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Applied Surface Science (v.252, #24)

Microstructure of epitaxial scandium nitride films grown on silicon by M.A. Moram; T.B. Joyce; P.R. Chalker; Z.H. Barber; C.J. Humphreys (pp. 8385-8387).

Epitaxial scandium nitride films (225nm thick) were grown on (111)-oriented silicon substrates by molecular beam epitaxy (MBE), using ammonia as a reactive nitrogen source. Film microstructure was investigated using X-ray diffraction (XRD). The (111) ω-scan FWHM of 0.551° obtained for films grown at 850°C is the lowest reported so far for ScN thin films. The principal orientation of ScN with respect to Si is (111)_ScN//(111)_Si and [11¯0]_ScN//[01¯1]_Si, representing a 60° in-plane rotation of the ScN layer with respect to the Si substrate. However, some twinning is also present in the films; the orientation of the twinned component is (111)_ScN//(111)_Si and [11¯0]_ScN//[11¯0]_Si, representing a ‘cube-on-cube’ orientation. The volume percentage of these twins in the films decreases with increasing film growth temperature.

Keywords: PACS; 68.55.Jk; 61.10.Nz; 81.15.HiScandium nitride; Thin film; Microstructure; Silicon; X-ray diffraction; Molecular beam epitaxy

Study of the interface formed between poly(2-methoxy-5-(2′-ethyl-hexyloxyl)- p-phenylene vinylene) and indium tin oxide in top emission organic light emitting diodes by T.P. Nguyen; J. Ip; C. Renaud; C.H. Huang; C. Guillen; J. Herrero (pp. 8388-8393).

X-ray photoelectron spectroscopy (XPS) technique have been used to investigate the interface formed between poly(2-methoxy-5-(2′-ethyl-hexyloxyl)- p-phenylene vinylene) (MEH-PPV) and indium tin oxide (ITO) layer in top emission organic light emitting diodes. A weak but noticeable diffusion of indium into the polymer film was observed. Interactions between the diffused metallic atoms with the polymer resulted in the formation of carbon–metal complexes at the interface region. Compared to the ITO/MEH-PPV interface, the penetration of indium into the polymer layer was less important and may be explained by the surface morphology of the polymer film. It was however, a probable factor for fast degradation of devices using this structure.

Keywords: PACS; 68.35 Fx; 68.47 Mn; 79.60 FrPolymer–ITO interface; Chemical interaction; TOLEDs; X-ray photoelectron spectroscopy; Diffusion

The coexistence of γ(γ′) and θ alumina observed by STM and LEED on top of oxide layer grown on CoAl(100) by V. Podgursky; V. Rose; J. Costina; R. Franchy (pp. 8394-8398).

We report the coexistence of γ(γ′) and θ alumina grown on the CoAl(100) surface. Both phases were observed after annealing of alumina at 1150K by means of scanning tunnelling microscopy (STM). The crystal structures of γ(γ′) and θ alumina were indexed based on low energy electron diffraction (LEED) and STM experimental data.

Keywords: Oxidation; Alumina; Phase transition; STM; LEED

IR study on the effect of chloride ion on porous silicon by K. Sreejith; C.G.S. Pillai (pp. 8399-8403).

Infrared (IR) studies have been carried out on porous silicon samples to infer on the changes in the surface bonding in the porous silicon (PS) layer due to chloride (Cl⁻) and subsequent fluoride (F⁻) ion exposures with respect to time. It is observed that silicon hydride linkages decreases and silicon oxide linkages increases with time of exposure to HCl, suggesting a possible oxidation of the porous layer. IR study revealed the formation of SiO (silanones) bonds. A possible mechanism for the formation of silanones from SiOH species has been proposed to explain the observation. We also observed a saturation of silicon oxide groups with complete disappearance of silicon hydride peaks indicating the complete conversion of silicon hydride to oxides. Furthermore on exposure to F⁻, the IR spectrum showed a rapid destruction of silicon oxygen linkages.

Keywords: Porous silicon; Infrared spectroscopy; Silanone

Effects of Si doping on the structural and electrical properties of Ge₂Sb₂Te₅ films for phase change random access memory by Baowei Qiao; Jie Feng; Yunfeng Lai; Yun Ling; Yinyin Lin; Ting’ao Tang; Bingchu Cai; Bomy Chen (pp. 8404-8409).

The effects of Si doping on the structural and electrical properties of Ge₂Sb₂Te₅ film are studied in detail. Electrical properties and thermal stability can be improved by doping small amount of Si in the Ge₂Sb₂Te₅ film. The addition of Si in the Ge₂Sb₂Te₅ film results in the increase of both crystallization temperature and phase-transition temperature from face-centered cubic (fcc) phase to hexagonal (hex) phase, however, decreases the melting point slightly. The crystallization activation energy reaches a maximum at 4.1at.% and then decreases with increasing dopant concentration. The electrical conduction activation energy increases with the dopant concentration, which may be attributed to the increase of strong covalent bonds in the film. The resistivity of Ge₂Sb₂Te₅ film shows a significant increase with Si doping. When doping 11.8at.% of Si in the film, the resistivity after 460°C annealing increases from 1 to 11mΩcm compared to the undoped Ge₂Sb₂Te₅ film. Current–voltage ( I– V) characteristics show Si doping may increase the dynamic resistance, which is helpful to writing current reduction of phase-change random access memory.

Keywords: PACS; 61.43.Dq; 68.55.In; 81.30.Hd; 84.37.+qSi doping; Ge; ₂; Sb; ₂; Te; ₅; Activation energy; Resistivity; Dynamic resistance; Phase-change memory

ZnO nanostructures with different morphologies and their field emission properties by Hongmei Hu; Ke Yu; Jianzhong Zhu; Ziqiang Zhu (pp. 8410-8413).

Zinc oxide (ZnO) products with the morphologies of balls, nunchakus and belts have been synthesized from aqueous solutions by adjusting the reagent concentration and reaction time. The X-ray diffraction (XRD) peaks of the products were indexed to ZnO materials, but exhibited different relative intensities for the (002) diffraction peak. Field emission (FE) measurements showed that the turn-on and threshold field for the ZnO nanonunchakus were 3.01±0.005 and 5.47±0.005, 3.71±0.005 and 6.43±0.005V/μm, respectively, for the ZnO nanobelts, revealing that the products have comparable FE properties with those of the reported ZnO nanowires and carbon nanotubes (CNTs).

Keywords: PACS; 81.05.Dz; 81.10.Dn; 85.45.DbZnO nanostructures; Growth from solutions; Field emission

Comparison of growth stress measurements with modelling in thin iron oxide films by B. Panicaud; J.L. Grosseau-Poussard; P. Girault; J.F. Dinhut; D. Thiaudière (pp. 8414-8420).

High temperature oxidation of metals leads to residual stresses both in the metal and in the growing oxide. In this work, the evolution of this residual stresses is theoretically predicted in the growing oxide layers. The origin of these stresses is based on a microstructural model. Using experimental results providing from the oxidation kinetics, and an analysis proposed to describe the growth strain occurring in the thin layers, a set of equations is established allowing determining the stresses evolution with oxidation time. Then, the model is compared with experimental results obtained on both α-Fe and phosphated α-Fe, oxidised at different temperatures. Numerical data are extracted from experiments either with an asymptotic formulation or with an inverse method. These two methods give good agreement with experiments and allow extracting the model parameters.

Keywords: High temperature oxidation; Iron oxidation; Growth strain; Residual stresses; Modelling; Asymptotic solution; Numerical approach; Inverse method

The study on the surface state of CdZnTe (110) surface by Gangqiang Zha; Wanqi Jie; Qiang Li; Dongmei Zeng; Ge Yang; Xuxu Bai; Tao Wang; Wenhua Zhang; Faqiang Xu (pp. 8421-8423).

Angle-resolved photoemission spectroscopy (ARPES) was used to characterize the surface state of clean CdZnTe (110) surface. The surface state of CdZnTe with the peak at 0.9eV below the Fermi level is identified. Meanwhile, Photoluminescence (PL) spectrum confirmed that there existed a surface trap state which introduced a deep-level peak at 1.510eV. The surface trap states can be decreased by aging in dry-air. The surface leakage current was measured also by I– V measurements. After aging, the leakage current was decreased remarkably, which suggested that the aging treatment is an effective method to decrease the surface trap state.

Keywords: CdZnTe crystal; Surface state; Aging; ARPES; PL; I; –; V; measurement

Photoluminescence from C⁺ ion-implanted and electrochemical etched Si layers by Liwei Shi; Qiang Wang; Yuguo Li; Chengshan Xue; Huizhao Zhuang (pp. 8424-8427).

The microstructural and optical analysis of Si layers emitting blue luminescence at about 431nm is reported. These structures have been synthesized by C⁺ ion implantation and high-temperature annealing in hydrogen atmosphere and electrochemical etching sequentially. With the increasing etching time, the intensity of the blue peak increases at first, decreases then and is substituted by a new red peak at 716nm at last, which shows characteristics of the emission of porous silicon. CO compounds are induced during C⁺ implantation and nanometer silicon with embedded structure is formed during annealing, which contributes to the blue emission. The possible mechanism of photoluminescence is presented.

Keywords: PACS; 78.55.−m; 81.65.Cf; 85.40.RyIon implantation; Annealing; Chemical etching; Photoluminescence

Laser short pulse heating: Influence of pulse intensity on temperature and stress fields by B.S. Yilbas; A.F.M. Arif (pp. 8428-8437).

