Applied Surface Science (v.241, #3-4)

Subject Index (III-X).

Author Index (I-II).

Surface treatment for forming unit-cell steps on the (0 0 1) KTaO3 substrate surface by Hyung-jin Bae; J. Sigman; D.P. Norton; L.A. Boatner (271-278).
A method for the preparation of unit-cell-high steps on the (1 0 0) surface of KTaO3 has been developed. The effects of various surface treatments on the (1 0 0) KTaO3 surface, specifically the chemical etching and annealing characteristics, are discussed. Surface step formation was observed for KTaO3 single-crystals that were subjected to buffered HF etching followed by annealing in air. The resulting surface morphology of (0 0 1) KTaO3 was examined using atomic force microscopy (AFM). The role of etching time and annealing temperatures in determining the resulting step structure, roughness, and particulate formation on the KTaO3 surface is discussed.
Keywords: Perovskite; KTaO3; Epitaxy;

Study on surface modification of ultrafine inorganic antibacterial particles by Ji-hui He; Wen-shi Ma; Shao-zao Tan; Jian-qing Zhao (279-286).
In the paper, titanate and aluminate-coupling agents were used to the surface modification of ultrafine inorganic antibacterial particles (UIAP) by dry mixing and solution methods. Several characterization methods were carried out to qualitatively and quantitatively analyze the results of surface modification such as FT-IR, water-absorbability and viscosity methods. The modified UIAP was added into PP to prepare antibacterial composites. The SEM showed that the surface-modified UIAP was well dispersed in PP and the average particle size was lower than 0.5 μm. Solution method has better effect on the surface treatment of inorganic particles compared with dry mixing method. The mechanical properties of composites were tested, and the results approved that coupling agents could improve the mechanical properties of composites in a certain range. The experimental results indicated that the optimal content of titanate- and aluminate-coupling agents were 1.5 and 2.0–3.0 wt.%, respectively. Examination of antibaterial property proved that surface modification had no influence on antibacterial capability of UIAP; moreover, PP/UIAP composites have good antibacterial property and broad-spectrum antibacterial capability as well as UIAP.
Keywords: Antibacterial property; Ultrafine inorganic antibacterial particle; Surface modification; Coupling agent;

DC-conductivity in the p-sexiphenyl films deposited on glass substrate was investigated at temperatures between 10 and 300 K. The thickness of the films was changed between 0.2 and 2.5 μm. Molecular dynamics simulations as well as quantum chemical calculations have shown that there exist at least three different parts of films effectively contributing to the observed features of DC-conductivity: proper crystalline states, amorphous-like inter-grain regions and grain boundaries interfaces. Comparing the experimental data and theoretically calculated dependences we demonstrated that main contribution to the observed DC-conductivity properties give interfaces situated on the borders between polycrystalline grains and amorphous-like substrate, though the latter possess relatively low part of the total film volume. Comparison with the N-phenyls films possessing less number of aromatic rings indicates on a crucial role of aromatics in the observed structural and optical properties.
Keywords: p-Sexiphenyl films; DC-conductivity; N-phenyls films;

Structural characterization of nitrogen doped diamond-like carbon films deposited by arc ion plating by Y.S. Zou; Q.M. Wang; H. Du; G.H. Song; J.Q. Xiao; J. Gong; C. Sun; L.S. Wen (295-302).
Nitrogen doped diamond-like carbon films were deposited on Si (1 0 0) substrates by arc ion plating (AIP) technique under different N2 volume percentage in the gas mixture of Ar and N2. The deposited films were characterized by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Raman spectra indicate that the I D/I G ratio increases with increasing the N2 volume percentage. XPS analysis shows a strong influence of the N2 volume percentage on the N atom concentration and the chemical bonding states in the deposited films. Nitrogen content of the deposited films increased with the increasing of N2 volume percentage. The maximum N concentration and N/C atomic ratio are up to 12.7 at.% and 0.162 at the 90 vol.% N2, respectively. From decomposition of XPS C 1s peaks, it shows that the nitrogen doped diamond-like carbon films consist of amorphous carbon–carbon bonding (sp2C―C and sp3C―C), N atoms bonded to sp3-hybridized C atoms (sp3C―N) and N atoms bonded to sp2-hybridized C atoms (sp2C―N). The total content of sp3 bonding decreases with increasing N2 volume percentage. XPS N 1s spectra show that there exist the N―sp2C and N―sp3C bonding in the deposited nitrogen doped diamond-like carbon films. As the N2 volume percentage increases, the N―sp3C bonding content increases, but the N―sp2C bonding content decreases.
Keywords: Nitrogen doped diamond-like carbon; Arc ion plating; X-ray photoelectron spectroscopy; Microstructure; Bonding structure;

