showed that the overlapping rate of laser beam had a major effect on the quality of the edge of the ITO electrode. When the overlapping rate was about 75%, it was possible to obtain optimum linearity in the edge of patterned ITO electrode. By using the optimum conditions of 75% overlapping rate, 500mm/s scanning speed, and 40kHz repetition rate, an alternative current plasma display panels (AC PDPs) with T-shaped ITO electrode was fabricated and characterized. The discharging results showed that the AC PDPs with the laser ablated T-shaped ITO electrode had a better discharging characteristics compared to the conventional sample with wet-etched stripe-type ITO electrode.

Keywords: Laser direct patterning; Overlapping rate; T-shaped ITO electrode; Plasma display panel (PDP)

Simple routes to synthesis and characterization of nanosized tin telluride compounds by Masoud Salavati-Niasari; Mehdi Bazarganipour; Fatemeh Davar; Alireza Amini Fazl (pp. 781-785).

Nanosized tin telluride compounds were prepared by chemical reduction process and hydrothermal methods. The nanosized SnTe compounds were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SnTe nanoalloy prepared by chemical reduction process presented quasi-spherical morphology with aggregation. The sizes of particle were 40–50nm. The powder prepared by hydrothermal process was nearly nanospheres, and the particle sizes were 30–40nm with narrow distribution. The effect of capping agent, reductant sort, and reaction temperature on the morphology, the particle sizes and the phase of SnTe alloys have been investigated. Experimental results indicated that N₂H₄·H₂O plays a crucial role in the formation of nanosized rode-like SnTe compounds.

Keywords: SnTe; Nanosized; Hydrothermal; Chemical reduction

X-ray photoelectron spectroscopy study of the passive films formed on thermally sprayed and wrought Inconel 625 by M.S. Bakare; K.T. Voisey; M.J. Roe; D.G. McCartney (pp. 786-794).

There is a well known performance gap in corrosion resistance between thermally sprayed corrosion resistant coatings and the equivalent bulk materials. Interconnected porosity has an important and well known effect, however there are additional relevant microstructural effects. Previous work has shown that a compositional difference exists between the regions of resolidified and non-melted material that exist in the as-sprayed coatings. The resolidified regions are depleted in oxide forming elements due to formation of oxides during coating deposition. Formation of galvanic cells between these different regions is believed to decrease the corrosion resistance of the coating. In order to increase understanding of the details of this effect, this work uses X-ray photoelectron spectroscopy (XPS) to study the passive films formed on thermally sprayed coatings (HVOF) and bulk Inconel 625, a commercially available corrosion resistant Ni–Cr–Mo–Nb alloy. Passive films produced by potentiodynamic scanning to 400mV in 0.5M sulphuric acid were compared with air-formed films. The poorer corrosion performance of the thermally sprayed coatings was attributed to Ni(OH)₂, which forms a loose, non-adherent and therefore non-protective film. The good corrosion resistance of wrought Inconel 625 is due to formation of Cr, Mo and Nb oxides.

Keywords: Inconel 625 alloy; HVOF thermally sprayed coating; X-ray photoelectron spectroscopy; Binding energy; Passive films

Enhanced photoactivity of CuPp-TiO₂ photocatalysts under visible light irradiation by Xiang-fei Lü; Jun Li; Chen Wang; Ming-yue Duan; Yun Luo; Gui-ping Yao; Jun-Long Wang (pp. 795-801).

Three novel porphyrins, 5,10,15-tri-phenyl-20-[4-(3-phenoxy)-propoxy]phenyl porphyrin, 5,15-di-phenyl-10,20-di-[4-(3-phenoxy)-propoxy]phenyl porphyrin and 5-phenyl-10,15,20-tri- [4-(3-phenoxy)-propoxy]phenyl porphyrin, and their corresponding copper(II) complexes were synthesized and characterized spectroscopically. The photocatalytic effects of TiO₂ samples impregnated with copper(II) porphyrins was investigated by photodegradation of 4-nitrophenol (4-NP) in aqueous solution under visible light. The photocatalysts were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–vis spectra and FT-IR spectra. The results indicated that CuPps were successfully loaded and interacted with the surface of TiO₂ microsphere, which is crucial to enhance the activity of the catalytic composite under visible light.

Keywords: Copper porphyrins; TiO; ₂; Photocatalysis; Degradation

A fluorescent probe for zinc detection based on organically functionalized SBA-15 by Zhengping Dong; Zihao Dong; Pan Wang; Xin Tian; Huamei Geng; Rong Li; Jiantai Ma (pp. 802-806).

In this study, highly ordered mesoporous silica material (SBA-15) functionalized with N-(quinoline-8-yl)-2-(3-triethoxysilyl-propylamino)-acetamide (QTPA) as zinc probe has been reported. The anchoring to the surface of the SBA-15 was carried out by the reaction between the precursor and the hydroxyl groups available on the inner surface of the support. The primary ordered mesoporous structure of SBA-15 was well preserved after the grafting procedure. Fluorescence characterization showed that the obtained organic–inorganic hybrid composite displayed highly selective and sensitive to Zn²⁺ ion over other cations such as Cd²⁺, Pb²⁺, Ni²⁺ and Co²⁺. And the hybrid material has ideal chemical and spectroscopic properties for further biological and environmental applications.

Keywords: Fluorescent probe; SBA-15; Zinc detection; Functionalization

First-principles study on the structural and electronic properties of graphene upon benzene and naphthalene adsorption by A.Z. AlZahrani (pp. 807-810).

Within the framework of the local density approximation (LDA) of the density functional theory (DFT) and the pseudopotential method, we have carried out ab initio calculations to investigate the structural and electronic properties of graphene upon the adsorption of benzene and naphthalene molecules. Our total-energy calculations suggest that, for both benzene and naphthalene adsorbed on graphene, the stack configuration is the most stable structure. The corresponding adsorption energies at different sites are estimated for both molecular adsorbates. The equilibrium parameters and the electronic band structure for the stable geometries have been calculated and compared with the available findings.

Keywords: Graphene; Density functional calculations; Molecular adsorption; Electronic structure; Dirac Point

Silica–tin nanotubes prepared from rice husk ash by sol–gel method: Characterization and its photocatalytic activity by Farook Adam; Jimmy Nelson Appaturi; Radhika Thankappan; Mohd Asri Mohd Nawi (pp. 811-816).

Silica–tin material has been synthesized by simple sol–gel method using rice husk ash as the source of silica and cetyltrimethylammonium bromide as the surfactant at room temperature. Calcination of the material at 500°C for 5h gave nanotubes with external diameter of 2–4nm and an internal diameter of 1–2nm. The BET specific surface area was found to be 607m²g⁻¹. Nitrogen sorption analysis exhibits a type IV isotherm with H3 hysteresis loop. The powder X-ray diffraction pattern showed that the material is amorphous. The photocatalytic activity of the prepared material was studied towards degradation of methylene blue under UV-irradiation. According to the experimental results the silica–tin nanotubes exhibit high photocatalytic activity compared to pure rice husk silica.

Keywords: Silica–tin nanotubes; Rice husk silica; Sol–gel; Photocatalysis; Methylene blue

The optoelectronic properties of silicon films deposited by inductively coupled plasma CVD by Yanli Qin; Hengqing Yan; Fei Li; Li Qiao; Qiming Liu; Deyan He (pp. 817-822).

Hydrogenated amorphous and microcrystalline silicon films were deposited by inductively coupled plasma chemical vapor deposition (ICP-CVD) at low substrate temperatures using H₂-diluted SiH₄ as a source gas. High-density plasma generated by inductively coupled excitation facilitates the crystallization of silicon films at low temperatures, and microcrystalline silicon films were obtained at the substrate temperature as low as 180°C. The columnar structure of the films becomes more and more compact with an increase of their crystallinity. The reduction of hydrogen content in the films causes a narrowing of the optical bandgap and an enhancement of the absorption with increasing the substrate temperature. The microcrystalline silicon films show two electronic transport mechanisms: one is related to the density of state distribution in the temperature region near room temperature and the other is the variable range hopping between localized electronic states close to the Fermi level below 170K. A reasonable explanation is presented for the dependence of the optoelectronic properties on the microstructure of the silicon films. The films prepared at a substrate temperature of 300°C have highly crystalline and compact columnar structure, high optical absorption coefficient and electrical conductivity, and a low hydrogen content of 3.8%.

Keywords: Silicon films; Substrate temperature; Inductively coupled plasma; Optoelectronic properties

Fabrication of superhydrophobic polyurethane/organoclay nano-structured composites from cyclomethicone-in-water emulsions by I.S. Bayer; A. Steele; P.J. Martorana; E. Loth (pp. 823-826).

Nano-structured polyurethane/organoclay composite films were fabricated by dispersing moisture-curable polyurethanes and fatty amine/amino-silane surface modified montmorillonite clay (organoclay) in cyclomethicone-in-water emulsions. Cyclomethicone Pickering emulsions were made by emulsifying decamethylcyclopentasiloxane (D₅), dodecamethylcyclohexasiloxane (D₆) and aminofunctional siloxane polymers with water using montmorillonite particles as emulsion stabilizers. Polyurethane and organoclay dispersed emulsions were spray coated on aluminum surfaces. Upon thermosetting, water repellent self-cleaning coatings were obtained with measured static water contact angles exceeding 155° and low contact angle hysteresis (<8°). Electron microscopy images of the coating surfaces revealed formation of self-similar hierarchical micro- and nano-scale surface structures. The surface morphology and the coating adhesion strength to aluminum substrates were found to be sensitive to the relative amounts of dispersed polyurethane and organoclay in the emulsions. The degree of superhydrophobicity was analyzed using static water contact angles as well as contact angle hysteresis measurements. Due to biocompatibility of cyclomethicones and polyurethane, developed coatings can be considered for specific bio-medical applications.

Keywords: Nanocomposites; Polyurethane; Cyclomethicone; Emulsion; Superhydrophobic; Clay

Morphology, luminescence, and electrical resistance response to H₂ and CO gas exposure of porous InP membranes prepared by electrochemistry in a neutral electrolyte by O. Volciuc; E. Monaico; M. Enachi; V.V. Ursaki; D. Pavlidis; V. Popa; I.M. Tiginyanu (pp. 827-831).