Laser short-pulse heating of gold surface is considered and the influence of laser pulse intensity on the temperature and stress fields is investigated. Laser step input pulses with different pulse lengths and the same energy content are employed in the simulations. The electron kinetic theory approach employing thermomechanical coupling is introduced to model the non-equilibrium energy transport in the electron and lattice sub-systems. Thermal stress development in the lattice sub-system and temperature rise in the lattice and electron sub-systems are computed. It is found that electron temperature rises rapidly while lattice site temperature rise is gradual in the early heating period, which is more pronounced for high intensity pulses. Thermal stress component in the axial direction is compressive and its magnitude is considerably less than the yielding limit of the substrate material.

Keywords: Laser; Short-pulse; Heating; Elastic; Stress

Optical properties of In₂O₃ oxidized from InN deposited by reactive magnetron sputtering by Lung-Chien Chen; Wen-How Lan; Ray-Ming Lin; Hue-Tang Shen; Hung-Chang Chen (pp. 8438-8441).

Unintentionally doped and zinc-doped indium nitride (U-InN and InN:Zn) films were deposited on (0001) sapphire substrates by radio-frequency reactive magnetron sputtering, and all samples were then treated by annealing to form In₂O₃ films. U-InN and InN:Zn films have similar photon absorption characteristics. The as-deposited U-InN and InN:Zn film show the absorption edge, ∼1.8–1.9eV. After the annealing process at 500°C for 20min, the absorption coefficient at the visible range apparently decreases, and the absorption edge is about 3.5eV. Two emission peaks at 3.342eV (371nm) and 3.238eV (383nm) in the 20K photoluminescence (PL) spectrum of In₂O₃:Zn films were identified as the free-exciton (FE) or the near band-to-band (B–B) and conduction-band-to-acceptor (C–A) recombination, respectively.

Keywords: InN; Reactive magnetron sputtering; In; ₂; O; ₃; Photoluminescence

Modification of a three-way catalyst washcoat by aging: A study along the longitudinal axis by M. López Granados; F. Cabello Galisteo; R. Mariscal; M. Alifanti; A. Gurbani; J.L.G. Fierro; R. Fernández-Ruíz (pp. 8442-8450).

This work reports the research carried out by studying aliquots extracted at different axial coordinates from Three Way Catalyst (TWC) monoliths aged under real traffic conditions. Our study focused on the catalytic properties and on several chemical and physical effects caused in the Front and Rear monolith washcoat surfaces by vehicle aging after 60,000km. Regarding the catalytic properties, all the used aliquots showed poorer activity than their corresponding fresh counterparts. The strongest deactivation was detected for NO and hydrocarbon conversion. CO conversion was less affected and the Rear monolith was as deactivated as the Front one. The characterisation techniques (TXRF, N₂ adsorption–desorption isotherms, XRD and H₂-TPR) detected – (i) the deposition of P, Zn and Pb; (ii) the formation of CePO₄ on account of the Ce from the washcoat; (iii) thermal sintering; (iv) inhibition of the reducibility of Ce oxides – as the main effects brought about by vehicle aging conditions. The deactivation observed at the beginning of the Front monolith was the result of a combination of the former effects. When moving downstream to higher axial coordinates, Pb accumulation and the loss of specific area appeared to be the only probable sources of deactivation.

Keywords: Vehicle-aged TWC deactivation; CePO; ₄; formation; Washcoat sintering; Pb poisoning

Structural and optical properties of ZnO thin films deposited on quartz glass by pulsed laser deposition by Lei Zhao; Jianshe Lian; Yuhua Liu; Qing Jiang (pp. 8451-8455).

ZnO thin films with typical c-axis (002) orientation were successfully deposited on quartz glass substrates by pulse laser ablation of Zn target in oxygen atmosphere at a relatively low temperature range of 100–250°C. The structural and optical properties of the films were studied. In photoluminescence (PL) spectra at room temperature, single ultraviolet emission (without deep-level emission) was obtained from ZnO film deposited at the temperature of 200°C. This was attributed to its low intrinsic defects.

Keywords: ZnO; Pulsed laser deposition; Ultraviolet photoluminescence

IR investigation of the interaction of deuterium with Ce_0.6Zr_0.4O₂ and Cl-doped Ce_0.6Zr_0.4O₂ by F.C. Gennari; T. Montini; N. Hickey; P. Fornasiero; M. Graziani (pp. 8456-8465).

The interaction of deuterium with Ce_0.6Zr_0.4O₂, synthesised by a co-precipitation technique, is discussed on the basis of the sample's bulk and surface composition and the presence of trace amounts of silicon. Redox cycling resulted in surface cerium enrichment, which, however, only moderately affected the interaction of the material with D₂. Addition of a trace amount of chloride ion to the oxide surface promoted both H/D scrambling and vacancy creation. Chloride ion was also found to prevent the surface cerium enrichment induced by redox cycling.

Keywords: Ceria–zirconia-based materials; Ceria reduction; Heterogeneous catalyst; Hydrogen activation; Deuterium scrambling

Surface reaction mechanism of atomic layer deposition of HfO₂ on Ge(100)-2×1: A density functional theory study by Jie Ren; Hong-Liang Lu; Wei Chen; Min Xu; David Wei Zhang (pp. 8466-8470).

Density functional theory is employed to investigate atomic layer deposition mechanism of HfO₂ on Ge(100)-2×1 surface. Both the HfCl₄ and H₂O half-reactions proceed through an analogous trapping-mediated mechanism. The neighboring hydroxyl in the reaction of HfCl₄ with two Ge–OH* sites has a major effect on the formation of HfCl₄ adsorbed complex. In addition, both the Ge and Si reaction pathways are qualitatively similar, however, adsorption of HfCl₄ is favorable on Ge than on Si surface hydroxyl sites. By comparison of the reactions of H₂O on the different surfaces, the differences in energy are negligible to alter the reaction mechanism.

Keywords: PACS; 31.15.E; 52.75.RAb initio calculation; Dielectrics; Atomic layer deposition; Chemisorption

The effect of microwave annealing on the electrical characteristics of lanthanum doped bismuth titanate films obtained by the polymeric precursor method by A.Z. Simões; M.A. Ramírez; B.D. Stojanovic; E. Longo; J.A. Varela (pp. 8471-8475).

Lanthanum doped bismuth titanate thin films (Bi_3.25La_0.75Ti₃O₁₂ – BLT) were produced by the polymeric precursor method and crystallized in a domestic microwave oven and in conventional furnace. Using platinum coated silicon substrates configuration, ferroelectric properties of the films were determined with remanent polarization P_r and a coercive field E_c of 3.9μC/cm² and 70kV/cm for the film annealed in the microwave oven and 20μC/cm² and 52kV/cm for the film annealed in conventional furnace, respectively. The films annealed in conventional furnace exhibited excellent retention-free characteristics at low infant periods indicating that BLT thin films can be a promise material for use in non-volatile memories. On the other hand, the pinning of domains wall causes a strong decay at low infant periods for the films annealed in the microwave furnace which makes undesireable the application for future FeRAMS memories.

Keywords: PACS; 68.55a; 77.80Dj; 81.20KaThin films; Atomic force microscopy; Dielectric properties; Fatigue

Effect of Er:YAG laser energy on the morphology of enamel/adhesive system interface by Carina Sinclér Delfino; Wanessa Christine Souza-Zaroni; Silmara Aparecida Milori Corona; Jesus Djalma Pécora; Regina Guenka Palma-Dibb (pp. 8476-8481).

The aim of this study was to evaluate in vitro the influence of Er:YAG laser energy variation to cavity preparation on the morphology of enamel/adhesive system interface, using SEM. Eighteen molars were used and the buccal surfaces were flattened without dentine exposure. The specimens were randomly assigned to two groups, according to the adhesive system (conventional total-etching or self-etching), and each group was divided into three subgroups (bur carbide in turbine of high rotation, Er:YAG laser 250mJ/4Hz and Er:YAG laser 300mJ/4Hz) containing six teeth each. The enamel/adhesive system interface was serially sectioned and prepared for SEM. The Er:YAG laser, in general, produced a more irregular adhesive interface than the control group. For Er:YAG laser 250mJ there was formation of a more regular hybrid layer with good tag formation, mainly in the total-etching system. However, Er:YAG laser 300mJ showed a more irregular interface with amorphous enamel and fused areas, for both adhesive systems. It was concluded that cavity preparation with Er:YAG laser influenced on the morphology of enamel/adhesive system interface and the tissual alterations were more evident when the energy was increased.

Keywords: Enamel; Er:YAG laser; Scanning electron microscopy

Transitions of microstructure and photoluminescence properties of the Ge/ZnO multilayer films in certain annealing temperature region by Tianhang Zheng; Ziquan Li; Jiankang Chen; Kai Shen; Kefei Sun (pp. 8482-8486).

The Ge/ZnO multilayer films have been prepared by rf magnetron sputtering. The effects of annealing on the microstructure and photoluminescence properties of the multilayers have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectrometry and photoluminescence (PL) spectrometry. The investigation of structural properties indicates that Zn₂GeO₄ has been formed with (220) texture and Zn deficiency from Ge/ZnO multilayer films in the process of annealing. However, lower Zn/Ge ratio can be improved by annealing. The annealed multilayers show three main emission bands at 532, 700, and 761nm, which originate from the transition between oxygen vacancy (Vo*) and Zn vacancies (V_Zn), the radiative recombination of quantum-confined excitons (QCE) in Ge nanocrystals, and the optical transition in the GeO color centers, respectively. Finally, the fabrication of thin film Zn₂GeO₄ from Ge/ZnO multilayer films by annealing at low temperature provides another approach to prepare the green-emitting oxide phosphor film:Zn₂GeO₄:Mn.

Keywords: PACS; 78.66.Sq; 81.15.Cd; 81.10.Jt; 78.55.−mGe/ZnO multilayers; Microstructure; Photoluminescence; Annealing

Development of copper coatings on ceramic powder by electroless technique by Rahul Sharma; R.C. Agarwala; V. Agarwala (pp. 8487-8493).