Influence of post-annealing treatment on the structure properties of ZnO films by Z.B. Fang; Z.J. Yan; Y.S. Tan; X.Q. Liu; Y.Y. Wang (303-308).
Highly oriented polycrystalline ZnO films were deposited on Si substrate by rf reactive sputtering technique. X-ray diffraction (XRD), atomic force microscope (AFM) and the refractive index were employed to analyze the influence of the post-annealing treatment on the structural properties of ZnO thin films. It has been found that the grain size of ZnO thin films increases with increasing the annealing temperature, the shift of the diffraction peak position from its normal powder value was observed. AFM analysis shows that the surface roughness of ZnO films is very low at temperature between 250 and 600 °C. The packing density investigation shows ZnO films can obtain high packing densities (above 0.973) in the annealing temperature rang from 450 to 600 °C.
Keywords: ZnO films; rf Reactive sputtering; Annealing; Microstructure;

Electron-beam modification of textile fabrics for hydrophilic finishing by Mervat S. Ibrahim; Kariman M.El Salmawi; Sayeda M. Ibrahim (309-320).
A study has been made to modify different textile fabrics such as cotton, cotton/polyester blend and nylon-6 fabrics by surface coating with a constant thickness layer of 25 μm of aqueous solution of polyvinyl alcohol (PVA) and acrylic acid (AAc). Radiation curing of surface coating was accomplished by electron beam irradiation with a constant dose of 50 kGy. Parameters affecting hydrophilicity of cured coated fabrics, namely, presence or absence of cross-linking agent and concentration of AAc in coating solution, were investigated. Properties affiliated with hydrophilicity, specifically water uptake and weight loss, before and after several washing cycles were followed up. Crease recovery angle was determined. Considerable enhancement, in water uptake as well as crease recovery angle, has been attained with increasing AAc content in solution in case of nylon-6, followed by blends and then cotton. Moreover, dyeing properties for coated fabrics, with solution containing 4 wt.% AAc, has been tested by color difference method, for basic and reactive dyes. Relative increase in color strength has been achieved. The presence of cross-linking agent in coating solution played a significant role, specifically in case of dyeing properties. Morphology of coated fabrics was examined by scanning electron microscope (SEM), which indicated fastness and compatibility between coating and fabrics. Correlation between structure and obtained results was given.
Keywords: Polyvinyl alcohol; Acrylic acid; Hydrophilicity; Electron beam;

Dry etching of surface textured zinc oxide using a remote argon–hydrogen plasma by R. Groenen; M. Creatore; M.C.M. van de Sanden (321-325).
A new method for fast dry etching of inherently textured ZnO using a remote argon–hydrogen plasma created by a cascaded arc is presented, obtaining etch rates over 10 nm/s. Atomic hydrogen is considered to be the reactive species responsible for the etching process, the excess of molecular hydrogen in the gas phase does not contribute to the etching. Furthermore, using in situ spectroscopic ellipsometry (sub-) surface film modification competitive to etching is observed.
Keywords: Zinc oxide; Surface modification; Remote plasma;

Inhibitive action of two bipyrazolic isomers towards corrosion of steel in 1 M HCl solution by K. Tebbji; H. Oudda; B. Hammouti; M. Benkaddour; M. El kodadi; F. Malek; A. Ramdani (326-334).
The inhibitive action of two isomers of bipyrazolic type, namely, 4-{bis[(1,5-dimethyl-1H-pyrazolyl-3-yl)methyl]amino}phenol (isomer 1 ) and 4-{bis[(3,5-dimethyl-1H-pyrazolyl-1-yl)methyl]-amino}phenol (isomer 2 ), against the corrosion of steel in 1 M hydrochloric acid solution has been investigated at 308 K using weight loss measurements, polarisation and impedance spectroscopy methods. The inhibition efficiencies evaluated from the methods used are in good agreement. The polarisation curves reveal that these bipyrazolic compounds act as mixed-type inhibitors. These studies show that these compounds are efficient inhibitors. Inhibition efficiencies reach about 95% for isomer 1 and 2 at 5 × 10−4  M. The temperature effect on the corrosion behaviour of steel in 1 M HCl with and without the bipyrazolic compounds is studied in the temperature range from 308 to 353 K at 5 × 10−4  M. The activation energy for steel corrosion is determined. The isomers adsorb on the steel surface according to a Temkin isotherm adsorption model.
Keywords: Bipyrazole; Corrosion; Inhibition; Steel; Hydrochloric acid;