Porous InP membranes have been prepared by anodization of InP wafers with electron concentration of 1×10¹⁷cm⁻³ and 1×10¹⁸cm⁻³ in a neutral NaCl electrolyte. The internal surfaces of pores in some membranes were modified by electrochemical deposition of gold in a pulsed voltage regime. Photoluminescence and photosensitivity measurements indicate efficient light trapping and porous surface passivation. The photoluminescence and electrical resistivity of the membranes are sensitive to the adsorption of H₂ and CO gas molecules. These properties are also influenced by the deposition of Au nanoparticles inside the pores.

Keywords: Porous InP; Au nanoparticles; Anodization; Electroplating; Photoluminescence; Gas adsorption

Photoemission study of fluorination atmospheric pressure plasma processes on EPDM: Influence of the carrier and fluorinating gas by L. Martínez; Y. Huttel; B. Verheyde; A. Vanhulsel; E. Román (pp. 832-836).

Fluorination plasma treatments at atmospheric pressure were used to modify the surface composition of EPDM elastomer. In this study, two different precursors (CF₄ and SF₆) and two carrier gases (He and Ar) were used for the surface modification of EPDM elastomer. The surface modifications were studied by means of X-ray photoelectron spectroscopy. We have observed a strong influence of the gas selection on the extent of the surface modification induced with these treatments. In general terms, the use of CF₄ generates a higher concentration of fluorine in the elastomer surface. On the other hand, the use of He as carrier gas also increases the effectiveness of the modification process. The fluorine uptake varies between 2 and 13%, although the formation of fluorine-containing functional groups was detected when the amount of fluorine on the surface exceeded 7%. After all treatments, an important oxygen uptake was observed, with amounts three or four times higher than the untreated elastomer.

Keywords: Fluorination; Atmospheric plasma; XPS; Elastomer

Formation and disruption of current paths of anodic porous alumina films by conducting atomic force microscopy by K. Oyoshi; S. Nigo; J. Inoue; O. Sakai; H. Kitazawa; G. Kido (pp. 837-841).

Anodic porous alumina (APA) films have a honeycomb cell structure of pores and a voltage-induced bi-stable switching effect. We have applied conducting atomic force microscopy (CAFM) as a method to form and to disrupt current paths in the APA films. A bi-polar switching operation was confirmed. We have firstly observed terminals of current paths as spots or areas typically on the center of the triangle formed by three pores. In addition, though a part of the current path showed repetitive switching, most of them were not observed again at the same position after one cycle of switching operations in the present experiments. This suggests that a part of alumina structure and/or composition along the current paths is modified during the switching operations.

Keywords: Anodic porous alumina; Scanning probe microscope; Conducting atomic force microscope; Resistive RAM; Current path

Microwave absorption properties of a wave-absorbing coating employing carbonyl-iron powder and carbon black by Lidong Liu; Yuping Duan; Lixin Ma; Shunhua Liu; Zhen Yu (pp. 842-846).

To prevent serious electromagnetic interference, a single-layer wave-absorbing coating employing complex absorbents composed of carbonyl-iron powder (CIP) and carbon black (CB) with epoxy resin as matrix was prepared. The morphologies of CIP and CB were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. The electromagnetic parameters of CIP and CB were measured in the frequency range of 2–18GHz by transmission/reflection technology, and the electromagnetic loss mechanisms of the two particles were discussed, respectively. The microwave absorption properties of the coatings were investigated by measuring reflection loss (RL) using arch method. The effects of CIP ratio, CB content and thickness on the microwave absorption properties were discussed, respectively. The results showed that the higher thickness, CIP or CB content could make the absorption band shift towards the lower frequency range. Significantly, the wave-absorbing coating could be applied in different frequency ranges according to actual demand by controlling the content of CIP or CB in composites.

Keywords: Coating; Carbonyl-iron powder; Carbon black; Electromagnetic parameter; Microwave absorption

Mechanical and tribological properties of Ni/Al multilayers—A molecular dynamics study by Yongzhi Cao; Junjie Zhang; Yingchun Liang; Fuli Yu; Tao Sun (pp. 847-851).

Mechanical and tribological properties of multilayers with nanometer thickness are strongly affected by interfaces formed due to mismatch of lattice parameters. In this study, molecular dynamics (MD) simulations of nanoindentation and following nanoscratching processes are performed to investigate the mechanical and tribological properties of Ni/Al multilayers with semi-coherent interface. The results show that the indentation hardness of Ni/Al multilayers is larger than pure Ni thin film, and the significant strength of Ni/Al multilayers is caused by the semi-coherent interface which acts as a barrier to glide of dislocations during nanoindentation process. The confinement of plastic deformation by the interface during nanoscratching on Ni/Al multilayers leads to smaller friction coefficient than pure Ni thin film. Dislocation evolution, interaction between gliding dislocations and interface, variations of indentation hardness and friction coefficient are studied.

Keywords: Multilayer; Semi-coherent interface; Mechanical and tribological properties; Molecular dynamics

Protective performances of two anti-graffiti treatments towards sulfite and sulfate formation in SO₂ polluted model environment by Paula María Carmona-Quiroga; Itai Panas; Jan-Erik Svensson; Lars-Gunnar Johansson; María Teresa Blanco-Varela; Sagrario Martínez-Ramírez (pp. 852-856).

Specific strategies for protection are being developed to counter both the staining and corrosive effects of polluted air in cities, as well as to allow for efficient removal of unwanted graffiti paintings. These protection strategies employ molecules with tailored functionalities, e.g. being hydrophobic, while maintaining porosity for molecular water vapour permeation.The present study employs SO₂ and water to probe the behaviors of two anti-graffiti treatments, a water-base fluoroalkylsiloxane (“Protectosil Antigraffiti” marketed by Degussa) and an organically modified silicate (Ormosil) synthesized from a polymer chain (polydimethyl siloxane, PDMS) and two network forming alkoxides (Zr propoxide and methyl triethoxy silane, MTES) dissolved in n-propanol, on five building materials, comprising limestone, aged lime mortar, hydrated cement mortar, granite, and brick material.The materials were exposed to a synthetic atmosphere for 20h in a climate chamber, 0.78±0.03ppm of SO₂ and 95% RH. Diffuse reflectance Fourier transform infrared (DR-FTIR) spectra were registered before and after exposure in the climate chamber in the cases of both treated and untreated samples. DR-FTIR, scanning electron microscope (SEM) images and energy dispersive X-ray (EDX) analyses, suggest the anti-graffiti Ormosil to suppress formation of calcium sulfite hemihydrate (the primary initial product of the reaction of calcium compounds with SO₂ and water) on carbonate materials (limestone and lime mortar).In case of the granite, brick and cement mortar, Ormosil has a negligible influence on the SO₂ capture. While no sulfite formation was detected by DR-FTIR, gypsum is inferred to form due to metal oxides and minority compounds catalysed oxidation of sulfite to sulfate. In case of brick, this understanding finds support from SEM images as well as EDX. A priori presence of gypsum in hydrated cement mortars prevents positive identification by SEM. However, support for sulfur accumulation in hydrated cement mortar is provided by means of EDX.In case of a second anti-graffiti considered, Protectosil, no influence of the anti-graffiti treatment on the SO₂ uptake of any of the building materials was observed.

Keywords: Anti-graffiti; Building materials; SO; ₂; DR-FTIR; SEM-EDX

Regeneration of surface roughness by the Langevin equation using stochastic analysis on AFM image of a carbon fiber by Masoud Allahkarami; Jay C. Hanan; Hrishikesh A. Bale (pp. 857-860).

A new method was developed using AFM images of a fiber surface to regenerate the surface roughness in 3D geometry, such as the cylindrical shape of a “model” fiber. The Langevin equation was used to derive the fluctuations of a carbon fiber surface image. The equation contains two quantities, D⁽¹⁾ ( h) and D⁽²⁾ ( h) which in physics represent drift and diffusion coefficients. Knowing this coefficient and adding a proper noise function, a similar surface of larger dimension with the same statistical properties of the initial data was created. The generated surface was mapped into cylindrical coordinates, then a mesh generated. The resulting reconstructed surface, input over the geometry of a cylindrical shape, can be implemented for finite element analysis of a single fiber surrounded by matrix and generalized to a many fiber model.

Keywords: AFM (atomic force microscopy); Stochastic analysis; Surface roughness regeneration; Carbon fiber

Chemical modification of glass surface with a monolayer of nonchromophoric and chromophoric methacrylate terpolymer by Ryszard Janik; Stanisław Kucharski; Anna Sobolewska; Regis Barille (pp. 861-866).

The methacrylate terpolymers, a nonchromophoric and chromophoric one, containing 2-hydroxyethyl groups were reacted with 3-isocyanatopropyltriethoxysilane to obtain reactive polymers able to form covalent bonding with –SiOH groups of the glass surface via triethoxysilane group condensation. Chemical modification of the Corning 2949 glass plates treated in this way resulted in increase of wetting angle from 11° to ca. 70–73°. Determination of ellipsometric parameters revealed low value of the substrate refractive index as compared with that of bulk Corning 2949 glass suggesting roughness of the surface. The AFM image of the bare glass surface and that modified with terpolymer monolayer confirmed this phenomenon. Modification of the glass with the terpolymer monolayer made it possible to create the substrate surface well suited for deposition of familiar chromophore film by spin-coating. The chromophore polymer film deposited onto the modified glass surface was found to be resistant to come unstuck in aqueous solution.

Keywords: Chromophoric methacrylate terpolymer; Glass surface modification; Ellipsometry; AFM

Structural, photochemical and photocatalytic properties of zirconium oxide doped TiO₂ nanocrystallites by Dongfang Zhang; Fanbin Zeng (pp. 867-871).