Electroless (EL) coating technique is one of the elegant ways of coating by controlling the temperature and pH of the coating bath in which there is no usage of electric current. EL nano-copper coating on ceramic particles of micron size is not reported. In this investigation, ceramic powders of ∼100μm size have been coated with copper by EL technique in the pH and temperature ranges of 12–13.5 and 60–85°C, respectively. The optimization of EL copper bath has been evaluated through the combination of process parameters like pH and temperature. The optimized value of pH is found to be 12.5 and temperature as 75°C. The coated and uncoated powders have been subjected to microstructural studies by scanning electron microscope (SEM) and the phases present have been analyzed by X-ray diffraction. An attempt has been made to understand the bonding mechanism of coating. The adherence with the substrate is attributed to the chemical and mechanical bonding at the interface. A model has been suggested for the mechanical bonding effect at the interface.

Keywords: Electroless coating; EL; Adherence; Porosity; Interface; Chemical bonding; Mechanical bonding

Spectral analysis on the surface molecular structure of modified polyvinylidene fluoride membrane by Wang Haifang; Wang Lianjun; Sun Xiuyun; Li Jiansheng; Yu Wendun (pp. 8494-8498).

Taking advantage of Fourier transform infrared spectrum and X-ray photoelectron spectroscopy, the researcher has conducted a contrastive research on the surface molecular structure of porous PVDF membrane before and after modification. Research results indicate that, though the C–F characteristic peak of the PVDF membrane still exists after modification, the peak is obviously flat, which indicates that the content of F atom decreases evidently; the results also indicate that hydroxyl characteristic peak is sharper, which indicates the content of O atom increases evidently. This proves that chemical binding force has been produced by chemical reactions on the surface of PVDF membrane during the modification. The coexistence of C–F functional group with C–OH one on the surface of PVDF membrane after modification proves that the surface features of the PVDF membrane have been successfully altered. Combination of Fourier transform infrared spectrum with X-ray photoelectron spectroscopy is proved an effective approach for analyzing the surface structure of the membrane.

Keywords: PVDF membrane; Molecular structure; Fourier transform infrared spectrum; X-ray photoelectron spectroscopy

The surface properties and the activities in catalytic wet air oxidation over CeO₂–TiO₂ catalysts by Shaoxia Yang; Wanpeng Zhu; Zhanpeng Jiang; Zhengxiong Chen; Jiangbing Wang (pp. 8499-8505).

No-noble metal CeO₂–TiO₂ catalysts prepared by sol–gel method were developed and examined for catalytic wet air oxidation (CWAO) of acetic acid. The structure of the catalysts was measured by BET, SEM, XRD, XPS and DTA-TG. We investigated the effect of the interactions of Ce and Ti on the structure of CeO₂–TiO₂ catalysts. The mechanisms of the relationships between the different content of Ti and the activity of CeO₂–TiO₂ catalysts were discussed. The results showed that the average crystal size of CeO₂ decreased and the surface areas increased; the low valence of Ce³⁺ increase, and the chemisorbed oxygen slightly decreased with the increase of Ti content on the surface of CeO₂–TiO₂ catalysts. The order of the activity in CWAO of acetic acid followed: Ce/Ti 1/1>Ce/Ti 3/1>Ce/Ti 1/3>Ce/Ti 5/1>CeO₂>TiO₂>no catalyst. In CWAO of acetic acid, the optimal atomic ratio of Ce and Ti was 1, and the highest COD removal was over 64% at 230°C, 5MPa and 180min reaction time over Ce/Ti 1/1 catalyst. The excellent activity and stability of CeO₂–TiO₂ catalysts was observed in our study.

Keywords: Catalytic wet air oxidation (CWAO); CeO; ₂; TiO; ₂; Acetic acid

Electrical properties of La₂O₃ thin films grown on TiN/Si substrates via atomic layer deposition by Nam Kyun Park; Dong Kyun Kang; Byong-Ho Kim; Sang Jin Jo; Jeong Sook Ha (pp. 8506-8509).

The electrical as well as the structural properties of La₂O₃ thin films on TiN substrates were investigated. Amorphous stoichiometric La₂O₃ thin films were grown at 300°C via atomic layer deposition technique by using lanthanum 2,2,6,6-tetramethyl-3,5-heptanedione [La(TMHD)₃] and H₂O as precursors. Post-annealing of the grown film induced dramatic changes in structural and the electrical properties. Crystalline phases of the La₂O₃ film emerged with the increase of the post-annealing temperature. Metal–insulator–metal (MIM) capacitor was fabricated to measure the electrical properties of the grown film. The dielectric constant of the La₂O₃ thin films increased with annealing temperature to reach the value of 17.3 at 500°C. The leakage current density of the film post-annealed at 400°C was estimated to be 2.78×10⁻¹⁰ and 2.1×10⁻⁸A/cm² at ±1V, respectively.

Keywords: La; ₂; O; ₃; Atomic layer deposition; high-; k; dielectrics; MIM capacitor

Surface modification of γ-TiAl alloys by acetylene plasma deposition by Suparut Narksitipan; Titipun Thongtem; Michael McNallan; Somchai Thongtem (pp. 8510-8513).

Surfaces of two γ-TiAl alloys, Ti–47at% Al–2at% Nb–2at% Cr (MJ12) and Ti–47at% Al–2at% Nb–2at% Mn+0.8at% TiB₂ (MJ47), have been modified by acetylene plasma deposition at bias voltages of −4, −5 and −6kV for 3.6×10³s (1h) and 1.44×10⁴s (4h). Knoop hardness (HK) of the alloys is increased with the increase of bias voltage and prolonged time for the deposition. HK of MJ12 and MJ47 deposited at −6kV for 1.44×10⁴ s is, respectively, 3.36 and 3.32 times as hard as the untreated alloys. SEM and AFM analyses show that the deposited alloys compose of a number of nano-dots which reflect their surface properties. The phases analyzed by XRD are in accord with the elements analyzed by EDX.

Keywords: PACS; 52.77.Dq; 81.15.-zγ-TiAl alloys; Acetylene plasma deposition; Knoop hardness; Surface morphology and roughness

Wetting behaviour of plasma sprayed oxide coatings by Mika Harju; Erkki Levänen; Tapio Mäntylä (pp. 8514-8520).

Wetting behaviour of several plasma sprayed oxide surfaces were characterised using contact angle measurements. Since surfaces contained pores and cracks, the evaluation of wetting angles led only to rough estimation of surface free energies. In order to find out the effect of atmospheric contamination the wetting behaviour of plasma-etched surfaces was followed as a function of time.It was found out that the sample preparation method had great influence on the contact angle of plasma sprayed oxide surfaces. The contact angle of plasma-etched surfaces increased when the surfaces were exposed to air. The probable reason for that was adsorption of low surface free energy contaminants to the sample surfaces.

Keywords: Plasma spraying; Wetting angle; Surface free energy; Oxides

Khillah extract as inhibitor for acid corrosion of SX 316 steel by A.Y. El-Etre (pp. 8521-8525).

The inhibitive effect of the extract of khillah ( Ammi visnaga) seeds, on the corrosion of SX 316 steel in HCl solution was determined using weight loss measurements as well as potentiostatic technique. It was found that the presence of the extract reduces markedly the corrosion rate of steel in the acid solution. The inhibition efficiency increases as the extract concentration is increased. The inhibitive effect of khillah extract was discussed on the basis of adsorption of its components on the metal surface. Negative values were calculated for the energy of adsorption indicating the spontaneity of the adsorption process. The formation of insoluble complexes as a result of interaction between iron cations and khellin, which present in the extract, was also discussed.

Keywords: Acid inhibition; Natural product; Khillah; Steel 316

The influence of the oxygen exposure on the thermal faceting of W[111] tip by Robert Bryl; Andrzej Szczepkowicz (pp. 8526-8532).

The oxygen induced faceting of the macroscopic W[111] tip has been studied for oxygen exposures in the range 0.5–31L and annealing temperatures 800–1800K using the field ion microscopy (FIM) technique. After annealing at temperatures lower than 800K, higher than 1850K or for exposures lower than 0.5L faceting was not observed. For exposures 0.5–1.9L and annealing temperatures 800–1600K well developed {112} facets with sharp edges formed. For exposures higher than 2.0L edges of the {112} facets were broadening and disappearing, what has been attributed to the formation of three-dimensional tungsten oxides. The oxides could be easily removed by annealing the tip at 1700K, what leads to formation of sharp facet edges. On the basis of these results a modified procedure of the ultrasharp tip fabrication has been proposed.

Keywords: PACS; 61.16.Fk; 68.35.BsFaceting; Oxygen; Tungsten; Microtips; Ultrasharp field emitters; Field ion microscopy; Field emission microscopy

Ion implantation induced by Cu ablation at high laser fluence by L. Torrisi; A.M. Mezzasalma; S. Gammino; J. Badziak; P. Parys; J. Wolowski; L. Laska; G. Franco (pp. 8533-8538).