The influence of surface treatments on cathode formation and stability in polymer light emitting diodes by F.J.J. Janssen; A.W. Denier van der Gon; L.J. van IJzendoorn; R. Thoelen; M.J.A. de Voigt; H.H. Brongersma (335-351).
We studied the stability of metal/polymer interfaces by measuring the diffusion of calcium into a polymer (OC1C10 PPV) layer during and after deposition of the metal using low energy ion scattering (LEIS) and X-ray photoelectron spectroscopy (XPS).During deposition the calcium diffusion depth in the PPV was found to be comparable for untreated samples and samples prepared in oxygen ambient (10−7  mbar). In both cases diffusion depths up to ∼7 nm were observed. For PPV layers treated with atomic oxygen, the diffusion depth during deposition was slightly smaller.After deposition, it was observed that calcium diffusion in OC1C10 PPV continues for several hours. When oxygen was present during calcium deposition or during the spin coating of the PPV, the diffusion coefficient for calcium in PPV was decreased considerably. In these cases accumulation of oxygen (adsorbed in the PPV during deposition or spin coating) at the calcium/PPV interface continued for several hours after deposition. Treatment of the PPV with atomic oxygen before calcium deposition resulted in a strong decrease of the calcium diffusion coefficient after deposition.From XPS measurements it was observed that calcium interacts with the chemically bonded oxygen in the PPV and also with the oxygen absorbed in the PPV layer. It can be concluded that oxygen, either chemically bonded to the PPV chain or adsorbed in the film, reduces the calcium diffusion coefficient.The initial performance of PLEDs with atomic oxygen treated PPV layers and PLEDs with calcium deposited in oxygen ambient was worse than the performance of untreated devices, but the stability in the life-test was better.
Keywords: Conjugated polymers; Light emitting diodes; Surface treatment; Stability; Low energy ion scattering;

RETRACTED: Passivation properties of OLEDs with aluminum cathodes prepared by ion-beam-assisted deposition process by Soon Moon Jeong; Won Hoi Koo; Sang Hun Choi; Sung Jin Jo; Hong Koo Baik; Seong Min Lee (352-361).
Reason: This Applied Surface Science submission contained essentially identical data, graphs, analysis, and conclusions of other articles that the authors had submitted and published concurrently in several other journals without notifying Applied Surface Science or the other journals involved. This is a clear violation of the Applied Surface Science policy: “Submission of a manuscript implies it is not being simultaneously considered for publication elsewhere and that the authors have obtained the necessary authority for publication.”The authors have therefore been asked to submit a formal letter of retraction, which has been received by the editorial office of Applied Surface Science. In this letter the corresponding author, Prof. Hong Koo Baik, apologized for the duplicate publication and acknowledges his responsibility for this incident.

Absorption is an essential mechanism during laser materials processing, affecting the process efficiency and reliability, but is studied little due to its complex nature. A mathematical model was developed to calculate the absorptivity and the resulting temperature field as a function of space and time during pulsed laser heating of a plane surface, based on modelling the temperature dependence of the absorptivity, here for Au/Ni-galvanized Cu-substrate as an electronic material. For this extremely reflecting case, the absorptivity can increase by a factor of seven during the process. Beside sensitivity analysis of process parameter variations, a process theory can be stated for a variety of effects like the absorption dependence on surface pollutions, diffusion of the coating during melting, acceleration of heating during melting, saturation when the melt exceeds the beam size and onset of evaporation, etc.
Keywords: Absorption; Absorptivity; Modelling; Laser; Heating; Welding;