Composite photocatalysts composed of TiO₂ and ZrO₂ have been prepared via the sol–gel method. The as-prepared nanocomposites are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis spectrometry and fluorescence emission spectra. The results shows that TiO₂/ZrO₂ nanocomposites are composed of mainly anatase titania and tetragonal ZrO₂. Incorporating TiO₂ particles with ZrO₂ plays an important role in promoting the formation of nanoparticles with an anatase structure and leads to decreased fluorescence emission intensity. Most of the TiO₂/ZrO₂ nanocomposites exhibited comparable photocatalytic activity compared with commercial TiO₂ for the degradation aqueous methyl orange (MO) under ultraviolet irradiation, while the composite with Zr/Ti mass ratio of 15.2% shows the highest photocatalytic performances. Furthermore, the as-prepared nanocomposites can be reused with little photocatalytic activity loss. Without any further treatment besides rinsing, the photocatalytic activity of TiO₂/ZrO₂ (15.2%) composites is still higher than after five-cycle utilization.

Keywords: TiO; ₂; /ZrO; ₂; composite; Degradation; Photocatalytic activity

Studies on the interactions of fluorescent-magnetic nanocomposites with biomolecules and cells labeling by Qisui Wang; Tingting Fang; Peng Liu; Xinmin Min; Xi Li (pp. 872-877).

In this study, the fluorescent-magnetic nanocomposites were synthesized. The interactions between nanocomposites and bovine serum albumin (BSA) were studied by absorption and FL titration experiments. The experiments show that binding of nanocomposites and BSA may be caused by the formation of QDs–BSA complex. A magnetic separation method was designed to directly demonstrate the interactions between the surface of bifunctional nanocomposites with CdSe/CdS quantum dots (QDs) and biomolecules (BSA and DNA). The fluorescence (FL) labeling on the Escherchia coli ( E. coli) cells was also successfully developed for studying the biolabeling of the bifunctional nanocomposites. The results directly reveal that the bifunctional nanocomposites can separate biomolecules and label cells. The studies we have performed showed that the fluorescent-magnetic nanocomposites are proved to be a kind of novel biofuctional materials, which can be used in bioseparation and biolabeling applications.

Keywords: Fluorescent-magnetic; Nanocomposites; Magnetic separation; Biomolecules; Cells labeling

Quantitative analysis of graded Cu(In1−_x,Ga_x)Se₂ thin films by AES, ICP-OES, and EPMA by Craig L. Perkins; Brian Egaas; Ingrid Repins; Bobby To (pp. 878-886).

The overall composition and the compositional profile of the quaternary semiconductor Cu(In1−_x,Ga_x)Se₂ (CIGS) have strong effects on the performance of photovoltaic devices based on it. Recent work that has yielded ∼20% efficient solar cells based on CIGS has forced extra attention on quantitative analysis of the absorber layers. In this paper we present details of the procedures used to generate detailed compositional profiles of graded Cu(In1−_x,Ga_x)Se₂ thin films by Auger electron spectroscopy (AES) that when integrated, agree quantitatively with inductively-coupled plasma optical emission spectrometry (ICP-OES) data on the same films. The effects of sample rotation during sputter depth profiling on the quantification results are described. Details of the procedures used for the ICP-OES and wavelength-dispersed electron probe microanalysis (EPMA) analyses are also presented. Finally, we show why X-ray microanalysis techniques alone should not be used to argue that specific windows of copper and gallium concentrations can yield high performance devices.

Keywords: CIGS; Auger; Electron probe microanalysis; Photovoltaics; Solar

Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Sc, Ti, V, Cu and Zn by Mark C. Biesinger; Leo W.M. Lau; Andrea R. Gerson; Roger St.C. Smart (pp. 887-898).

Chemical state X-ray photoelectron spectroscopic analysis of first row transition metals and their oxides and hydroxides is challenging due to the complexity of the 2p spectra resulting from peak asymmetries, complex multiplet splitting, shake-up and plasmon loss structure, and uncertain, overlapping binding energies. A review of current literature shows that all values necessary for reproducible, quantitative chemical state analysis are usually not provided. This paper reports a more consistent, practical and effective approach to curve-fitting the various chemical states in a variety of Sc, Ti, V, Cu and Zn metals, oxides and hydroxides. The curve-fitting procedures proposed are based on a combination of (1) standard spectra from quality reference samples, (2) a survey of appropriate literature databases and/or a compilation of the literature references, and (3) specific literature references where fitting procedures are available. Binding energies, full-width at half maximum (FWHM) values, spin-orbit splitting values, asymmetric peak-shape fitting parameters, and, for Cu and Zn, Auger parameters values are presented. The quantification procedure for Cu species details the use of the shake-up satellites for Cu(II)-containing compounds and the exact binding energies of the Cu(0) and Cu(I) peaks. The use of the modified Auger parameter for Cu and Zn species allows for corroborating evidence when there is uncertainty in the binding energy assignment. These procedures can remove uncertainties in analysis of surface states in nano-particles, corrosion, catalysis and surface-engineered materials.

Keywords: XPS; Peak fitting; Transition metals; Oxides

Investigating the interfacial interaction of different aminosilane treated nano silicas with a polyurethane coating by M. Rostami; Z. Ranjbar; M. Mohseni (pp. 899-904).

In this work different nano silica particles varying in aminosilane functionalities were dispersed into a polyurethane clear coating (PU). The optical clarity of the resulting films as well as the mechanical integrities were studied utilizing haze transmission and dynamic mechanical analysis respectively. In addition, the curing behavior of films was investigated using differential scanning calorimetry. It was found that particle dispersibility directly depended on the amount of grafted silane at the surface of nano silicas. Also the presence of amine functional groups on silica particles resulted in a systematic improvement of Tg and therefore in enhanced mechanical performance. These were attributed to an increased interfacial interaction and formation of some urea linkages in the hard segment of the polyurethane matrix. The DSC analyses also showed that the heat of reaction of particle loaded samples were all lower than that of the blank PU due to the facilitated interaction of amino groups at the silica surface with isocyanate cross-linker.

Keywords: Interfacial interaction; Silica treatment; Amino silane; Polyurethane

Dry etching characteristics of GaN using Cl₂/BCl₃ inductively coupled plasmas by Shengjun Zhou; Bin Cao; Sheng Liu (pp. 905-910).

ICP power/RF power, operating pressure, and Cl₂/BCl₃ gas mixing ratio are altered to investigate the effect of input process parameters on the etch characteristics of GaN films. The etch selectivity of GaN over SiO₂ and photoresist is studied. Although higher ICP/RF power can obtain higher GaN/photoresist etch selectivity, it can result in faceting of sidewall and weird sidewall profile due to photoresist mask erosion. Etch rates of GaN and SiO₂ decrease with the increase of operating pressure, and etch selectivity of GaN over SiO₂ increases with the increasing operating pressure at fixed ICP/RF power and mixture component. The highest etch selectivity of GaN over SiO₂ is 7.92, and an almost vertical etch profile having an etch rate of GaN close to 845.3nm/min can be achieved. The surface morphology and root-mean-square roughness of the etched GaN under different etching conditions are evaluated by atomic force microscopy. The plasma-induced damage of GaN is analyzed using photoluminescence (PL) measurements. The optimized etching process, used for mesa formation during the LED fabrication, is presented. The periodic pattern can be transferred into GaN using a combination of Cl₂/BCl₃ plasma chemistry and hard mask SiO₂. Patterning of the sapphire substrate for fabricating LED with improved extraction efficiency is also possible using the same plasma chemistry.

Keywords: ICP etching; Etching selectivity; SiO; ₂; mask; Photoluminescence measurement

Effect of annealing on the nanoscratch behavior of multilayer Si_0.8Ge_0.2/Si films by Derming Lian (pp. 911-916).

In this study, we examined the nanoscratch behavior of annealed multilayered silicon–germanium (SiGe) films comprising alternating sublayers (Si) deposited using an ultrahigh-vacuum chemical vapor deposition (UHV/CVD) system. Annealing consisted of ex situ thermal treatment in a furnace system. We used a nanoscratch technique to investigate the nanotribological behavior of the SiGe films and atomic force microscopy (AFM) to observe deformation phenomena. Our AFM morphological studies of the SiGe films revealed that pile-up phenomena occurred on both sides of each scratch. The scratched surfaces of the SiGe films that had been subjected to various annealing conditions exhibited significantly different features, it is conjectured that cracking dominates in the case of SiGe films while ploughing dominates during the scratching process. We obtained higher coefficients of friction ( μ) when the ramped force was set at 6000μN, rather than 2000μN, suggesting that annealing of SiGe films leads to higher shear resistance; annealing treatment not only produced misfit dislocations in the form of a significantly wavy sliding surface but also promoted scratching resistance.

Keywords: Silicon–germanium; Ultrahigh-vacuum chemical vapor deposition; Atomic force microscopy; Hardness

Theoretical analysis of fluorine-passivated germanium surface for high- k/Ge gate stack by molecular orbital method by DongHun Lee; Hyun Lee; Takeshi Kanashima; Masanori Okuyama (pp. 917-920).

Energy state and coordination of fluorine (F)-passivated Ge surface have been theoretically analyzed by semi-empirical molecular orbital method in comparison with hydrogen-passivated Ge surface to predict usefulness of F for passivation element and surface stabilization. Heat of formation for the reaction of F atoms and Ge layer system decreased simultaneously without energy barrier. Resultantly, F–Ge bonds were formed on Ge layer system and Ge surface dangling bonds were passivated by F dissimilar to the reaction of H atoms and Ge layer system. Furthermore, it was confirmed experimentally that the electrical properties of HfO₂/Ge gate stack were improved by F₂-ambient treatment of Ge substrate prior to HfO₂ deposition. It is concluded that F-passivation of Ge surface is useful in making stable and low-defective Ge substrate for high- k dielectric layer deposition.

Keywords: Semi-empirical; molecular orbital method; MOPAC; Fluorine; Surface passivation; High-; k; /Ge gate stack

Fast response ultraviolet photoconductive detectors based on Ga-doped ZnO films grown by radio-frequency magnetron sputtering by Jian Sun; Feng-Juan Liu; Hai-Qin Huang; Jian-Wei Zhao; Zuo-Fu Hu; Xi-Qing Zhang; Yong-Sheng Wang (pp. 921-924).