High energy laser plasma-produced Cu ions have been implanted in silicon substrates placed at different distances and angles with respect to the normal to the surface of the ablated target. The implanted samples have been produced using the iodine high power Prague Asterix Laser System (PALS) using 438nm wavelength irradiating in vacuum a Cu target. The high laser pulse energy (up to 230J) and the short pulse duration (400ps) produced a non-equilibrium plasma expanding mainly along the normal to the Cu target surface. Time-of-flight (TOF) technique was employed, through an electrostatic ion energy analyzer (IEA) placed along the target normal, in order to measure the ion energy, the ion charge state, the energy distribution and the charge state distribution. Ions had a Boltzmann energy distributions with an energy increasing with the charge state. At a laser fluence of the order of 6×10⁶J/cm², the maximum ion energy was about 600keV and the maximum charge state was about 27+.In order to investigate the implantation processes, Cu depth profiles have been performed with Rutherford backscattering spectrometry (RBS) of 1.5MeV helium ions, Auger electron spectroscopy (AES) with 3keV electron beam and 1keV Ar sputtering ions in combination with scanning electron microscopy (SEM). Surface analysis results indicate that Cu ions are implanted within the first surface layers and that the ion penetration ranges are in agreement with the ion energy measured with IEA analysis.

Keywords: Laser ablation; Plasma laser; Ion implantation; RBS analysis; AES analysis

Fabrication of isotype (p-p) selenium–polyaniline heterojunction diode by electrochemical method by S.S. Joshi; C.D. Lokhande (pp. 8539-8543).

In the present work, for the first time, heterojunction has been fabricated using electrochemically deposited isotype p-selenium–p-polyaniline from a single solution bath. The structural characterization of selenium and polyaniline thin film was carried out using XRD technique. Polyaniline exhibited amorphous structure while selenium offered monoclinic ( β) phase. The junction was formed by electrodepositing polyaniline over selenium film and heating at 423K. The current density versus voltage ( J– V) plot showed the formation of a junction with ideality factor of 1.16. From J– V characteristics at different temperatures, static resistance ( R_s), dynamic resistance ( R_d), and rectification ratio of diodes were determined. Heat treatment above 448K caused junction breakdown.

Keywords: Heterojunction; Isotype; Junction ideality factor; Selenium; Polyaniline

Direct micropatterning of polymer materials by ice mold by Xinhong Yu; Rubo Xing; Shifang Luan; Zhe Wang; Yanchun Han (pp. 8544-8548).

Micropatterning of functional polymer materials by micromolding in capillaries (MIMIC) with ice mold is reported in this paper. Ice mold was selected due to its thaw or sublimation. Thus, the mold can be easily removed. Furthermore, the polymer solution did not react with, swell, or adhere to the ice mold, so the method is suitable for many kinds of materials (such as P3HT, PMMA Alq₃/PVK, PEDOT: PSS, PS, P2VP, etc.). Freestanding polymer microstructures, binary polymer pattern, and microchannels have been fabricated by the use of ice mold freely.

Keywords: Pattern; Ice mold; Capillary force

Synthesis and characterisation of hybrid carbon-alumina support by Lyudmila F. Sharanda; Yuri V. Plyuto; Igor V. Babich; Igor V. Plyuto; Anatoliy P. Shpak; Jerzy Stoch; Jacob A. Moulijn (pp. 8549-8556).

Hybrid carbon-coated alumina supports have been synthesised using 4,4′-methylenebis(phenylisocyanate) as carbon precursor. The adsorption of 4,4′-methylenebis(phenylisocyanate) on the alumina support is irreversible, the resulting organic moiety can undergo pyrolysis under elevated temperature with the formation of carbon coating on the alumina support. Carbon loading in the synthesised materials and thus a degree of coverage of the alumina surface with carbon layer can be increased by repetition of 4,4′-methylenebis(phenylisocyanate) adsorption–pyrolysis cycles. The carbon coating does not substantially influence the pore structure of the initial alumina support. Upon increasing the carbon loading, the carbon coating becomes more uniform with respect to carbon localisation both on the internal and the external surface of the alumina support. The carbon coating on an alumina support can be discriminated from carbonaceous deposits due to a difference in the steady-state surface charging of the samples. Moreover, carbonaceous surface species which associated with CO, CO and OCO groups in carbon coating can also be identified.

Keywords: Alumina support; Carbon coating; Adsorption

CO₂ laser gas assisted nitriding of Ti–6Al–4V alloy by B.S. Yilbas; C. Karatas; Uslan; O. Keles; I.Y. Usta; M. Ahsan (pp. 8557-8564).

Laser gas assisted nitriding of Ti–6Al–4V alloy is carried out and nitride compounds formed and their concentration in the surface vicinity are examined. SEM, XRD and XPS are accommodated to examine the nitride layer characteristics. Microhardness across the nitride layer is measured. Temperature field and nitrogen distribution due to laser irradiation pulse is predicted. It is found that the nitride layer appears like golden color; however, it becomes dark gold color once the laser power irradiation is increased. The δ-TiN and ɛ-TiN are dominant phases in the surface vicinity. The needle like dendrite structure replace with the feathery like structure in the surface region due to high nitrogen concentration. No porous or microcracks are observed in the nitrided layer, except at high power irradiation, in this case, elongated cracks are observed in the surface region where the nitrogen concentration is considerably high.

Keywords: Laser; Nitriding; Ti–6Al–4V; Microstructure; Phases

Investigation on mechanism of photocatalytic activity enhancement of nanometer cerium-doped titania by Yue-hua Xu; Huo-rong Chen; Zhuo-xian Zeng; Bo Lei (pp. 8565-8570).

A series of Ce–TiO₂ are prepared by the sol–gel process with ammonium cerium(IV) nitrate and tetra- n-butyl titanium as raw materials and characterized with XRD, TEM, DRS, and XPS. The aberrance (0.355) of anatase(101) plane of 0.1% Ce/TiO₂ increases compared to that of TiO₂. Cerium is found to be present as a mixture of Ce^3+/4+ oxidation states, that is, the oxidation state of some cerium in Ce–TiO₂ has changed after calcination. Ce/TiO₂ yields a large red shift compared to TiO₂. Moreover, the reflectance decreases in the visible region after cerium doped on TiO₂, and the lower the reflectance the higher the activity. Cerium appears to enhance the photocatalytic activity of Ce/TiO₂ by suppressing electron–hole recombination with electron trapping at Ce⁴⁺. 0.1% Ce/TiO₂ shows highest activity for the degradation of aqueous suspension of formaldehyde.

Keywords: Cerium-doped TiO; ₂; Cerium-doped; Formaldehyde; Sol–gel process; Photocatalytic degradation

Investigation of annealing effects on the structural, magnetic and transport properties of Co/GaAs(001) thin films by A. Sharma; S. Tripathi; R. Brajpuriya; S.M. Chaudhari (pp. 8571-8575).

Present paper deals with the structural, magnetic and transport studies of as-deposited as well as annealed Co/GaAs(001) thin film at different temperatures. The X-ray diffraction measurements show oriented growth of as-deposited Co film in the hcp (002) direction. However, the sample annealed at higher temperatures shows formation of ternary Co₂GaAs phase at the interface. Corresponding magnetic and transport measurements show decrement in magnetization and resistivity with annealing temperatures. The observed reductions in magnetization and resistivity values are mainly attributed to the formation of ternary Co₂GaAs phase at the interface.

Keywords: GaAs; Interface; Annealing; Structural; Magnetic

Subwavelength ripple formation induced by tightly focused femtosecond laser radiation by Ralph Wagner; Jens Gottmann; Alexander Horn; Ernst Wolfgang Kreutz (pp. 8576-8579).

Subwavelength ripples (< λ/4) are obtained by scanning a tightly focused beam (∼1μm) of femtosecond laser radiation ( λ=800nm, t_p=100fs) over the surface of either bulk fused silica and silicon and Er:BaTiO₃. The ripple pattern extends coherently over many overlapping laser pulses parallel and perpendicular to the polarisation. Investigated are the dependence of the ripple spacing on the spacing of successive pulses, the direction of polarisation and the material. The evolution of the ripples is investigated by applying pulse bursts with N=1 to 20 pulses. The conditions under which these phenomena occur are specified, and some possible mechanisms of ripple growth are discussed. Potential applications are presented.

Keywords: PACS; 79.20.D; 42.62.C; 61.80.BLaser induced periodic surface structures; LIPSS; Ripples; Femtosecond; Ultrashort pulsed laser; Fused silica; Silicon; Erbium barium titanate

In situ and ex situ characterisation of oxide films formed on strained stainless steel surfaces in high-temperature water by Yoichi Takeda; Tetsuo Shoji; Martin Bojinov; Petri Kinnunen; Timo Saario (pp. 8580-8588).

A possible approach in describing the role of the environment in the phenomena behind initiation and propagation of a stress corrosion crack is to assume that the transport of matter and charge through the oxide film on the material is one of the rate-controlling factors. Straining of the bulk material may affect the transport rates of ionic defects, such as vacancies and interstitials, through the oxide film. The aim of the present work has been to verify the applicability of combined slow strain rate tests (SSRT) and contact electric resistance (CER) measurements to assess the influence of strain on the electric properties of oxide films on AISI 316L stainless steel with or without prior cold work in simulated boiling water reactor (BWR) coolant conditions. The SSRT-CER measurements have been combined with ex situ characterisation of the oxide films after experiments using electron spectroscopy for chemical analysis (ESCA) and scanning electron microscopy (SEM). The results suggest that the effect of strain on the resistance of the oxide films seems to correlate with the effect of the same parameter on the Cr(III) concentration in the inner layer of the oxide. In addition, important differences between the concentration of Ni and Fe in the outer layer formed on stressed and unstressed surface have been observed. Based on the mixed-conduction model for oxide films, an attempt is made to evaluate the effect of straining on the electric properties of the oxide films and to correlate these effects with the changes in film composition and structure.

Keywords: Stainless steel; Simulated nuclear reactor coolant; Contact electric resistance; Slow strain rate test; Oxide film; Kinetic model

Infrared spectroscopic study of thermal annealing effects of hydrocarbon species on a Si surface exposed to methane plasma by Masanori Shinohara; Keitaro Iwatsuji; Teruaki Katagiri; Hiromichi Shibata; Yoshinobu Matsuda; Hiroshi Fujiyama (pp. 8589-8592).