Atomic force measurements of 16-mercaptohexadecanoic acid and its salt with CH3, OH, and CONHCH3 functionalized self-assembled monolayers by Angel L. Morales-Cruz; Rolando Tremont; Ramón Martínez; Rodolfo Romañach; Carlos R. Cabrera (371-383).
Chemical and mechanical properties of different compounds can be elucidated by measuring fundamental forces such as adhesion, attraction and repulsion, between modified surfaces by means of atomic force microscopy (AFM) in force mode calibration. This work presents a combination of AFM, self-assembled monolayers (SAMs), and crystallization techniques to study the forces of interaction between excipients and active ingredients used in pharmaceutical formulations.SAMs of 16-mercaptohexadecanoate, which represent magnesium stereate, were used to modify the probe tip, whereas CH3-, OH- and CONHCH3-functional SAMs were formed on a gold-coated mica substrate, and used as examples of the surfaces of lactose and theophylline. The crystals of lactose and theophylline were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The modification of gold surfaces with 16-mercaptohexadecanoate, 10-mercapto-1-decanol (OH-functional SAM), 1-decanethiol (CH3-functional) and N-methyl-11-mercaptoundecanamide (CONHCH3-functional SAM) was studied by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and Fourier transform-infrared spectroscopy (FT-IR) in specular reflectance mode. XPS and AES results of the modified surfaces showed the presence of sulfur binding, and kinetic energies that correspond to the presence of 10-mercapto-1-decanol, 1-decanethiol, N-methyl-11-mercaptoundecanamide and the salt of 16-mercaptohexadecanoic acid. The absorption bands in the IR spectra further confirm the modification of the gold-coated substrates with these compounds. Force versus distance measurements were performed between the modified tip and the modified gold-coated mica substrates. The mean adhesion forces between the COOCa2+ functionalized tip and the CH3-, OH-, and CONHCH3-modified substrates were determined to be 4.5, 8.9 and 6.3 nN, respectively. The magnitude of the adhesion force (ion–dipole) interaction between the modified tip and substrate decreases in the following order: COOCa2+/OH > COOCa2+/CONHCH3 > COOCa2+/CH3.

Nanocrystalline ZnO thin films on porous silicon/silicon substrates obtained by sol–gel technique by Chen Shaoqiang; Zhang Jian; Feng Xiao; Wang Xiaohua; Luo laiqiang; Shi Yanling; Xue Qingsong; Wang Chang; Zhu Jianzhong; Zhu Ziqiang (384-391).
In this study, nanocrystalline ZnO thin films deposited onto silicon substrates by sol–gel technique were studied. The starting material for ZnO sol–gel thin films was Zinc acetate. Single crystalline silicon wafers with different orientations and the porous silicon substrates were used as the substrates. XRD was employed to investigate the evolution of the crystalline orientation during the thermal treatment, and SEM was used to observe the surface morphology of the ZnO films. The effects of the anneal temperature and the substrate doping type on the deposited ZnO thin films were studied in detail. The results indicated that the highly oriented ZnO could be generated on Si substrates by controlling the process conditions. It was found that the substrates types had less influence on the obtained ZnO thin films compared with the anneal temperatures. Thin porous silicon substrates introduced is beneficial to enhance the bonding strength between the films and the substrates. These results are helpful to deposit the highly orientation-controlled ZnO thin films for different kinds of research and application.
Keywords: ZnO films; Porous silicon; Sol–gel; Orientation; Anneal temperature;

Effect of pre-treatment and nickel layer thickness on nickel silicide/silicon carbide contact by Yu Cao; Lars Nyborg; Urban Jelvestam; Danqing Yi (392-402).
This investigation deals with the impact of pre-treatment and Ni thickness on the reactions of Ni–silicide/SiC contact fabrication. The specimens have been prepared by sputter depositing 3–100 nm Ni layer on 4H–SiC wafer followed by annealing at 800 °C in vacuum for 20 min. The results by means of XPS show as follows: among the chemical cleaning procedures which have been tested, the recipe NH4OH:H2O2:H2O = 1:1:5, 85 °C, 5 min; HF 10%, 80 °C, 2 min; boiling water 10 min is the most effective for SiC substrates. However, due to short time exposure in the air before experiment, certain contamination re-occurs. After annealing, the dominant silicide formed is Ni2Si, whereas C on the surface is graphite. Argon ion etching before the Ni deposition helps the formation of multi-layer structure. For the samples without pre-treatment or with chemical cleaning procedure, there is more C agglomerated at the surface and no multi-layer structure formed. Under the action of Ar ion etching, SiC decomposes more quickly and Ni diffuses faster. This effect together with limited C diffusivity in the formed silicide is a probable reason for the formation of the multi-layer structure. The silicides formed at the interface are dependent on the Ni layer thickness and substrate surface condition.
Keywords: Silicon carbide; Metal contact; Interfacial reaction; XPS; Depth profile;