A metal–semiconductor–metal photoconductive detector was fabricated on c-axis preferred oriented Ga-doped ZnO (ZnO:Ga) thin film prepared on quartz by radio-frequency magnetron sputtering. With a 10V bias, a responsivity of about 2.6A/W at 370nm was obtained in the ultraviolet region. The photocurrent increases linearly with incident power density for more than two orders of magnitude. The transient response measurement revealed photoresponse with a rise time of 10ns and a fall time of 960ns, respectively. The results are much faster than those reported in photoconductive detectors based on unintentionally doped n-type ZnO films.

Keywords: Ultraviolet photodetector; ZnO:Ga; Photoconductive detector; ZnO

In vitro biocompatibility of magnesium-incorporated submicro-porous titanium oxide surface produced by hydrothermal treatment by Jin-Woo Park; Youn-Jeong Kim; Je-Hee Jang; Chang-Hyeon An (pp. 925-931).

This study investigated the surface characteristics and in vitro biocompatibility of titanium (Ti) oxide surface incorporating magnesium ions (Mg), produced by hydrothermal treatment using an alkaline Mg-containing solution, for future biomedical applications. The surface characteristics were evaluated by scanning electron microscopy, thin-film X-ray diffractometry, X-ray photoelectron spectroscopy, inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and optical profilometry. Mouse calvaria-derived osteoblastic cell (MC3T3-E1) attachment, spreading, proliferation, alkaline phosphatase (ALP) activity, and osteoblastic gene expression on Mg-containing surfaces were compared with untreated Ti surfaces. Hydrothermal treatment resulted in Mg-incorporated Ti oxide layer with submicro-porous surface structures approximately 2μm in thickness. ICP-AES analysis revealed Mg ions release from treated surfaces into the solution. The Mg-incorporated surface displayed significantly increased cellular attachment and ALP activity compared with untreated surface ( p<0.05), and supported better cell spreading. Real-time polymerase chain reaction analysis showed notably higher mRNA expression of the osteoblast transcription factor genes (Dlx5, Runx2) and the osteoblast phenotype genes (ALP, bone sialoprotein and osteocalcin) in cells grown on the Mg-incorporated surfaces than untreated surfaces. These results demonstrate that the Mg-incorporated submicro-porous Ti oxide surface produced by hydrothermal treatment may improve implant osseointegration by enhancing the attachment, spreading and differentiation of osteoblastic cells.

Keywords: Titanium oxide; Osteoblast; Surface chemistry; Surface micro-topography; Hydrothermal treatment

Effect of sulfur on the growth of carbon nanotubes by detonation-assisted chemical vapor deposition by Can Wang; Liang Zhan; Yan-li Wang; Wen-Ming Qiao; Xiaoyi Liang; Li-Cheng Ling (pp. 932-936).

Thiophene was introduced as an additive in detonation-assisted chemical vapor deposition to investigate the effect of sulfur on the growth of carbon nanotubes. The results reveal that sulfur promoted the growth of hollow tubes, instead of bamboo-like carbon nanotubes without sulfur addition. Structural characterization of products indicates that the dynamic reshaping of the catalyst assisted bamboo-like carbon nanotube growth and the bamboo knots preferentially nucleated on the Ni–graphite step edges. It is suggested that sulfur suppressed the bamboo knot growth through blocking the step sites. The findings are important for understanding of nanotube growth mechanism and the role of sulfur often involved in catalytic reactions.

Keywords: Carbon nanotubes; Sulfur; Dynamic reshaping; Bamboo knots

Surface of Zn–Mn–O and its role in room temperature ferromagnetism: An XPS analysis by Dušan Milivojević; Branka Babić-Stojić; Janez Kovač (pp. 937-943).

The existence of ferromagnetism in Zn–Mn–O semiconductor samples and dependence on the preparation condition were investigated. We systematically examined the samples with manganese concentration ranging from 0 to 10 at.%, prepared by a solid state reaction route using (ZnC₂O₄·2H₂O)1−_x and (MnC₂O₄·2H₂O)_x as precursors. Thermal treatment was carried out in air at temperatures ranging from 400 to 900°C. The samples were investigated by X-ray diffraction, transmission electron microscopy, magnetization measurements and XPS spectroscopy. XPS surface composition, chemical analysis and depth profiling were successfully employed on powder revealing the chemical composition at the surface of the grains and underneath. The present investigation suggests that physical properties and observed room temperature ferromagnetism might be due to grain surface effects. It seems that the ferromagnetic phase is correlated with oxygen build up at the surface.

Keywords: PACS; 75.50.Pp; 81.40.Rs; 81.70.Jb; 82.80.PvZnO; Magnetic semiconductors; Room temperature ferromagnetism; XPS

Photocatalysis and wave-absorbing properties of polyaniline/TiO₂ microbelts composite by in situ polymerization method by Qiaoling Li; Cunrui Zhang; Jianqiang Li (pp. 944-948).

Polyaniline (PANI)/TiO₂ composite is prepared by in situ polymerization of polyaniline on the surface of TiO₂ template obtained by the sol–gel process via cotton template. The TiO₂ microbelts are prepared by sol–gel method using the absorbent cotton as template for the first time. Then the TiO₂ microtubules are used as template for the preparation of polyaniline/TiO₂ composites. The structure, morphology and properties of the composites are characterized with scanning electron microscope (SEM), IR, Net-wok Analyzer. A possible formation mechanism of TiO₂ microtubules and polyaniline/TiO₂ composites has been proposed. The effect of the mol ratio of polyaniline/TiO₂ on the microwave loss properties and photocatalysis properties of the composites is investigated.

Keywords: TiO; ₂; Polyaniline; Microwave absorbing; Photocatalysis

Ge/Sb₂Te₃ nanocomposite multilayer films for high data retention phase-change random access memory application by Changzhou Wang; Jiwei Zhai; Zhitang Song; Fei Shang; Xi Yao (pp. 949-953).

The amorphous-to-crystalline transition of Ge/Sb₂Te₃ nanocomposite multilayer films with various thickness ratios of Ge to Sb₂Te₃ were investigated by utilizing in situ temperature-dependent film resistance measurements. The crystallization temperature and activation energy for the crystallization of the multilayer films increased with the increase in thickness ratio of Ge to Sb₂Te₃. The difference in sheet resistance between amorphous and crystalline states could reach as high as 10⁴Ω/□. The crystallization temperature and activation energy for the crystallization of Ge/Sb₂Te₃ nanocomposite multilayer films was proved to be larger than that of conventional Ge₂Sb₂Te₅ film, which ensures a better data retention for phase-change random access memory (PCRAM) use. A data retention temperature for 10 years of the amorphous state [Ge (2nm)/Sb₂Te₃ (3nm)]₄₀ film was estimated to be 165°C. Transmission electron microscopy (TEM) images revealed that Ge/Sb₂Te₃ nanocomposite multilayer films had layered structures with clear interfaces.

Keywords: PACS; 62.23.Pq; 68.65.Ac; 61.50.Ks; 68.60.Dv; 64.60.EjNanocomposite; Multilayer films; Data retention; Phase-change random access memory

Pulsed laser deposition of fluoride glass thin films by Dimitri Ganser; Jens Gottmann; Uwe Mackens; Ulrich Weichmann (pp. 954-959).

The development of integrated waveguide lasers for different applications such as marking, illumination or medical technology has become highly desirable. Diode pumped planar waveguide lasers emitting in the green visible spectral range, e.g. thin films from praseodymium doped fluorozirconate glass matrix (called ZBLAN, owing to the main components ZrF₄, BaF₂, LaF₃, AlF₃ and NaF) as the active material pumped by a blue laser diode, have aroused great interest. In this work we have investigated the deposition of Pr:ZBLAN thin films using pulsed laser radiation of λ=193 and λ=248nm. The deposition has been carried out on MgF₂ single crystal substrates in a vacuum chamber by varying both processing gas pressure and energy fluence. The existence of an absorption line at 210nm in Pr:ZBLAN leads to absorption and radiative relaxation of the absorbed laser energy of λ=193nm preventing the evaporation of target material. The deposited thin films consist of solidified and molten droplets and irregular particulates only. Furthermore, X-ray radiation has been applied to fluoride glass targets to enhance the absorption in the UV spectral region and to investigate the deposition of X-ray treated targets applying laser radiation of λ=248nm. It has been shown that induced F-centres near the target surface are not thermally stable and can be easily ablated. Therefore, λ=248nm is not suitable for evaporation of Pr:ZBLAN.

Keywords: Pulsed laser deposition; Thin films; Praseodymium; Fluoride glass; Induced absorption; X-ray irradiation

Surface textured ZnO:Al thin films by pulsed DC magnetron sputtering for thin film solar cells applications by W.T. Yen; Y.C. Lin; J.H. Ke (pp. 960-968).

Transparent conducting thin films of ZnO:Al (Al-doped ZnO, AZO) were prepared via pulsed DC magnetron sputtering with good transparency and relatively lower resistivity. The AZO films with 800nm in thickness were deposited on soda-lime glass substrates keeping at 473K under 0.4Pa working pressure, 150W power, 100μs duty time, 5μs pulse reverse time, 10kHz pulse frequency and 95% duty cycle. The as-deposited AZO thin films has resistivity of 6.39×10⁻⁴Ωcm measured at room temperature with average visible optical transmittance, T_total of 81.9% under which the carrier concentration and mobility were 1.95×10²¹cm⁻³ and 5.02cm²V⁻¹s⁻¹, respectively. The films were further etched in different aqueous solutions, 0.5% HCl, 5% oxalic acid, 33% KOH, to conform light scattering properties. The resultant films etched in 0.5% HCl solution for 30s exhibited high T_total=78.4% with haze value, H_T=0.1 and good electrical properties, ρ=8.5×10⁻⁴Ωcm while those etched in 5% oxalic acid for 150s had desirable H_T=0.2 and relatively low electrical resistivity, ρ=7.9×10⁻⁴Ωcm. However, the visible transmittance, T_total was declined to 72.1%.

Keywords: Al-doped ZnO; Surface textured; Light-trapping structure; Haze value; Pulsed DC magnetron sputtering

Elucidating surface properties of dry-etched ZnO using H₂/CH₄ and H₂/CH₄/Ar plasma by Kuang-Po Hsueh (pp. 969-973).