We have investigated the thermal annealing effects of hydrocarbon species on the methane-plasma exposed silicon surface, investigated by in situ infrared absorption spectroscopy (IRAS) in multiple internal reflection (MIR) geometry. The proportion of types of hydrocarbon species is not remarkably changed in the hydrocarbon network that consists of sp-, sp²- and sp³-CH_X species by annealing at moderate temperatures. On the other hands, the proportion is drastically changed in the network that is mainly composed of sp³-CH_X species by annealing at moderate temperatures. It suggests that excess CH₃ species in the film is not stable against thermal annealing and would be converted to sp³-CH_1–2 species by annealing at moderate temperatures. And the data also show that sp²-CH species is more stable against the thermal annealing than sp³-hydrocarbon species.

Keywords: PACS; 31.10; 81.40.E; 82.80.CThermal annealing; Hydrocarbon species; Infrared absorption spectroscopy

Effect of borohydride as reducing agent on the structures and electrochemical properties of Pt/C catalyst by Hong-Chao Ma; Xin-Zhong Xue; Jian-Hui Liao; Chang-Peng Liu; Wei Xing (pp. 8593-8597).

In this paper, we found that boron deposited on the surface of support when sodium borohydride used as reducing agent during the preparation of Pt/C catalyst. The deposition of boron markedly reduces particle size of Pt, raises electrochemical active surface (EAS) area of catalyst and electrochemical activity for hydrogen evolution or oxygen reduction reaction (ORR) compared with which prepared using other reducing agents (hydrogen and formaldehyde).

Keywords: Pt/C catalysts; Reducing agents; Sodium borohydride; Deposition of boron; Hydrogen evolution

The removal of sodium dodecylbenzene sulfonate surfactant from water using silica/titania nanorods/nanotubes composite membrane with photocatalytic capability by Haimin Zhang; Xie Quan; Shuo Chen; Huimin Zhao; Yazhi Zhao (pp. 8598-8604).

This paper reports experimental results on removal of sodium dodecylbenzene sulfonate (SDBS), using silica/titania nanorods/nanotubes composite membrane with photocatalytic capability. This multifunctional composite membrane has been successfully prepared from colloidal X-silica/titania sols ( X denotes molar percent of silica) by the sol–gel technique. The prepared nanorods/nanotubes composite membranes were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), scanning probe microscope (SPM) and UV–vis diffuse reflectance spectra (DRS). XRD patterns confirmed that the embedding of amorphous silica into nanophase titania matrix helped to increase the thermal stability of titania and control the size of titania particles. The small size titania particles with anatase phase played an important role in formation of silica/titania nanorods/nanotubes composite membranes with photocatalytic capability. The percentage of anatase phase titania reached 93% when 20%-silica/titania nanorods/nanotubes composite membrane calcined at 400°C for 2h. Most (95%) of the pore volume was located in mesopores of diameters ranging from 1.4 to 10nm. The experimental results showed that the removal of SDBS achieved 89% after 100min by combining the photocatalysis with membrane filtration techniques. Although the SDBS was not completely decomposed by photocatalysis, the degradation of the SDBS helped to enhance composite membrane flux and prevent membrane fouling. It was possible to treat successfully surfactant wastewater using multifunctional silica/titania nanorods/nanotubes composite membrane by means of a continuous process; this could be interesting for industrial applications.

Keywords: Silica/titania composite membrane; Photocatalysis; Membrane separation; SDBS

Electrolytical production of Ni+Mo+Si composite coatings with enhanced content of Si by J. Kubisztal; A. Budniok (pp. 8605-8610).

Ni+Mo+Si composite coatings were prepared by co-deposition of nickel with molybdenum and silicon powders from a nickel solution in which Mo and Si particles were suspended by stirring. The layers have been deposited on a carbon steel substrate (St3S) under galvanostatic conditions. The content of Si in deposited layers was about 2–5wt.% depending on deposition current density and the value of electric charge. For comparison Ni+Mo composite coatings were obtained under analogous current conditions. Composite coatings of enhanced Si content (15wt.%) were deposited from an electrolyte in which 40g/dm³ of Si covered with electroless plated nickel was dispersed. Deposition current density was equal 0.1A/cm² and the value of electric charge Q=500C/cm². The thickness of the coatings was about 100–300μm depending on their kind, electric charge and the deposition current density. Surface and cross-section morphology were investigated by scanning electron microscope (SEM). All deposited coatings are characterized by great, developed surface area. No internal stresses causing their cracking were observed. Chemical composition of the layers was determined by X-ray fluorescence spectroscopy (XRF) method and quantitative X-ray analysis (QXRD). It was stated, that the content of molybdenum and silicon in Ni+Mo+Si coatings depends on deposition current density and the amount of the powder in bath. The results of structural investigation of the obtained layers by the X-ray diffraction (XRD) method show, that they consist in crystalline Mo or Mo and Si phases built into Ni matrix. Moreover, Ni+Mo+Si composite coatings were modified by thermal treatment. It has been found that the thermal treatment of Ni+Mo+Si composite coatings caused that the new phases (NiSi, Mo₂Ni₃Si and Ni₆Mo₆C_1.06) were obtained.

Keywords: Nickel; Molybdenum; Silicon; Electrolytic composite coatings; Galvanostatic deposition

The effects of Co-metal clusters on exchange bias for Co-doped NiO/FeNi bilayers by Yaxin Wang; Jie Xiong; Yongjun Zhang; Liang Sun; Biao You; Jun Du; An Hu; Mu Lu (pp. 8611-8614).

Co-doped NiO inhomogeneous films were synthesized by sputtering metallic Co chips and NiO together and the exchange bias of bilayers Co-doped NiO/FeNi was investigated. When Co content was up to 25.2%, the exchange bias field H_E at the room temperature increased to the maximum which was about three times compared to the undoped-bilayers. With further increase of Co content, the exchange bias field H_E and blocking temperature T_B decreased. Analysis suggests that the configuration of nanometer-sized Co-metal clusters enchased into NiO matrix played an important role in the change of magnetic behavior for the bilayers.

Keywords: Exchange bias; Co-metal clusters; Bilayers

Effects of 2-amino-5-(ethylthio)-1,3,4-thiadiazole on copper corrosion as a corrosion inhibitor in 3% NaCl solutions by El-Sayed M. Sherif (pp. 8615-8623).

Effects of 2-amino-5-(ethylthio)-1,3,4-thiadiazole (ATD) on copper corrosion as a corrosion inhibitor in de-aerated, aerated and oxygenated 3% NaCl solutions have been studied using potentiodynamic polarization, potentiostatic current–time, electrochemical impedance spectroscopic (EIS), weight loss and pH measurements along with scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) investigations. Potentiodynamic polarization measurements indicated that the presence of ATD in these solutions greatly decreases cathodic, anodic and corrosion currents. Potentiostatic current–time measurements and SEM/EDX investigations also showed that the ATD molecules are strongly adsorbed on the copper surface preventing it from being corroded easily. EIS measurements revealed that the charge transfer resistance increases due to the presence of ATD, and this effect increases with oxygen content in the solution. Weight loss measurements gave an inhibition efficiency of about 83% with 1.0mM ATD present, increasing to about 94% at the ATD concentration of 5.0mM. Results together are internally consistent with each other, showing that ATD is a good mixed-type inhibitor for copper corrosion with its inhibition efficiency increasing in the order of oxygenated>aerated>de-aerated 3% NaCl solutions.

Keywords: 2-Amino-5-(ethylthio)-1,3,4-thiadiazole; Copper corrosion; Corrosion inhibitor; 3% NaCl solution

Growth of Rh nanoclusters on TiO₂(110): XPS and LEIS studies by László Óvári; János Kiss (pp. 8624-8629).

Rhodium clusters were prepared by evaporation on a nearly stoichiometric TiO₂(110) surface. The growth of metal nanoparticles, as a function of rhodium coverage, could be followed by monitoring the Rh 3d_5/2 XP peak position and by low energy ion scattering spectroscopy (LEIS). The substrate temperature in the 160–300K regime during evaporation significantly influences the cluster size, leading to smaller crystallites at low temperature. Annealing the surface results in the agglomeration of rhodium, which commenced at lower temperature for smaller clusters. At high temperatures (∼900K) encapsulation of rhodium also occurred.

Keywords: PACS; 81.16.DnTitania; Model catalysis; Rhodium nanoclusters; X-ray photoelectron spectroscopy; Low energy ion scattering spectroscopy

The corrosion inhibition and gas evolution studies of some surfactants and citric acid on lead alloy in 12.5M H₂SO₄ solution by A. Tizpar; Z. Ghasemi (pp. 8630-8634).

The inhibition action of the citric acid and three surfactants: sodium dodecyl sulfate (SDS), t-octyl phenoxy polyethoxyethanol (Triton X-100), sodium dodecyl benzene sulphonate (SDBS) on the corrosion behavior and gas evolution of Pb–Sb–As–Se was investigated in 12.5M H₂SO₄ solution with linear sweep polarization, cyclic voltammetry and weight loss measurements methods. The results drawn from different techniques are comparable. It was found that these surfactants and citric acid act as good inhibitors for the corrosion of lead alloy in H₂SO₄ solution. SDS inhibited most effectively the lead alloy corrosion among the three surfactants and citric acid. The inhibition efficiency for the inhibitors decreases in the order: SDS>SDBS>Triton X-100>citric acid>blank. The inhibition efficiency increases with rising of the inhibitor concentration. In this work, the effect of the inhibitors on hydrogen and oxygen evolution was studied. In addition, it was found that the adsorption of used inhibitors on lead alloy surface follows Langmuir isotherm.