Epitaxy relationships between Ge-islands and SiC(0 0 0 1) by K. Aït-Mansour; D. Dentel; L. Kubler; M. Diani; J.L. Bischoff; D. Bolmont (403-411).
Reflection high-energy electron diffraction (RHEED) has been used to determine epitaxy relationships and in-plane orientations between Ge and SiC(0 0 0 1). Three monolayers of Ge have been deposited at 500 °C on a graphitized SiC (6√3 × 6√3)R30° reconstructed surface, this surface supporting epitaxial Ge island growth in a Volmer–Weber mode. Nucleation of relaxed Ge-islands gives rise to transmission electron diffraction patterns allowing to deduce that pure Ge grows according to only one epitaxy relationship Ge{1 1 1}//SiC(0 0 0 1). These {1 1 1}-Ge-islands have two in-plane orientations, a preferential one, Ge〈-1-12〉//SiC〈1-100〉 and a minority one, Ge〈-1-12〉//SiC〈10-10〉, deduced one from the other by a 30° rotation around the 〈1 1 1〉-Ge (or [0 0 0 1]-SiC) growth axis. Due to the three-fold symmetry of the {1 1 1}-Ge plane, each in-plane orientation is degenerated into two twin orientations, differing by a 180° angle around Ge〈111〉.
Keywords: Reflection high-energy electron diffraction (RHEED); Epitaxy relationships; In-plane orientations; Germanium (Ge) islands; Silicon carbide (SiC); C-rich reconstructed surface;

Fabrication of α-AlO(OH)·SiO2 with core-shell structures by heterogeneous nucleation-and-growth processing by Yue Feng Tang; Zhi Peng Huang; Liang Feng; Yan Feng Chen (412-415).
Multicomponents mixture in the procedure of ceramic preparation is an important procedure, but it is difficult as multicomponents are mixed homogeneously in the traditional process. In order to solve this difficult problem, a novel processing (heterogeneous nucleation-and-growth processing) was used to prepare homogeneous distribution powders. Composite coating particles with mullite stoichiometric ratio (consisting of alpha monohydrate bauxite (α-AlO(OH)) cores without aggregation (average particle size 1.23 μm) with an outer homogeneous amorphous silica layer) were prepared by heterogeneous nucleation-and-growth processing. Effects of silica content in composite coating particles versus concentration of tetraethylorthosilicate, pH value, reaction time and reaction temperature were studied. A homogeneous amorphous silica layer on α-AlO(OH) cores was confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and zeta-potentials.
Keywords: Composite coating particles; Heterogeneous nucleation-and-growth processing; Core-shell structures; Homogeneous shell; Mullite stoichiometric ratio; Zeta-potentials;

Formation of array microstructures on silicon by multibeam interfered femtosecond laser pulses by Quan-Zhong Zhao; Jian-Rong Qiu; Chong-Jun Zhao; Xiong-Wei Jiang; Cong-Shan Zhu (416-419).
We report on an optical interference method to fabricate array microstructures on the surface of silicon wafers by means of five-beam interference of femtosecond laser pulses. Optical microscope and scanning electron microscope observations revealed microstructures with micrometer-order were fabricated. The diffraction characteristics of the fabricated structures were evaluated. The present technique allows one-step realization of functional optoelectronic devices on silicon surface.
Keywords: Array microstructure; Interference; Femtosecond laser; Diffractive beam splitter; Silicon;

Pigment colors printing on cotton fabrics by surface coating induced by electron beam and thermal curing by Abdel Wahab M. El-Naggar; Maged H. Zohdy; Hossam M. Said; Mahmoud S. El-Din; Dalia M. Noval (420-430).
Cotton fabrics were coated from one surface with different pigment colors incorporated in formulations containing ethylene glycol (EG), methyl methacrylate (MMA) and poly(methyl methacrylate) (PMMA) oligomer as a base material. The coated fabrics were exposed to various doses of accelerated electrons generated from the 1.5 MeV (25 kW) electron beam accelerator machine. In order to find the suitable conditions that afford the highest performance of pigment printing, the effect of irradiation dose and formulation composition on the color strength of the printed fabrics was investigated. The durability of the printed fabrics in terms of color fastness, tensile mechanical, crease resistance and water absorption was also studied. The results of pigment printing by electron beam irradiation was compared with the conventional thermal printing method with the same pigment colors involving the use of pastes containing binder and thickener systems. It was found that cotton fabrics printed with the pigment colors under the effect of electron beam irradiation displayed higher color strength than those fabrics printed by the conventional thermal fixation at equal pigment color ratios. In this regard, the color strength on cotton fabrics printed with the Imperon violet, blue and yellow pigment colors was 85.2, 75.4 and 91.3 in the case of printing with electron beam and 63.5, 46.0 and 50.2 in the case of thermal curing, respectively. The results showed that the pigment printing by electron beam or thermal curing improves the crease recovery and mechanical properties of cotton fabrics and exhibited comparable durability properties in terms of washing, rubbing and handling.
Keywords: Pigment; Printing; Cotton; Electron beam; Thermal;