This paper reports a study of reactive ion etching (RIE) of n-ZnO in H₂/CH₄ and H₂/CH₄/Ar gas mixtures. Variables in the experiment were gas flow ratios, radio-frequency (rf) plasma power, and total pressure. Structural and electrical parameters of the etched surfaces and films were determined. Both the highest surface roughness and highest etching rate of ZnO films were obtained with a maximum rf power of 300W, but at different gas flow ratios and working pressures. These results were expected because increasing the rf power increased the bond-breaking efficiency of ZnO. The highest degree of surface roughness was a result of pure physical etching by H₂ gas without mixed CH₄ gas. The highest etching rate was obtained from physical etching of H₂/Ar species associated with chemical reaction of CH₄ species. Additionally, the H₂/CH₄/Ar plasma treatment drastically decreased the specific contact and sheet resistance of the ZnO films. These results indicated that etching the ZnO film had roughened the surface and reduced its resistivity to ohmic contact, supporting the application of a roughened transparent contact layer (TCL) in light-emitting diodes (LEDs).

Keywords: Zinc oxide; Surface roughness; Dry etching

Synthesis and bactericidal ability of Ag/TiO₂ composite films deposited on titanium plate by Lixiang Mai; Dawei Wang; Sheng Zhang; Yongjian Xie; Chunming Huang; Zhiguang Zhang (pp. 974-978).

In this study, we develop a bactericidal coating material for micro-implant, TiO₂ films with Ag deposited on were prepared on titanium plates by sol–gel process. Their anti-microbial properties were analyzed as a function of the annealed temperature using Escherichia coli as a benchmark microorganism. Ag nanoparticles deposited on TiO₂ film were of metallic nature and could grow to larger ones when the annealed temperature increased. The results indicated that the smaller size of Ag nanoparticles, the better bactericidal ability. On the other hand, the positive antibacterial effect of TiO₂ enhanced the bactericidal effect of Ag.

Keywords: Thin films; Sol–gel preparation; Titanium dioxide; Bactericidal ability; Ag nanoparticles

The effect of surface nanocrystallization on plasma nitriding behaviour of AISI 4140 steel by Yang Li; Liang Wang; Dandan Zhang; Lie Shen (pp. 979-984).

A plastic deformation surface layer with nanocrystalline grains was produced on AISI 4140 steel by means of surface mechanical attrition treatment (SMAT). Plasma nitriding of SMAT and un-SMAT AISI 4140 steel was carried out by a low-frequency pulse excited plasma unit. A series of nitriding experiments has been conducted at temperatures ranging from 380 to 500°C for 8h in an NH₃ gas. The samples were characterized using X-ray diffraction, scanning electron microscopy, optical microscopy and Vickers microhardness tester. The results showed that a much thicker compound layer with higher hardness was obtained for the SMAT samples when compared with un-SMAT samples after nitriding at the low temperature. In particular, plasma nitriding SMAT AISI 4140 steel at 380°C for 8h can produced a compound layer of 2.5μm thickness with very high hardness on the surface, which is similar to un-SMAT samples were plasma nitrided at approximately 430°C within the same time.

Keywords: Plasma nitriding; AISI 4140 steel; Nanocrystalline materials

Morphology and photoluminescence study of electrodeposited ZnO films by Sheng-Nan Sun; B. Marí; Hong-Lin Wu; M. Mollar; Hai-Ning Cui (pp. 985-989).

ZnO films on ITO substrates and Au coated ITO substrates were fabricated by using electrodeposition technique. We carried out the experiments by adjusting the concentration of solution, potential, substrate, and temperature. The effect of temperature on the growth of the film has been examined. SEM images have shown that there are several kinds of grown competitions for the deposition of ZnO films, but three kinds of them are dominant. One is the discrete hexagonal column structure, the other is the pentagonal structure, and the third one is of well-oriented hexagonal columns with well-aligned structure. The explanation on the grown competition is discussed. ZnO hexagonal column structures with well-aligned and well-perpendicular to the surface were successfully obtained on Au/ITO substrate in aqueous solvent of electrolyte. Clearly the main columns in the film were obtained by increasing the temperature. Its photoluminescence (PL) study at low temperature exhibited the optical properties as wurtzite ZnO and indicated the existence of macrocrystalline ZnO. A better quality of ZnO columnar structures after annealing was demonstrated from PL analysis and discussion on the existence of 370nm, 384nm and 639nm in the emission bands before and after annealing.

Keywords: ZnO films; Well-perpendicular columns; Electrodeposition; Photoluminescence

Experimental and computational study on hydrolysis and condensation kinetics of γ-glycidoxypropyltrimethoxysilane (γ-GPS) by Lixia Yang; Jun Feng; Wenguang Zhang; Jun-e Qu (pp. 990-996).

Since the amount of silanol units in the hydrolysis solution directly determines the interfacial adhesive strength and corrosion resisting property of self-assembled silane films, therefore, it is very essential to have a deep understanding of hydrolysis behaviors of SCAs (silane coupling agents). Conductivity measurement, RA-IR measurement and density functional theory (DFT) calculation was applied to the study of the hydrolysis and condensation kinetics of γ-glycidoxypropyltrimethoxysilane (γ-GPS) under near-neutral and acidic conditions. The results indicated that a critical point existed at about 50h, dividing the entire hydrolysis period into two stages: Stage 1 (S1) and Stage 2 (S2). In S1, the first step hydrolysis reaction prevailed, while the second and third step hydrolysis reactions only played minor roles. The pH value of the hydrolysis solution imposed little influence on the reactions occurring in the solution. However, in S2, pH value exerted a significant influence on the hydrolysis and condensation reactions, based on which there was an optimum pH value range. The results of DFT calculation were consistent with the experimental measurements. Hitherto, a validate method was proposed to simulate the reactions occurring in the hydrolysis solution.

Keywords: Conductivity; γ-GPS; Hydrolysis; Density functional calculation

Upon a magnetic composite preparation based on magnetite and poly(succinimide)-b-poly(ethylene glycol) shell by Aurica P. Chiriac; Loredana E. Niţă; Iordana Neamţu; Vasile Badescu (pp. 997-1001).

Taking into account that magnetic particles with suitable surface characteristics have a high potential for the use in a lot of in vitro and in vivo applications, in the study is presented the in situ preparation of a core-shell magnetic composite based on the magnetite core and the shell composed from the poly(succinimide)-b-poly(ethylene glycol) copolymer. The average particle size of the synthesized magnetic microspheres is in the range of 6.5–8.8μm with a magnetite content of around 11%. The saturation magnetization of the microspheres was found 26.8emu/g, the magnetic microspheres being characterized by superparamagnetic properties. The particles have combined properties of high magnetic saturation and biocompatibility and interactive functions at the surface through the block copolymer shell. The surface of the magnetic particles has also the possibility for further functionalization or the attachment of various bioactive molecules after the hydrolysis of the succinimide cycle and the resulting carboxylic group.

Keywords: Poly(succinimide)-b-poly(ethylene glycol); Magnetic composite

Calculated influence of work function on SE escape probability and Secondary Electron Emission yield by Jacques Cazaux (pp. 1002-1009).

The influence of changes of the work function, ϕ, or electron affinity, χ, on the escape probability, A, of Secondary Electrons, SE, is derived from their angular and energy distributions, respectively ∂ δ/∂ α and ∂ δ/∂ E_k. Based on the evaluation of the spectral distribution of inner SEs, the present approach quantifies the dominant role of potential barrier on the SE emission and its change with surface treatments or thin film deposits. For instance it is shown that a 1eV-increase of ϕ for Au leads to a decrease of A, and then of SE emission yield, δ, of about 50% while a 0.4eV-increase of χ for potassium chloride induces a decrease of a factor 4 for A and then for the SEE yield δ. These results are summarized by empirical expressions of form A/ A°=( ϕ/ ϕ°)⁻³ for Au and A/ A°=( χ/ χ°)^−3/2 for KCl. Applied here to an insulating sample and to a metal, the present approach may be easily transposed to any kind of material of known Fermi energy and work function, metals, or known affinity, semiconducting and insulating samples. The large SEE yield values of inorganic insulators relative to that of metals are explained by larger values of their escape probability A – KCl: A°∼25% for χ°=0.6eV; Au: A°∼4% for ϕ°=3.5eV – combined to larger SE attenuation lengths and despite a less SE generation factor. This approach underlines the significant role of A on the large deviations between SEEY data as reported in literature and a strategy combining in situ δ and ϕ measurements is suggested to partly compensate the corresponding dispersion of experimental results. The present approach may be transposed to other energetic projectiles such as X-rays or ions and some practical consequences related to Scanning Electron Microscopy, mechanisms of contamination and crystalline contrasts, are pointed out.

Keywords: PACS; 79.20Hx; 61.16Bg; 73.23.Ps; 73.30.+y; 81.05.−tSecondary electron emission; Spectral and angular distribution of secondary electrons; Scanning electron microscopy; Contamination effect; Crystalline contrast; Thin films

Green chemical functionalization of multiwalled carbon nanotubes with poly(ɛ-caprolactone) in ionic liquids by Yingkui Yang; Shengqiang Qiu; Chengen He; Wenjie He; Linjuan Yu; Xiaolin Xie (pp. 1010-1014).

Multiwalled carbon nanotubes (MWNTs) have been successfully functionalized by free radical addition of 4,4′-azobis(4-cyanopentanol) in aqueous media to generate the terminal-hydroxyl-modified MWNTs (MWNT–OH), followed by surface-initiated in situ ring-opening polymerization of ɛ-caprolactone in 1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF₄) to obtain poly(ɛ-caprolactone)-grafted MWNTs (MWNT- g-PCL). Spectroscopic methods in conjunction with electron microscopy clearly revealed that hairy PCL chains were chemically attached to the surface of MWNTs to form core–shell nanostructures with the latter as core and the former as shell. With increasing polymerization time from 2 to 8h, the amount of the grafted-PCL synthesized in BmimBF₄ varies from 30.6 to 62.7wt%, which is clearly higher than that (41.5wt%) obtained in 1,2-dichlorobenzene under comparable conditions (8h). The proposed methodology here uses water and room temperature ionic liquids (RTILs) as the reaction media and promises a green chemical process for functionalizing nanotubes.