Keywords: Corrosion; Surfactant inhibitors; Lead alloys; Inhibitors

Improvement of polyacrylate coating by filling modified nano-TiO₂ by Yunhua Chen; An Lin; Fuxing Gan (pp. 8635-8640).

Nano-TiO₂ is modified by a method, by which nano-TiO₂ first reacts with silane coupling agent WD-70 with double bond group which subsequently copolymerizes with methyl methacrylate and butyl acrylate to produce a thin polymer shell on the nanoparticles. The modified nanoparticles have stable organophilicity. They are applied to polyacrylate coating and performances of the coating are measured by different methods. The modification of nano-TiO₂ particles can improve their dispersibility in coating, enhance hardness of coating and reduce water absorption and permeability of polyacrylate coating. The mechanism has been analyzed in this paper.

Keywords: Nano-TiO; ₂; Modification; Polyacrylate coating; Water absorption; Permeability

Cell patterning without chemical surface modification: Cell–cell interactions between printed bovine aortic endothelial cells (BAEC) on a homogeneous cell-adherent hydrogel by C.Y. Chen; J.A. Barron; B.R. Ringeisen (pp. 8641-8645).

Cell printing offers the unique ability to directly deposit one or multiple cell types directly onto a surface without the need to chemically pre-treat the surface with lithographic methods. We utilize biological laser printing (BioLP^™) to form patterns of bovine aortic endothelial cells (BAECs) onto a homogeneous cell adherent hydrogel surface. These normal cells are shown to retain near-100% viability post-printing. In order to determine whether BAECs encountered shear and/or heat stress during printing, immunocytochemical staining experiments were performed to detect potential expression of heat shock proteins (HSP) by the deposited cells. Printed BAECs expressed HSP at levels similar to negative control cells, indicating that the BioLP process does not expose cells to damaging levels of stress. However, HSP expression was slightly higher at the highest laser energy studied, suggesting more stress was present under these extreme conditions. Printed BAECs also showed preferential asymmetric growth and migration towards each other and away from the originally printed pattern, demonstrating a retained ability for the cells to communicate post-printing.

Keywords: BioLP; Cell patterning; Cell printing; Tissue engineering; BAECs

Surface analysis of heat-treated Mong Hsu rubies by S. Achiwawanich; N. Brack; B.D. James; J. Liesegang (pp. 8646-8650).

Mong Hsu rubies have been heat treated in air at 1100, 1200, 1300, 1400, 1500 and 1600°C. Their visual appearance and surface analysis (XPS) after each stage of heating have been monitored. The characteristic blue core regions of untreated ruby become slightly faded at 1100°C and completely disappear at temperatures above 1500°C. Trace amounts of Na, Ca, Si and Fe were found on the surface of untreated stones. Ti was first detected after heating to 1100°C. Plots of detected surface concentrations of elements versus temperature show that the highest concentration of Fe occurred at 1300°C while surface concentrations of Ti appeared to show two maxima near 1300 and 1500°C. The results suggest that both the changing oxidation state of Fe²⁺ to Fe³⁺ and the diffusion of the Fe and Ti ions with temperature are responsible for the color changes through decreasing Fe²⁺ to Ti⁴⁺ charge transfer.

Keywords: PACS; 79.60.−i; 82.80.PvPhotoelectron spectroscopy; Ruby; Heat treatment; Diffusion

Fabrication and characterization of sputtered titanium dioxide films by A.A. Akl; H. Kamal; K. Abdel-Hady (pp. 8651-8656).

TiO₂ thin films were prepared under various conditions by using a reactive RF sputtering technique. The structural, optical and electrical characteristics of the films have been investigated. All as-deposited films were amorphous. After annealing at T>673K, the crystallinity of the observed tetragonal anatase phase appeared improved. The optical band gap, determined by using Tauc plot, has been found to amount to 3.38±0.03 and 3.21±0.03eV for the direct and indirect transition, respectively. Also the complex optical constants for the wavelength range 300–2500nm are reported. Using the two-point probe technique, the dark resistivity has been measured as a function of the film thickness, d. The resistivity, �?, of the samples has been found to decrease markedly with increasing thickness, but only for d<100nm. The behaviour of �?d versus d was found to fit properly with the Fuchs and Sondheimer relation with parameters �?_o=4.95×10⁶Ωcm and mean free path, l=310±2nm. The log �? versus 1/ T curves show three distinct regions with values for the activation energy of 0.03±0.01, 0.17±0.01 and 0.50±0.02eV, respectively.

Keywords: Titanium oxide; Thin films and sputtering

Fabrication and vacuum annealing of transparent conductive Ga-doped Zn_0.9Mg_0.1O thin films prepared by pulsed laser deposition technique by Zhiqiang Chen; Guojia Fang; Chun Li; Su Sheng; Guanwen Jie; Xing-Zhong Zhao (pp. 8657-8661).

In this study, highly transparent conductive Ga-doped Zn_0.9Mg_0.1O (ZMO:Ga) thin films have been deposited on glass substrates by pulsed laser deposition (PLD) technique. The effects of substrate temperature and post-deposition vacuum annealing on structural, electrical and optical properties of ZMO:Ga thin films were investigated. The properties of the films have been characterized through Hall effect, double beam spectrophotometer and X-ray diffraction. The experimental results show that the electrical resistivity of film deposited at 200°C is 8.12×10⁻⁴Ωcm, and can be further decreased to 4.74×10⁻⁴Ωcm with post-deposition annealing at 400°C for 2h under 3×10⁻³Pa. In the meantime, its band gap energy can be increased to 3.90eV from 3.83eV. The annealing process leads to improvement of (002) orientation, wider band gap, increased carrier concentration and blue-shift of absorption edge in the transmission spectra of ZMO:Ga thin films.

Keywords: ZMO:Ga films; Pulsed laser deposition (PLD); Vacuum annealing; Substrate temperature; Band gap energy

Growth kinetics of iron boride layers: Dimensional analysis by I. Campos; R. Torres; G. Ramírez; R. Ganem; J. Martínez (pp. 8662-8667).

Dimensional analysis is presented as a powerful tool in the study of the paste boriding process. In particular, a dimensional method is used to study the growth kinetics of the boride layers FeB and Fe₂B. Experiments were performed in AISI 1045 steel and AISI M2 steel, to test the suggested model. Samples of 1045 steel were prepared and treated using boron paste thickness of 3–5mm, at temperatures of 1193, 1223 and 1273K, with 2, 4 and 6h of treatment time. The M2 specimens had boron paste thickness of 3 and 4mm and temperatures of 1223, 1253 and 1273K for 2 and 6h. Results indicate that the growth of boron layers obeys power laws of the form y= αx^β, where α and β constants are a function of the material and the interface of interest. Validation of the model was carried out using experimental data with an average error percentage of 7.6% for Fe₂B in 1045 steel, 15.8% for FeB and 3.4% for Fe₂B in M2 steel.

Keywords: Dimensional analysis; Growth kinetics; Boriding process; Boride layers

Nanostructured ZnO films obtained by a basic erosion method by Xiaoxin Liu; Zhengguo Jin; Zhifeng Liu; Ke Yu; Shaojing Bu (pp. 8668-8672).

A novel methodology based on the basic erosion of as-grown ZnO rod films was developed to prepare ZnO nanoplates array and nanowires network films. The different morphology was obtained by adjusting the erosion time with ammonium solution as the erodent. The XRD, TEM and HRTEM analysis showed that the synthesized ZnO nanostructure had a single crystalline hexagonal wurtzite structure. The nanoplates formed due to the dissolution of the polar planes of hexagonal rod crystals. The formation process of ZnO nanowire resulted from dissolution-regrowth was illustrated by the aid of TEM and HRTEM characterization, which runs as follows: nanoparticle packing, crystallization and oriented attachment of grain domains, formation of the single crystalline nanowire ultimately.

Keywords: ZnO; Films; Basic erosin; Nanowire; Nanoplate

Characterization of HfO_xN_y gate dielectrics using a hafnium oxide as target by M. Liu; Q. Fang; G. He; L.Q. Zhu; L.D. Zhang (pp. 8673-8676).

Hafnium oxynitride (HfO_xN_y) gate dielectric has been deposited on Si (100) by means of radio frequency (rf) reactive sputtering using directly a HfO₂ target in N₂/Ar ambient. The thermal stability and microstructural characteristics for the HfO_xN_y films have been investigated. XPS results confirmed that nitrogen was successfully incorporated into the HfO₂ films. XRD analyses showed that the HfO_xN_y films remain amorphous after 800°C annealing in N₂ ambient. Meanwhile the HfO_xN_y films can also effectively suppress oxygen diffusion during high temperature annealing and prevent interface layer from forming between HfO_xN_y films and Si substrates. AFM measurements demonstrated that surface roughness of the HfO_xN_y films increase slightly as compared to those pure HfO₂ films after post deposition annealing. By virtue of building reasonable model structure, the optical properties of the HfO_xN_y films have been discussed in detail.

Keywords: PACS; 77.55.+f; 77.84.Bw; 78.20.CiHigh-; k; Crystallization; Interface; Optical properties

Local heating in noble metal nanocontacts under high biases at 77K by Makusu Tsutsui; Yumi Teramae; Shu Kurokawa; Akira Sakai (pp. 8677-8682).

Effects of local heating of noble metal nanocontacts under high biases at 77K are investigated by measuring the bias dependence of the two-level fluctuation (TLF) frequency of the contact conductance. The TLF frequency increases exponentially in a bias range from 0.2 to 0.6V for Au and Cu nanocontacts. This result indicates that the effective contact temperature of these contacts remains unchanged up to 0.6V, in accordance with the theoretical prediction by Todorov et al. [T.N. Todorov, J. Hoekstra, A.P. Sutton, Phys. Rev. Lett. 86 (2001) 3606]. In contrast, the TLF frequency of Ag nanocontacts starts to increase more rapidly above 0.45V than that of Au and Cu nanocontacts. The steep rise in the TLF frequency is possibly attributed to a poor heat transfer to the bulk part of the contact and a resulting rapid increase in the effective temperature.