A method of microtip fabrication based on oxygen induced faceting by Robert Bryl; Andrzej Szczepkowicz (431-434).
The macroscopic W[1 1 1] tip facets and forms a truncated three-sided pyramid when annealed at 1400–1600 K after being exposed to about 1.3 Langmuir of oxygen. Further annealing of the tip in temperature range of 1000–1060 K leads to significant sharpening of the tip apex. FIM observations revealed that the apex consisted of several atoms at most. FEM images of such prepared tips suggest that they can be used as point sources of electrons.
Keywords: Microtips; Ultrasharp field emitters; Faceting; Oxygen; Tungsten; Field ion microscopy; Field emission microscopy;

The nanocrystalline ZnS films are successfully produced by sulfidation of the as-deposited ZnO films of various sputtering time in the H2S–H2–N2 mixture. At the deposition time ≤ 30 min, after 2 h sulfidation at 500 °C, the as-deposited ZnO films can be converted totally to the hexagonal ZnS films with a strongly (0 0 2) preferred orientation. However, the ZnS films converted from the 10-min deposited ZnO films have a poor crystallinity because of the great influence of the substrates on the properties of the films with the very small thickness. The good crystallinity, the high optical transparency of about 80% in the visible region and the band-gap energy of 3.68 eV are obtained for the ZnS films formed by sulfurizing the 30-min deposited ZnO films. In addition, it is found that the ZnS films produced by sulfurizing the as-deposited ZnO films almost have the same good crystallinity as those prepared by sulfurizing the annealed ZnO films, a reason for which is due to the strongly (0 0 2) preferred orientation during the growth of the ZnS films. This indicates that the ZnS films formed by sulfidation of the as-deposited ZnO films are suitable for use in the thin film solar cells.
Keywords: ZnS; Sulfidation; ZnO; Solar cells;

Laser-induced damage morphology of high-reflective optical coatings by Hong-Bo He; Hai-Yang Hu; Zhi-Ping Tang; Zheng-Xiu Fan; Jian-Da Shao (442-448).
Two different kinds of 1064 nm high-reflective (HR) coatings, with and without SiO2 protective layer, were prepared by electron beam evaporation. Three-dimensional damage morphology, caused by a Nd:YAG pulsed laser, was investigated for these HR coatings. Development of laser-induced damage on HR coatings was revealed by both temperature field calculation and discrete meso-element simulation. Theoretical results met experimental very well.
Keywords: High-reflective coating; Laser-induced damage threshold; Temperature field; Discrete meso-element method;

The electrochemical behaviour of brass was studied in artificial seawater with two organic inhibitors namely N,N-dibenzotriazol-1-ylmethylaminomethane (DBMM) and 3-hydroxypropyl benzotriazole (HPBT) using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), cyclic voltammetry and current transient techniques. Preliminary screening of the inhibition efficiency (IE) was carried out using weight-loss measurements. Polarization measurements showed that the organic compounds investigated are mixed type inhibitors, inhibiting the corrosion of brass by blocking the active sites of the metal surface. Changes in the impedance parameters (charge transfer resistance (R ct) and double layer capacitance (C dl)) are related to adsorption of organic inhibitors on the metal surface, leading to the formation of a protective film, which grows with increasing exposure time. Cyclic voltammetric studies confirmed that the addition of inhibitors effectively inhibits the anodic dissolution of brass in artificial seawater.
Keywords: Corrosion inhibitors; Cyclic voltammetry; Impedance; Polarization; Seawater;