Keywords: Carbon nanotubes; Room temperature ionic liquids; Poly(ɛ-caprolactone); Green functionalization

Fabrication of ultrahydrophobic poly(lauryl acrylate) brushes on silicon wafer via surface-initiated atom transfer radical polymerization by Esra Öztürk; Eylem Turan; Tuncer Caykara (pp. 1015-1020).

In this report, ultrahydrophobic poly(lauryl acrylate) [poly(LA)] brushes were synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP) of lauryl acrylate (LA) in N,N-dimethylformamide (DMF) at 90°C. The formation of ultrahydrophobic poly(LA) films, whose thickness can be turned by changing polymerization time, is evidenced by using the combination of ellipsometry, X-ray photoelectron spectroscopy (XPS), grazing angle attenuated total reflectance-Fourier transform infrared spectroscopy (GATR-FTIR), atomic force microscopy (AFM), gel permeation chromatography (GPC), and water contact angle measurements. The SI-ATRP can be conducted in a well-controlled manner, as revealed by the linear kinetic plot, linear evolution of number-average molecular weights (M¯n) versus monomer conversions, and the relatively narrow PDI (<1.28) of the grafted poly(LA) chains. The calculation of grafting parameters from experimental measurements indicated the synthesis of densely grafted poly(LA) films and allowed us to predict a “brushlike” conformation for the chains in good solvent. The poly(LA) brushes exhibited high water contact angle of 163.3±2.8°.

Keywords: ATRP; Polymer brushes; Ultrahydrophobic surfaces

Surface plasmon resonance biosensor modified with multilayer silver nanoparticles films by Yanling Chen; Bingyang Dong; Wenyun Zhou (pp. 1021-1026).

We alternately deposited negatively charged Ag-(3-mercaptopropionic acid) (Ag-MPA) sol and positively charged poly-(diallyldimethylammonium) (PDDA) on gold substrate modified with 4-aminothiophenol (4-ATP), through electrostatic layer-by-layer (LBL) self-assembly. We characterized the prepared three-dimensional Ag/PDDA multilayer films by surface plasmon resonance (SPR) and atomic force microscope (AFM). The thickness of each film in the multilayer films, the deposition effect of Ag nanoparticles, and the processing of DNA adsorption are characterized by SPR. AFM characterization shows that DNA/3(PDDA/Ag)/4-ATP composite is uniformly and firmly distributed on the surface of gold films. Compared with other sensors, gentamicin could be highly sensitively measured by DNA/3(PDDA/Ag)/4-ATP/Au sensor. There is a good linear relationship in the concentration range of 5×10⁻⁸ to 1×10⁻⁴mol/L. The linear equation is found to be Δ θ_SPR=1.3521×10⁻⁵ c+0.08641 (the correlation coefficient is 0.9983) with detection limit of 1×10⁻⁹mol/L. Since such LBL assembly film is simple to prepare, the work described here provides an effective method for studying small molecule drugs on SPR.

Keywords: SPR; Ultrathin multilayer films; Silver nanoparticle; Biosensor; DNA; Gentamicin

Effective electrodeposition of Co–Ni–Cu alloys nanoparticles in the presence of alkyl polyglucoside surfactant by Setia Budi; A.R. Daud; S. Radiman; Akrajas Ali Umar (pp. 1027-1033).

The effect of alkyl polyglucoside (APG) surfactant on the electrodeposition Co–Ni–Cu alloys nanoparticles has been investigated. In a typical electrodeposition experiment, it was found that as prepared Co–Ni–Cu alloys nanoparticles characteristics, such as size homogeneity, density, dispersion on the electrode substrate and the chemicals composition, depended strongly on the concentration of APG used in the reaction as well as the applied deposition potential. For the case of chemicals composition, low APG concentration (below CMC) was found to be effective for the preparation of excellent composition of the nanoalloys. Meanwhile, for the case of size homogeneity, density, and dispersion on the surface, high APG concentration (above CMC) and high deposition potential were preferred. It was also found that, at concentration above the CMC, the APG surfactant showed a metals ions deposition inhibition characteristic that caused increasing in the electrodeposition overpotential of the entire metals ions, namely cobalt, nickel and copper. As the result the copper was found to place a high percentage in the nanoalloys deposits. Owing to its simple procedure in controlling the composition and the nanoalloys growth characteristic, present approach should find a potential application in preparing Co–Ni–Cu magnetic nanoparticles for used in currently existing applications.

Keywords: Co–Ni–Cu nanoparticle; Electrodeposition; Cyclic voltammetry; Alkyl polyglucoside; Critical micelle concentration

The relationship between the adhesion work, the wettability and composition of the surface layer in the systems polymer/aqueous solution of anionic surfactants and alcohol mixtures by Anna Zdziennicka; Bronisław Jańczuk (pp. 1034-1042).

Measurements of advancing contact angle ( θ) were carried out on polytetrafluoroethylene (PTFE) and polymethylmethacrylate (PMMA) for aqueous solution of sodium dodecyl sulfate (SDDS) mixtures with methanol, ethanol and propanol in the range of SDDS concentration from 10⁻⁵ to 10⁻²M, and for sodium hexadecyl sulfonate (SHS) with the same alcohols at the SHS concentration ranging from 10⁻⁵ to 8×10⁻⁴M at 293K. The concentration of methanol, ethanol and propanol used for measurements varied from 0 to 21.1, 11.97 and 6.67M, respectively. On the basis of the contact angles the critical surface tension of PTFE and PMMA wetting was determined by using for this purpose the relationship between the adhesion and the surface tension and cos θ and surface tension both at constant alcohol and surfactant concentration, respectively. The obtained contact angles were also used in the Young Dupre’ equation for calculations of the adhesion work of aqueous solution of mixtures of anionic surfactants and short chain alcohols to PTFE and PMMA surface. The adhesion work calculated in this way was compared to that of the particular components of aqueous solution to these surfaces determined on the basis of the surface tension components and parameters of the surface tension of the surface active agents, water, PTFE and PMMA from van Oss et al. equation. The calculated adhesion work was discussed in the light of the concentration of surface active agents at polymer–water and water–air interface determined from Lucassen-Reynders, Gibbs and Guggenheim-Adam equations.

Keywords: Polytetrafluoroethylene; Polymethylmethacrylate; Wettability; Anionic surfactants; Adsorption; Work of adhesion

Atomic layer deposition of HfO₂: Effect of structure development on growth rate, morphology and optical properties of thin films by Raul Rammula; Jaan Aarik; Hugo Mändar; Peeter Ritslaid; Väino Sammelselg (pp. 1043-1052).

HfO₂ films were grown by atomic layer deposition from HfCl₄ and H₂O on Si(100), Si(111) and amorphous SiO₂ substrates at 180–750°C and the effect of deposition temperature and film thickness on the growth rate and optical properties of the film material was studied. Crystallization, texture development and surface roughening were demonstrated to result in a noticeable growth rate increase with increasing film thickness. Highest surface roughness values were determined for the films deposited at 350–450°C on all substrates used. The density of the film material increased with the concentration of crystalline phase but, within experimental uncertainty, was independent of orientation and sizes of crystallites in polycrystalline films. Refractive index increased with the material density. In addition, the refractive index values that were calculated from the transmission spectra depended on the surface roughness and crystallite sizes because the light scattering, which directly influenced the extinction coefficient, caused also a decrease of the refractive index determined in this way.

Keywords: Hafnium dioxide; Atomic layer deposition (ALD); Structure; Crystallization; Topography

A close correlation between induced ferromagnetism and oxygen deficiency in Fe doped In₂O₃ by R.K. Singhal; A. Samariya; Sudhish Kumar; S.C. Sharma; Y.T. Xing; U.P. Deshpande; T. Shripathi; E. Saitovitch (pp. 1053-1057).

We report on the reversible manipulation of room temperature ferromagnetism in Fe (5%) doped In₂O₃ polycrystalline magnetic semiconductor. The X-ray diffraction and photoemission measurements confirm that the Fe ions are well incorporated into the lattice, substituting the In³⁺ ions. The magnetization measurements show that the host In₂O₃ has a diamagnetic ground state, while it shows weak ferromagnetism at 300K upon Fe doping. The as-prepared sample was then sequentially annealed in hydrogen, air, vacuum and finally in air. The ferromagnetic signal shoots up by hydrogenation as well as vacuum annealing and bounces back upon re-annealing the samples in air. The sequence of ferromagnetism shows a close inter-relationship with the behavior of oxygen vacancies ( V_o). The Fe ions tend to a transform from 3+ to 2+ state during the giant ferromagnetic induction, as revealed by photoemission spectroscopy. A careful characterization of the structure, purity, magnetic, and transport properties confirms that the ferromagnetism is due to neither impurities nor clusters but directly related to the oxygen vacancies. The ferromagnetism can be reversibly controlled by these vacancies while a parallel variation of carrier concentration, as revealed by resistance measurements, appears to be a side effect of the oxygen vacancy variation.

Keywords: Dilute magnetic semiconductors; Oxygen vacancies; X-ray photoelectron spectroscopy

Thermal stability of alumina thin films containing γ-Al₂O₃ phase prepared by reactive magnetron sputtering by J. Musil; J. Blažek; P. Zeman; Š. Prokšová; M. Šašek; R. Čerstvý (pp. 1058-1062).

The paper reports on thermal stability of alumina thin films containing γ-Al₂O₃ phase and its conversion to a thermodynamically stable α-Al₂O₃ phase during a post-deposition equilibrium thermal annealing. The films were prepared by reactive magnetron sputtering and subsequently post-deposition annealing was carried out in air at temperatures ranging from 700°C to 1150°C and annealing times up to 5h using a thermogravimetric system. The evolution of the structure was investigated by means of X-ray diffraction after cooling down of the films. It was found that (1) the nanocrystalline γ-Al₂O₃ phase in the films is thermally stable up to 1000°C even after 5h of annealing, (2) the nanocrystalline θ-Al₂O₃ phase was observed in a narrow time and temperature region at ≥1050°C, and (3) annealing at 1100°C for 2h resulted in a dominance of the α-Al₂O₃ phase only in the films with a sufficient thickness.