Keywords: PACS; 73.63.Rt (nanoscale contacts)Nanocontacts; Nanowires; Two-level fluctuation; Contact instability; Local heating

Facile route to high-density, ordered ZnO nanowire arrays and their photoluminescence properties by Wei Chen; Xiaoming Tao; Yuyang Liu; Xiaohong Sun; Zhigang Hu; Bin Fei (pp. 8683-8687).

A simple template-directed wet chemistry route based on traditional thermal decomposition technique has been developed for the preparation of high-density, ordered ZnO nanowire arrays. The fabrication was performed at relative low temperature without involving complex procedures, sophisticated equipment and rigorous experiment conditions, thereby providing a straightforward and mild method to produce metal/metal oxide ordered nanostructures. The nanowire array system was evaluated by SEM, XRD, TEM and PL. A stable luminescence at 425nm was present.

Keywords: PACS; 81.16Nanowire arrays; ZnO; Thermal decomposition; Photoluminescence

Characterization of Cu additive FePt–C granular films by W.B. Mi; Hui Liu; Z.Q. Li; P. Wu; E.Y. Jiang; H.L. Bai (pp. 8688-8694).

FePt–C granular films doped with different Cu atomic fractions ( x_Cu) were fabricated using facing-target sputtering at room temperature and subsequently annealed at 650°C. Structural analyses reveal that the as-deposited films are in amorphous state. Appropriate Cu addition ( x_Cu=14) can improve the ordering of L1₀ FePt phase, and excessive Cu doping destroys the formation of ordered L1₀ phase with the appearance of Fe₃C and CuPt phases. Besides, preferential graphitization of amorphous carbon (a-C) occurs near large metal particles upon annealing. Annealing turns the as-deposited superparamagnetic films into ferromagnetic associated with coercivity peaks at x_Cu=14, drops from ∼11.2kOe at 5K to ∼7.2kOe at 300K in a 50kOe field.

Keywords: PACS; 75.75.+a; 75.70.Ak; 75.50.Vv; 72.80.TmGranular/nanocomposite films; L1; ₀; phase; FePt films; Graphitization; Magnetic properties

X-ray photoelectron spectroscopy study of pyrolytically coated graphite platforms submitted to simulated electrothermal atomic absorption spectrometry conditions by Frine Ruiz; Zully Benzo; Manuelita Quintal; �?ngel Garaboto; Alberto Albornoz; Joaquín L. Brito (pp. 8695-8701).

The present work is part of an ongoing project aiming to a better understanding of the mechanisms of atomization on graphite furnace platforms used for electrothermal atomic absorption spectrometry (ETAAS). It reports the study of unused pyrolytic graphite coated platforms of commercial origin, as well as platforms thermally or thermo-chemically treated under simulated ETAAS analysis conditions. X-ray photoelectron spectroscopy (XPS) was employed to study the elements present at the surfaces of the platforms. New, unused platforms showed the presence of molybdenum, of unknown origin, in concentrations up to 1at.%. Species in two different oxidations states (Mo⁶⁺ and Mo²⁺) were detected by analyzing the Mo 3d spectral region with high resolution XPS. The analysis of the C 1s region demonstrated the presence of several signals, one of these at 283.3eV related to the presence of Mo carbide. The O 1s region showed also various peaks, including a signal that can be attributed to the presence of MoO₃. Some carbon and oxygen signals were consistent with the presence of CO and C–O– (probably C–OH) groups on the platforms surfaces. Upon thermal treatment up to 2900°C, the intensity of the Mo signal decreased, but peaks due to Mo oxides (Mo⁶⁺ and Mo⁵⁺) and carbide (Mo²⁺) were still apparent. Thermo-chemical treatment with 3vol.% HCl solutions and heating up to 2900°C resulted in further diminution of the Mo signal, with complete disappearance of Mo carbide species. Depth profiling of unused platforms by Ar⁺ ion etching at increasing time periods demonstrated that, upon removal of several layers of carbonaceous material, the Mo signal disappears suggesting that this contamination is present only at the surface of the pyrolytic graphite platform.

Keywords: Molybdenum; Pyrolytically coated graphite; L’vov platforms; ETAAS; XPS

Low cost wavelength filter of SiGe photodetector with a-Si:H capped layer by J.D. Hwang; W.T. Chang; Y.H. Chen; K.H. Hseih; P.S. Chen; J.C. Liu (pp. 8702-8705).

The strained Si_0.8Ge_0.2 film has been prepared onto Si substrate by using an ultrahigh-vacuum chemical vapor deposition system. A low cost wavelength filter of photodetector has been demonstrated for the first time. This filter was simply carried out by just inserting a 60nm thick a-Si:H capped layer onto Si_0.8Ge_0.2 thin film. The room-temperature photoluminescence shows that the sample with Si_0.8Ge_0.2 layer has a tendency to shift wavelength into longer regime than that of Si substrate. The full width at half maximum (FWHM) was 185nm for Si_0.8Ge_0.2 photodetector without a-Si:H capped. By inserting a 60nm thick a-Si:H capped layer, the FWHM was narrowed into 97nm. This demonstrates that the a-Si:H capped layer has an ability acted as wavelength filter in our study.

Keywords: PACS; 85.30; 85.60; 85.60GWavelength filter; SiGe; Photodetector; a-Si:H

Effect of oxidation on the optical and surface properties of AlGaN by X.L. Wang; D.G. Zhao; J. Chen; X.Y. Li; H.M. Gong; H. Yang (pp. 8706-8709).

The chemical properties of Al_xGa1−_xN surfaces exposed to air for different time periods are investigated by atomic force microscopy (AFM), photoluminescence (PL) measurement and X-ray photoelectron spectroscopy (XPS). PL and AFM results show that Al_xGa1−_xN samples exhibit different surface characteristics for different air-exposure times and Al contents. The XPS spectra of the Al 2p and Ga 2p core levels indicate that the peaks shifted slightly, from an AlN to an AlO bond and from a GaN to a GaO bond. All of these results show that the epilayer surface contains a large amount of Ga and Al oxides.

Keywords: PACS; 81.40Wx; 81.65.−bOxidation; AlGaN; Surface morphology

Corrosion of graphite in industrial phosphoric acid by A. Guenbour; H. Iken; N. Kebkab; A. Bellaouchou; R. Boulif; A. Ben Bachir (pp. 8710-8715).

The electrochemical corrosion of graphite in industrial phosphoric acid solutions was studied using polarisation curves analysis, cyclic voltammetry, MEB–EDS and secondary ions mass spectroscopy (SIMS). The polarisation curves indicated that graphite has a passive behaviour and the increase of temperature induces an increase of the corrosion rate and the passive current density. The cyclic voltammetry analysis was performed to verify the surface phenomenon of graphite surface and confirmed the role of adsorption oxygen in material corrosion. Spectroscopic analysis (EDS and SIMS) showed that the majority of industrial phosphoric acid impurities were present in the graphite composition indicating that metallic oxides are not the only components of this layer. The presence of these impurities on the graphite induces an increase of corrosion by swelling, exfoliation and cracking.

Keywords: Corrosion; Graphite; Electrochemical analysis; Characterisation method; Phosphoric acid

UV protection filters by dielectric multilayer thin films on Glass BK-7 and Infrasil 301 by M.M. Abdel-Aziz; Osama A. Azim; L.A. Abdel-Wahab; Mohamed M. Seddik (pp. 8716-8723).

The increasing use of Ultraviolet (UV) light in medicine, industrial environments, for cosmetic use, and even in consumer products necessitates that greater attention be paid to the potential hazards of this type of electromagnetic radiation. To avoid any adverse effects of exposure to this type of radiation, four suitable protection filters were produced to block three UV bands (UVA, UVB, and UVC). The design structure of the required dielectric multilayer filters was done by optical thin film technology using the absorbing property of UV radiation for the substrates and dielectric materials. The computer analyses of the multilayer filter formulas were prepared using Macleod Software for the production processes. The deposition technique was achieved on optical substrates (Glass BK-7 and Infrasil 301) by dielectric material combinations including Titanium dioxide (Ti₂O₃), Hafnium dioxide (HfO₂), and Lima (mixture of oxides SiO₂/Al₂O₃); deposition being achieved using an electron beam gun. The output results of the theoretical and experimental transmittance values for spectral band from 200nm to 800nm were discussed in four processes. To analyze the suitability for use in ‘real world’ applications, the test pieces were subjected to the durability tests (adhesion, abrasion resistance, and humidity) according to Military Standard MIL-C-675C and MIL-C-48497A.

Keywords: UV protection filter; Multilayer coating; Deposition using electron beam gun

Controllable fabrication and characterization of biocompatible core-shell particles and hollow capsules as drug carrier by Lingyun Hao; Xinglong Gong; Shouhu Xuan; Hong Zhang; Xiuqing Gong; Wanquan Jiang; Zuyao Chen (pp. 8724-8733).