A study of the anodic oxidation of nickel-based alloys in molten NaOH is presented, investigating the mechanism of growth, the composition and structure of the surface oxide films. The potential ranges of passivation, passivity and transpassivity have been estimated by voltammetry. Impedance measurements were performed in the passive potential region to investigate the conductivity mechanism of the oxide films. The surface and in-depth composition of the films has been estimated by X-ray photoelectron spectroscopy and Auger electron spectroscopy. As a result, the main passivation product on the Ni surface was found to be NiO. Further oxidation of the NiO layer was presumed to lead to the formation of Ni(III) ions and nickel cation vacancies. Transport of nickel cation vacancies was assumed to be the rate-limiting step of the overall process in the passive region. A tentative kinetic model of the nickel alloy/oxide/melt system is proposed to describe the impedance spectra. On the basis of the model, several kinetic and transport parameters are estimated.
Keywords: Nickel-based alloy; Molten hydroxide; Anodic oxide film; Electrochemical impedance spectroscopy; Point defect transport;

Selective electroless deposition of copper on polyimide surface by microcontact printing by Yi Li; Dongsheng Chen; Qinghua Lu; Xuefeng Qian; Zikang Zhu; Jie Yin (471-476).
Polyimide can hardly be patterned by microcontact printing method due to its poor adhesive property. This paper reports the electroless deposition of copper pattern on a siloxane-containing polyimide by microcontact printing. The incorporation of siloxane components into polyimide changes the surface properties of polyimide and enables it to be directly patterned by elastic stamp transferred organic silane. Selectively copper deposition is achieved through the silane patterns, which define the catalysts bound area. The siloxane-containing polyimide is demonstrated to be a suitable substrate for microcontact printing which does not need to be chemically modified prior to stamping. The simplicity of this process for creating selective copper patterns on polyimide material is highlighted.
Keywords: Polyimide; Microcontact printing; Organic silane; Electroless deposition;

Corrosion inhibition effect of tetramines for mild steel in 1M HCl by S. Sathiyanarayanan; C. Marikkannu; N. Palaniswamy (477-484).
In this investigation, attempts have been made to study the inhibitive effect of triethylene tetramine (TETA) and hexamethylene tetramine (HMTA) for mild steel in 1 M hydrochloric acid in the concentration range of 10−6 to 10−2  M by weight loss, DC polarization methods and AC impedance spectroscopy. Results indicate that the addition of tetramines to the acid reduce the rate of metal attack. For both the amines, inhibition efficiency increases with the concentration of amine. The inhibition efficiency of the hexamethylene tetramine is less when compared to that of triethylene tetramine.
Keywords: Corrosion inhibition; Mild steel; Acid;

Vascular grafts made of expanded polytetrafluoroethylene (ePTFE) are widely employed in vascular reconstructive surgery. While they are successful as replacements for large-diameter blood vessels, ePTFE vascular grafts are unsuitable for small-diameter ones because when the internal diameters of the graft are less than 6 mm, they are found to fail without exception due to blood clot formation. To reduce platelets adhesion onto the ePTFE vascular graft, a novel method of binding of chitosan/heparin (CS/Hp) complex to the surface of vascular graft was developed. The binding of chitosan was achieved by irradiating with ultraviolet light the azide modified chitosan that was coated on the ePTFE surface. By forming complex with this coating of chitosan, heparin was then bonded to the ePTFE surface. In vitro blood compatibility experiments showed that CS/Hp surface-modified ePTFE vascular grafts exhibited markedly reduced platelets adhesion. The outstanding performance of these grafts was further demonstrated by the in vivo experiments, in which they were found to be still unclogged two weeks post-implantation into dog veins.
Keywords: Chitosan/heparin complex; UV photosensitive; ePTFE vascular graft; Blood-compatibility;

Growth of ZnS films by chemical vapor deposition of Zn[S2CN(CH3)2]2 precursor by Everett Y.M. Lee; Nguyen H. Tran; Robert N. Lamb (493-496).
Crystalline ZnS films have been grown on a variety of substrates using chemical vapor deposition from zinc dimethyl dithiocarbamate Zn[S2CN(CH3)2]2 as a single source precursor. Transmission electron microscopy and X-ray diffraction indicated that the films were composed of a uniform array of columns with cubic [1 1 1] orientation. Depth profile X-ray photoemission spectroscopy indicated that the impurity concentration remained less than 1 atomic percent (at%) in the bulk of the films. Chemical vapor deposition of zinc dimethyl dithiocarbamate offers advantages over previous precursors to improve significantly the physico-chemical properties of ZnS films.
Keywords: Dimethyl dithiocarbamate; Single source chemical vapor deposition; Zinc sulfide;