Keywords: Al; ₂; O; ₃; (alumina); Annealing; Thermal stability; Nanocrystalline material; Sputtering

Structural, electrical and optical properties of Ga-doped ZnO films on PET substrate by Byeong-Guk Kim; Jeong-Yeon Kim; Seok-Jin Lee; Jae-Hwan Park; Dong-Gun Lim; Mun-Gi Park (pp. 1063-1067).

The effects of O₂ plasma pretreatment on the properties of Ga-doped ZnO films on PET substrate were studied. Ga-doped ZnO films were fabricated by RF magnetron sputtering process. To improve surface energy and adhesion of PET substrate, O₂ plasma pretreatment process was used prior to GZO sputtering. With increasing O₂ plasma treatment time, the contact angle decreases and the RMS surface roughness increases significantly. The transmittance of GZO films on PET substrate in a wavelength of 550nm was 70–84%. With appropriate O₂ plasma treatment, the resistivity of GZO films on PET substrate was 3.4×10⁻³Ωcm.

Keywords: Transparent conducting oxide; ZnO; O; ₂; plasma; Polyethylene terephthalate (PET)

Favorable recycling photocatalyst TiO₂/CFA: Effects of loading percent of TiO₂ on the structural property and photocatalytic activity by Jian-wen Shi; Shao-hua Chen; Zhi-long Ye; Shu-mei Wang; Peng Wu (pp. 1068-1074).

A series of photocatalysts TiO₂/CFA were prepared using coal fly ash (CFA), waste discharged from coal-fired power plant, as substrate, and then these photocatalysts were characterized by scanning electron microscope, X-ray diffraction analysis, nitrogen adsorption test and ultraviolet–visible absorption analysis. The effects of loading percent of TiO₂ on the photocatalytic activity and re-use property of TiO₂/CFA were evaluated by the photocatalytic decoloration and mineralization of methyl orange solution. The results show that the pore volume and the specific surface area of the TiO₂/CFA both increased with the increase in the loading percent of TiO₂, which improved the photocatalytic activity of TiO₂/CFA. However, when the loading percent of TiO₂ was too high (up to 54.51%), superfluous TiO₂ was easy to break away from CFA in the course of water treatment, which was disadvantaged to the recycling property of TiO₂/CFA. In this study, the optimal loading percent of TiO₂ was 49.97%, and the efficiencies of photocatalytic decoloration and mineralization could be maintained above 99% and 90%, respectively, when the photocatalyst was used repeatedly, without any decline, even at the sixth cycle.

Keywords: Titania; Coal fly ash; Loading percent; Photocatalytic activity

Near field properties of nanoparticle arrays fabricated by laser annealing of thin Au and Ag films by S. Imamova; N. Nedyalkov; A. Dikovska; P. Atanasov; M. Sawczak; R. Jendrzejewski; G. Śliwiński; M. Obara (pp. 1075-1079).

In this work we show the properties of the electromagnetic field in the vicinity of a monolayer nanoparticle array on SiO₂ substrate. The nanoparticle array is produced by a simple experimental procedure, where thin gold and silver films are deposited on a substrate by pulsed laser deposition technique and they are annealed by nanosecond laser pulses. At certain conditions the laser annealing leads to a homogeneous decomposition of the film into nanoparticles with diameters in the range of few tens of nanometers. Using FDTD simulations the near field distribution in array structures taken from SEM images are obtained. The distribution shows presence on “hot spots” where the near field intensity is enhanced more than two orders of magnitude compared to the incident one. The existence of enhanced field intensity is assumed to be the main reason on enhancement of the Raman scattering signal obtained experimentally using the produced structures as active substrates.

Keywords: Laser nanostructuring; Near field; SERS

Investigation of etch characteristics of non-polar GaN by wet chemical etching by Hsiao-Chiu Hsu; Yan-Kuin Su; Shin-Hao Cheng; Shyh-Jer Huang; Jia-Ming Cao; Kuan-Chun Chen (pp. 1080-1083).

We characterized the surface defects in a-plane GaN, grown onto r-plane sapphire using a defect-selective etching (DSE) method. The surface morphology of etching pits in a-plane GaN was investigated by using different combination ratios of H₃PO₄ and H₂SO₄ etching media. Different local etching rates between smooth and defect-related surfaces caused variation of the etch pits made by a 1:3 ratio of H₃PO₄/H₂SO₄ etching solution. Analysis results of surface morphology and composition after etching by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) demonstrated that wet chemical etching conditions could show the differences in surface morphology and chemical bonding on the a-plane GaN surface. The etch pits density (EPD) was determined as 3.1×10⁸cm⁻² by atom force microscopy (AFM).

Keywords: Gallium nitride; Non-polar; Wet chemical etching; X-ray photoelectron spectroscopy

Catalyst-free growth of well-aligned arsenic-doped ZnO nanowires by chemical vapor deposition method by Q.J. Feng; L.Z. Hu; H.W. Liang; Y. Feng; J. Wang; J.C. Sun; J.Z. Zhao; M.K. Li; L. Dong (pp. 1084-1087).

ZnO nanowires with different arsenic concentration were grown on Si (100) substrates by chemical vapor deposition method without using catalyst. Zn/GaAs mixed powders were used as Zn and As source, respectively. Oxygen was used as oxidant. The images of scanning electron microscope show that the arsenic-doped ZnO nanowires with preferred c-axial orientation were obtained, which is in well accordance with the X-ray diffraction analysis. The arsenic related acceptor emission was observed in the photoluminescence spectra at 11K for all arsenic-doped ZnO samples. This method for the preparation of arsenic-doped ZnO nanowires may open the way to realize the ZnO nanowires based light-emitting diode and laser diode.

Keywords: ZnO nanowires; Arsenic; Chemical vapor deposition; Photoluminescence

Influence of the crystal orientation on the electrical properties of AlN thin films on LTCC substrates by A. Bittner; A. Ababneh; H. Seidel; U. Schmid (pp. 1088-1091).

In this study, the influence of the crystal orientation on the electrical properties of sputter deposited aluminium nitride (AlN) thin films on low temperature co-fired ceramics (LTCC) substrates is investigated. The degree of c-axis orientation can be tailored by the deposition conditions such as plasma power, gas pressure and gas composition in the deposition chamber. Due to the large surface roughness of LTCC substrates ( R_a=∼0.4μm) the quality of thin films is lower compared to silicon. Between areas of columnar grains arranged perpendicular to the LTCC surface, defects like voids are generated due to the wavy surface characteristics. The impact of crystal orientation and temperature up to 400°C on the electrical performance is evaluated, as these layers are targeted as potential candidates for dielectric heat spreaders on multilayered ceramic substrates for high frequency applications. These AlN thin films having a good c-axis orientation exhibit lower leakage current levels over the complete temperature range compared to those with a poor alignment with respect to this crystallographic plane. The leakage current behaviour, however, is dominated according to the Pool–Frenkel electron emission independent of the degree of c-axis orientation.

Keywords: AlN; Thin film; Sputter deposition; Conduction mechanism; Temperature activation; LTCC substrates

Silver nanoparticles on amidoxime fibers for photo-catalytic degradation of organic dyes in waste water by Zhi-Chuan Wu; Yong Zhang; Ting-Xian Tao; Lifeng Zhang; Hao Fong (pp. 1092-1097).

Herein we report that a new photo-catalyst of silver nanoparticles attached on the surface of amidoxime fibers was developed and evaluated. The nanoparticles had different sizes from tens to hundreds of nanometers and varied shapes of cube, plate, and sphere; and there were coordination interactions between the nanoparticles and the amidoxime fibers. The developed photo-catalyst demonstrated high activities for degradation of an organic dye of methyl orange, particularly under sunlight; and the catalyst could be re-activated for several times by simple tetrahydrofuran treatment. The results also suggested that the silver nanoparticles initiated and/or mediated the photo-oxidation reaction of methyl orange through localized surface plasmon resonance under sunlight, and the photo-catalytic activities were primarily determined by sizes and/or surface-to-mass ratios instead of shapes of the silver nanoparticles.

Keywords: Silver nanoparticle; Amidoxime fiber; Methyl orange; Photo-catalytic degradation

Enhancement of surface mechanical properties by using TiN[BCN/BN]_n/c-BN multilayer system by H. Moreno; J.C. Caicedo; C. Amaya; J. Muñoz-Saldaña; L. Yate; J. Esteve; P. Prieto (pp. 1098-1104).

The aim of this work is to improve the mechanical properties of AISI 4140 steel substrates by using a TiN[BCN/BN]_n/c-BN multilayer system as a protective coating. TiN[BCN/BN]_n/c-BN multilayered coatings via reactive r.f. magnetron sputtering technique were grown, systematically varying the length period ( Λ) and the number of bilayers ( n) because one bilayer ( n=1) represents two different layers ( t_BCN+ t_BN), thus the total thickness of the coating and all other growth parameters were maintained constant. The coatings were characterized by Fourier transform infrared spectroscopy showing bands associated with h-BN bonds and c-BN stretching vibrations centered at 1400cm⁻¹ and 1100cm⁻¹, respectively. Coating composition and multilayer modulation were studied via secondary ion mass spectroscopy. Atomic force microscopy analysis revealed a reduction in grain size and roughness when the bilayer number ( n) increased and the bilayer period decreased. Finally, enhancement of mechanical properties was determined via nanoindentation measurements. The best behavior was obtained when the bilayer period ( Λ) was 80nm ( n=25), yielding the relative highest hardness (∼30GPa) and elastic modulus (230GPa). The values for the hardness and elastic modulus are 1.5 and 1.7 times greater than the coating with n=1, respectively. The enhancement effects in multilayered coatings could be attributed to different mechanisms for layer formation with nanometric thickness due to the Hall–Petch effect; because this effect, originally used to explain increased hardness with decreasing grain size in bulk polycrystalline metals, has also been used to explain hardness enhancements in multilayered coatings taking into account the thickness reduction at individual single layers that make up the multilayered system. The Hall–Petch model based on dislocation motion within layered and across layer interfaces has been successfully applied to multilayered coatings to explain this hardness enhancement.