SiO₂@CdSe core-shell particles were fabricated by controllable deposition CdSe nanoparticles on silica colloidal spheres. Step-wise coating process was tracked by the TEM and XRD measurements. In addition, SiO₂@CdSe/polypyrrole(PPy) multi-composite particles were synthesized based on the as-prepared SiO₂@CdSe particles by cationic polymerization. The direct electrochemistry of myoglobin (Mb) could be performed by immobilizing Mb on the surface of SiO₂@CdSe particles. Immobilized with Mb, SiO₂@CdSe/PPy-Mb also displayed good bioelectrochemical activity. It confirmed the good biocompatible property of the materials with protein. CdSe hollow capsules were further obtained as the removal of the cores of SiO₂@CdSe spheres. Hollow and porous character of CdSe sub-meter size capsules made them becoming hopeful candidates as drug carriers. Doxorubicin, a typical an antineoplastic drug, was introduced into the capsules. A good sustained drug release behavior of the loading capsules was discovered via performing a release test in the PBS buffer (pH 7.4) solution at 310k. Furthermore, SiO₂@CdSe/PPy could be converted to various smart hollow capsules via selectively removal of their relevant components.

Keywords: Core-shell particles; Hollow capsules; Bioactivity; Drug carrier

Structure and optical properties of ZnS thin films grown by glancing angle deposition by Sumei Wang; Xiaoyong Fu; Guodong Xia; Jianguo Wang; Jianda Shao; Zhengxiu Fan (pp. 8734-8737).

The glancing angle deposition (GLAD) technique was used to deposit ZnS films by electron beam evaporation method. The cross sectional scanning electron microscopy (SEM) image illustrated a highly orientated microstructure composed of slanted column. The atomic force microscopy (AFM) analysis indicated that incident flux angle had significant effects on the nodule size and surface roughness. Under identical nominal thickness, the actual thickness of the GLAD films is related to the incident flux angle. The refractive index and in-plane birefringence of the GLAD ZnS films were discussed, and the maximum birefringence Δ n=0.036 was obtained at incident flux angle of α=80°. Therefore, the glancing angle deposition technique is a promising way to create a columnar structure with enhanced birefringent property.

Keywords: PACS; 81.15.Ef; 68.55.Jk; 78.20.FmGlancing angle deposition; Microstructure; Anisotropy; Birefringence

Photoinduced effect in Ga–Ge–S based thin films by S.H. Messaddeq /; M. Siu Li; S. Inoue; S.J.L. Ribeiro; Y. Messaddeq (pp. 8738-8744).

Glassy films of Ga₁₀Ge₂₅S₆₅ with 4μm thickness were deposited on quartz substrates by electron beam evaporation. Photoexpansion (PE) (photoinduced increase in volume) and photobleaching (PB) (blue shift of the bandgap) effects have been examined. The exposed areas have been analyzed using perfilometer and an expansion of 1.7μm (Δ V/ V≈30%) is observed for composition Ga₁₀Ge₂₅S₆₅ exposed during 180min and 3mW/cm² power density. The optical absorption edge measured for the film Ge₂₅Ga₁₀S₆₅ above and below the bandgap show that the blue shift of the gap by below bandgap photon illumination is considerable higher (Δ E_g=440meV) than Δ E_g induced by above bandgap illumination (Δ E_g=190meV). The distribution of the refraction index profile showed a negative change of the refraction index in the irradiated samples (Δ n=−0.6). The morphology was examined using a scanning electron microscopy (SEM). The chemical compositions measured using an energy dispersive analyzer (EDX) indicate an increase of the oxygen atoms into the irradiated area. Using a Lloyd's mirror setup for continuous wave holography it was possible to record holographic gratings using the photoinduced effects that occur in them. Diffraction efficiency up to 25% was achieved for the recorded gratings and atomic force microscopy images are presented.

Keywords: Chalcogenide; Thin films; Photoexpansion; Photobleacing; Refraction index; Diffraction gratings

Effect of solution molarity on the characteristics of vanadium pentoxide thin film by Alaa A. Akl (pp. 8745-8750).

Vanadium pentoxide (V₂O₅) thin films have been prepared by spray pyrolysis technique. The influence of solution molarity on the characteristics of the V₂O₅ has been investigated. X-ray diffraction analysis (XRD) showed that, the films deposited at ≥0.1M were orthorhombic structure with a preferential orientation along 〈001〉 direction. Moreover, the crystallinity was improved by increasing solution molarity. The microstructure parameters have been evaluated by using a single order Voigt profile method. The optical band gaps, determined by using Tauc plot, have been found to be 2.50±0.02 and 2.33±0.02eV for the direct and indirect allowed transition, respectively. Also the complex optical constants for the wavelength range 300–2500nm are reported. At room temperature, the dark conductivity as a function of solution molarity showed the range of 5.74×10⁻²±0.03 to 3.36×10⁻¹±0.02Ω⁻¹cm⁻¹. While at high temperature, the behaviour of electrical conductivity dominated by grain boundaries. The values of activation energy and potential barrier height were 0.156±0.011 and 0.263±0.012eV, respectively.

Keywords: Vanadium pentoxide; Thin films; Spray pyrolysis

Desorption of surfactant and sintering of surface-modified Pd_xNi1−_x nanoparticles by Kuan-Wen Wang; Shu-Ru Chung; Wei-Hsiu Hung; Tsong P. Perng (pp. 8751-8755).

A series of Pd_xNi1−_x nanoparticles in a diameter of 6–7nm were prepared by wet chemical reduction. They were then modified with two surfactants, stearic acid (SA) and polyethylene glycol (PEG). Desorption of the surfactant was studied using a temperature programmed desorption technique, and the sintering behavior of surface-modified Pd_xNi1−_x nanoparticles was examined. Since surface energy of the nanoparticles depends on the alloy composition, it can be correlated with the desorption temperature of surfactant from the nanoparticle surface. Because Ni has a higher surface energy, the surfactant desorption temperature increases as the Ni content increases. With the same stoichiometry, the desorption temperature of SA is always higher than that of PEG. The SA-modified nanoparticles have higher thermal stability and are less sintered than PEG-modified nanoparticles. The sintering and growth behavior of the nanoparticles can be correlated with variation of surface energy due to different surface modification.

Keywords: PACS; 81.05.Ys; 81.20.Ev; 81.20.Fw; 81.70.Pg; 82.65.-iNanoparticles; Pd–Ni; Sintering; Surface modification; Stearic acid; Polyethylene glycol

Texture control of Pb(Zr, Ti)O₃ thin films with different post-annealing processes by S.W. Jiang; Q.Y. Zhang; W. Huang; B. Jiang; Y. Zhang; Y.R. Li (pp. 8756-8759).

The non-crystalline Pb(Zr, Ti)O₃ thin films sputtered on Pt(111)/Ti/SiO₂/Si(100) substrates at room temperature were crystallized by conventional furnace annealing (CFA) and rapid thermal annealing (RTA), respectively. It was found that the RTA process favored the (111)-preferred orientation in lead zirconate titanate (PZT) thin films while the CFA process favored the (100)-preferred orientation. The origin of the different orientation selection might be due to the different epitaxial nucleation mechanism. The long heating duration would lead to the aggregation of Pb and the formation of PbO(100) on film surface; therefore, the nucleation at the PbO(100)/PZT interface on film surface might lead to the (100)-preferred orientation. However, the nucleation at the PZT/Pt(111) electrode interface by RTA process would result in the formation of (111)-preferred orientation. The RTA-derived (111)-preferentially oriented PZT thin films exhibited a high remnant polarization of 35μC/cm².

Keywords: PACS; 81.10.Aj; 77.55.+f; 64.70.Kb; 68.55.JkLead zirconate titanate; Post-annealing; Film orientation; Ferroelectricity

An investigation into the surface topology and thickness profile of functional ceramic spinel manganate sputtered, evaporated and screen-printed layers by R. Schmidt; A. Basu; A.W. Brinkman; Z. Klusek; W. Kozlowski; S. Datta; A. Stiegelschmitt; A. Roosen (pp. 8760-8767).

In this paper an atomic force microscopy and scanning electron microscopy analysis of the surface grain structure of negative temperature coefficient of resistance (NTCR) thermistor nickel manganate layers produced by radio frequency (RF) magnetron sputtering, electron-beam evaporation and screen-printing is presented. Thin sputtered and evaporated films exhibited a dense low porosity surface with evidence for grain alignment in a brick layer fashion, whereas thick screen-printed layers displayed perceptible surface porosity. The layer thicknesses and the thickness distributions were analysed by surface profileometry. The three different deposition techniques used for film production are compared and described in detail, including the paste production for screen-printing, deposition conditions and post-deposition annealing and sintering processes for all three techniques. The effects of the differences in the film production processes on the film microstructure are discussed. This is important, because differences in microstructure can result in variations in the resistivity versus temperature characteristics.

Keywords: Layer; Ceramic; Sensor; Densification; Porosity; Grain growth; Scanning electron microscopy (SEM); Atomic force microscopy (AFM)

Electron beam induced modification of poly(ethylene terephthalate) films by I.V. Vasiljeva; S.V. Mjakin; A.V. Makarov; A.N. Krasovsky; A.V. Varlamov (pp. 8768-8775).

Electron beam processing of poly(ethylene terephthalate) (PET) films is found to promote significant changes in the melting heat, intrinsic viscosity and polymer film–liquid (water, isooctane and toluene) boundary surface tension. These properties are featured with several maximums depending on the absorbed dose and correlating with the modification of PET surface functionality. Studies using adsorption of acid–base indicators and IR-spectroscopy revealed that the increase of PET surface hydrophilicity is determined by the oxidation of methylene and methyne groups. Electron beam treatment of PET films on the surface of N-vinylpyrrolidone aqueous solution provided graft copolymerization with this comonomer at optimum process parameters (energy 700keV, current 1mA, absorbed dose 50kGy).

Keywords: Poly(ethylene terephthalate); Electron beam processing; Surface modification; Graft copolymerization; N; -Vinylpyrrolidone

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Applied Surface Science (v.252, #24)

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Applied Surface Science (v.252, #24)