Keywords: PACS; 61.05.c; 62.20.Qp; 68.65.AcMultilayer coatings; Magnetron sputtering; Mechanical properties

Thermal annealing dependence of some optical properties of plasma-modified porous silicon by Be. Benyahia; N. Gabouze; L. Guerbous; Br. Mahmoudi; H. Menari (pp. 1105-1111).

The photoluminescence and reflectance of porous silicon (PS) with and without hydrocarbon (CH_x) deposition fabricated by plasma enhanced chemical vapour deposition (PECVD) technique have been investigated. The PS samples were then, annealed at temperatures between 200 and 800°C. The influence of thermal annealing on optical properties of the hydrocarbon layer/porous silicon/silicon structure (CH_x/PS/Si) was studied by means of photoluminescence (PL) measurements, reflectivity and ellipsometry spectroscopy. The composition of the PS surface was monitored by transmission Fourier transform infrared (FTIR) spectroscopy. Photoluminescence and reflectance measurements were carried out before and after annealing on the carbonized samples for wavelengths between 250 and 1200nm. A reduction of the reflectance in the ultraviolet region of the spectrum was observed for the hydrocarbon deposited polished silicon samples but an opposite behaviour was found in the case of the CH_x/PS ones. From the comparison of the photoluminescence and reflectance spectra, it was found that most of the contribution of the PL in the porous silicon came from its upper interface. The PL and reflectance spectra were found to be opposite to one another. Increasing the annealing temperature reduced the PL intensity and an increase in the ultraviolet reflectance was observed. These observations, consistent with a surface dominated emission process, suggest that the surface state of the PS is the principal determinant of the PL spectrum and the PL efficiency.

Keywords: PACS; 78.55.Mb; 81.15.Gh; 81.70.Fy; 82.80.GkPorous silicon; Hydrocarbon layer; Photoluminescence; Reflectance

Study on the surface properties of wood/polyethylene composites treated under plasma by Yang Liu; Yan Tao; Xinying Lv; Yanhua Zhang; Mingwei Di (pp. 1112-1118).

Wood/polyethylene (PE) composites are widely used in many fields for its excellent properties, but they are hard to adhere for the surface lacking of polarity. So low-pressure glow discharge of air plasma was used to improve the adhesion properties of wood/PE composites. The composites were treated by plasma under different discharge power. And the changes on the surface properties of the treated and untreated composites were studied by contact angle, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS) analysis. The measurement showed that the contact angle decreased after plasma treatment, and the contact angle decreased gradually with the increasing of discharge power. The FTIR analysis results showed that the polar groups such as hydroxyl, carbonyl and carboxyl were formed on the surface of the composites treated under plasma. SEM and AFM results showed that the roughness of plasma treated samples increased. XPS analysis results indicated that the content of carbon element decreased while the content of oxygen element in the composition of wood/PE composites surface element increased and it reached a balance in a higher power, meanwhile a lot of carboxyl groups were formed. The newly formed polar groups are benefit for the adhesion of composites. The shear bonding strength test showed that the adhesion properties of wood/PE composites improved effectively after plasma treatment.

Keywords: Wood/polyethylene composites; Plasma; Surface treatment; Surface properties; Adhesion

Morphology of ablation craters generated by ultra-short laser pulses in dentin surfaces: AFM and ESEM evaluation by A. Daskalova; S. Bashir; W. Husinsky (pp. 1119-1124).

In this study, the surface morphology and structure of dentin after ablation by ultra-short pulses were evaluated using environmental scanning electron microscopy (ESEM) and atomic force microscopy (AFM). The dentin specimens examined were irradiated by a chirped-pulse-amplification (CPA) Ti:sapphire laser (800nm) and the optimal conditions for producing various nanostructures were determined. Based on the ESEM results, it was possible to identify an energy density range as the ablation threshold for dentin. The laser-induced damage was characterized over the fluence range 1.3–2.1J/cm². The results demonstrate that by selecting suitable parameters one can obtain efficient dentin surface preparation without evidence of thermal damage, i.e., with minimized heat affected zones and reduced collateral damage, the latter being normally characterized by formation of microcracks, grain growth and recrystallization in the heat affected zones.

Keywords: Dentin; Laser ablation; Surface modification; ESEM; AFM

Structural and optical properties of the S-doped ZnO particles synthesized by hydrothermal method by Yuanping Sun; Tao He; Hongying Guo; Tao Zhang; Weitian Wang; Zhenhong Dai (pp. 1125-1128).

Sulfur-doped ZnO particles have been synthesized by hydrothermal method. The structural and optical properties were studied systematically by XRD, scanning electron microscopy (SEM), and photoluminescence. SEM results show that the particle is hexagonal and the average size decreases with increasing sulfur doping, which means a retardant effect of sulfur on the growth of S-doped ZnO. XRD results show that the lattice parameters increase with more sulfur, which means an effective sulfur doping and increasing strain. Optical characterization also shows that the effective sulfur doping will enhance the green emission and suppress the near bandgap emissions.

Keywords: ZnO; Hydrothermal method; Optical properties; Structural properties

Comparison of phase behavior between water soluble and insoluble surfactants at the air–water interface by Md. Mufazzal Hossain; Kenichi Iimura; Teiji Kato (pp. 1129-1133).

The surface phase behavior of 2-hydroxyethyl myristate (2-HEM) has been studied in Langmuir monolayers by measuring surface pressure ( π)–area ( A) isotherms with a film balance and observing monolayer morphology with a Brewster angle microscope (BAM). These results are compared with the phase behavior of 2-hydroxyethyl laurate (2-HEL) in Gibbs monolayers studied by measuring π–time ( t) curves and observing monolayer morphology. The π– A isotherms of 2-HEM show a first-order phase transition from a liquid expanded (LE) phase to a liquid condensed (LC) phase in the temperature range between 5 and 35°C whereas the π– t curves of 2-HEL represent a similar phase transition in the temperature range between 2 and 25°C. The critical surface pressure, π_c necessary for the phase transitions increases with increasing temperature in both the cases. The LC domains formed in 2-HEM show circular shapes, which are independent of the temperature. In contrast, the circular domains having stripe texture formed at lower temperatures show a shape transition to fingering domains with uniform brightness at 15°C. The amphiphile, 2-HEM having 13-carbon chain has higher line tension than 2-HEL that has 11-carbon chain as tail. Thus, for 2-HEM, this high line tension always dominates over other factors giving rise to circular domains at the all studied temperatures.

Keywords: Langmuir monolayers; Gibbs monolayers; Phase transition; Brewster angle microscopy; 2-Hydroxyethyl myristate; 2-Hydroxyethyl laurate

Optical properties of (nanometer MCM-41)–(malachite green) composite materials by Xiao-Dong Li; Qing-Zhou Zhai; Ming-Qiang Zou (pp. 1134-1140).

Nanosized materials loaded with organic dyes are of interest with respect to novel optical applications. The optical properties of malachite green (MG) in MCM-41 are considerably influenced by the limited nanoporous channels of nanometer MCM-41. Nanometer MCM-41 was synthesized by tetraethyl orthosilicate (TEOS) as the source of silica and cetyltrimethylammonium bromide (CTMAB) as the template. The liquid-phase grafting method has been employed for incorporation of the malachite green molecules into the channels of nanometer MCM-41. A comparative study has been carried out on the adsorption of the malachite green into modified MCM-41 and unmodified MCM-41. The modified MCM-41 was synthesized using a silylation reagent, trimethychlorosilane (TMSCl), which functionalized the surface of nanometer MCM-41 for proper host–guest interaction. The prepared (nanometer MCM-41)–MG samples have been studied by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, low-temperature nitrogen adsorption–desorption technique at 77K, Raman spectra and luminescence studies. In the prepared (nanometer MCM-41)–MG composite materials, the frameworks of the host molecular sieve were kept intact and the MG located inside the pores of MCM-41. Compared with the MG, it is found that the prepared composite materials perform a considerable luminescence. The excitation and emission spectra of MG in both modified MCM-41 and unmodified MCM-41 were examined to explore the structural effects on the optical properties of MG. The results of luminescence spectra indicated that the MG molecules existed in monomer form within MCM-41. However, the luminescent intensity of MG incorporated in the modified MCM-41 are higher than that of MG encapsulated in unmodified MCM-41, which may be due to the anchored methyl groups on the channels of the nanometer MCM-41 and the strong host–guest interactions. The steric effect from the pore size of the host materials is significant. Raman spectra firmly demonstrated the stable form obtained after the MG incorporation into the nanometer MCM-41. Therefore, nanometer MCM-41 appears to have a good potential for its use as a support for dyes and the (nanometer MCM-41)–MG composite materials may give a wide optical application.

Keywords: Methylated MCM-41; Malachite green; Host–guest nanocomposite material; Optical property

RETRACTED: Photovoltaic behavior and work function of zinc oxides as solar cells by Xun-qiong Tan; Zheng-qiu Wu; Wen Zhi (pp. 1141-1144).

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy).This article has been retracted at the request of the editors of this journal as the authors have plagiarized part of a paper that had already appeared in Physica B, 404 (2009) 21972201 doi:10.1016/j.physb.2009.04.026. In addition, the identical paper was submitted and published in Vacuum, 85 (2010) 131134, doi:10.1016/j.vacuum.2010.04.014.One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

Direct observation of surface and internal phase-separated structure of the active layer buried in organic photovoltaic cells by Ifu Narayama; Daisuke Baba; Atsushi Takahara; Keiji Tanaka (pp. 1145-1148).

A phase-separated structure of the active layer, of variable thickness, buried in organic thin film solar cells (OTSC) was directly observed by scanning force microscopy (SFM) with the aid of a surface and interface cutting analysis system (SAICAS). This deals with SFM observation to both the surface and the internal regions of the OTSCs, leading to discussion about the formation of the overlayer in the active layer.

Keywords: Scanning force microscopy (SFM); Surface and interface cutting analysis system (SAICAS); Surface segregation; Polymer blends

Sections

Personal tools

Applied Surface Science (v.257, #3)

Sections

Personal tools

Local resources

Applied Surface Science (v.257, #3)