Advanced Materials Research Vols. 194-196

Abstract: In this work, polyaniline co-doped with (IS)-(+)-10-camphorsulfonic acid (D-CSA) and Ni²⁺ was synthesized via in situ polymerization. The structure, conductivity and electromagnetic parameters of the resulting polyaniline were characterized by FTIR, SZ82 digital multimeter and AV3618 network analyzer. The conductivity of polyaniline at room temperature increases with increasing of Ni²⁺ loading. Moreover, the resulting polyaniline co-doped with Ni²⁺ displays obvious magnetic loss at the microwave frequency. So, we suppose that this conducting polymer can be used as microwave absorbing material with wide-range and good effect.

Abstract: ZnO: In (IZO, 10wt % In₂O₃) and ZnO: Al (AZO, 1wt % Al₂O₃) films were deposited on Corning glass substrates by RF magnetron sputtering. The samples were either prepared on unheated substrates and post annealed in N₂ at different temperatures, or prepared at elevated temperatures. Electrical, optical and structural properties were investigated as a function of deposition temperature and annealing temperature. Increasing the substrate heater temperature would lead to a decline in the electrical conductivity of IZO films, while AZO films showed unchanged performance in the substrate heater temperature range of 150 - 300°C. Post annealing appears to be an effective way to improve the electrical properties of both IZO and AZO films without sacrificing transparency. In this work, AZO films have higher conductivity and light transmission than IZO films.

Abstract: Bonded structure are commonly of three types, purely adhesive bonded, weld-bonded and adhesive/mechanical structures. Peel and overlapped joints are commonly used in the development of bonded structures. T-Peel bonded joint has week tensile strength load compared to double-overlap bonded joint. The present work aimed to predicting the strength of weld-bonded T-peel joint with single overlap weld-bond support plate using finite-element method. For comparison purposes, weld-bond T-peel joint without support is included in this study. It was found the peak stress is concentrated towards the inner far end of T-peel mid-layer of adhesive and through weld-nugget center. The introduction of single overlap weld-bond support for T-peel joint strengthen the joint by 500%.

Abstract: The nickel based Colmonoy 5 alloy powder was deposited on 316 L (N) austenitic stainless steel substrate. In order to examine the effects of aging treatment on the wear behavior of a nickel based hardfacing alloy, the as-deposited coating was aged at 580°C for 5000h in ambient atmosphere. Coating microstructures were characterised by scanning and transmission electron microscopy. Sliding tests were conducted under self mated condition at room temperature and 550°C using a pin-on disc type apparatus. The wear loss of the aged coating was found to be higher than that of the as deposited coating. The coarse grained structure with carbide (Cr₂₃C₆) precipitation in the aged coating would account for the higher sliding wear loss. However, the aged coating, with reduced hardness exhibits similar wear behavior of as deposited coating during sliding at 550°C.

Abstract: The Ni-Mn-Fe-Ga shape memory alloy thin film was deposited onto silicon substrates by using radio-frequency (R.F.) magnetron sputtering technique. Chemical composition, surface morphology and crystallographic structure were systematically investigated by means of X-ray fluorescence (XRF), atomic force microscope (AFM) and X-ray diffraction (XRD). The experimental results show that the magnetron sputtering process has remarkable influence on the chemical compositions and surface characteristics of Ni-Mn-Fe-Ga alloy thin films. As the sputtering power ranging between 245W and 405W, Ni content of the thin films decreases with the sputtering power increasing, whereas Mn and Fe contents increase with increasing the sputtering power and Ga content almost keep a constant. The surface roughness and the average particle size of thin films increase with the increase of Ar working pressure and sputtering power. The film deposited at room temperature has a cubic L2₁ structure.

Abstract: TiO₂ thin films were successfully deposited on microscope glass slides by means of d.c. sputtering method using Ar and O₂ as the working gases. Then Ce ions at nominal doses of 2×10 ¹⁶ions/cm² and 2×10¹⁷ions/cm² were implanted into the TiO₂ thin films to observe the effects of implantation on the photocatalytic activities of the TiO₂ thin films. The photocatalytic activities of the samples were evaluated by the photodegradation of Rhodamine B solution. It was found that Ce ions implantation decreased the photocatalytic activities of the TiO₂ thin films and the results were discussed.

Abstract: Hydrophobic transparent hard sol–gel nano-composite films were successfully prepared by means of a two-step acid-catalyzed method and the sol-gel process using tetraethoxysliane (TEOS) and aluminium isopropoxide Al(C₃H₇O)₃ as precursors, methyltriethoxysilane (MTES) and cetyltrimethylammonium bromide (CTAB) as chemical modifier and surfactant, respectively. The infrared spectra of the films thus obtained indicated that they become hydrophobic with the introduction of the methyl groups. Contact angle values for the nano-composite films prepared are greater than 125°C. The Optical transmittance spectra and the hardness test measurement results showed that the nano-composite films are transparent and hard.

Abstract: In this study high quality of Al doped ZnO (ZAO) thin films were prepared by RF magnetron sputtering on glass substrates at room temperature in order to study the thickness effect upon their structure, electrical and optical properties. XRD results show that the films are polycrystalline and with strongly preferred (002) orientation perpendicular to substrate surface whatever the thickness is. The crystallite size was calculated by Williamson-Hall method, while it increases as the film thickness increased. The lattice stress is mainly caused by the growth process. Hall measurements revealed electrical parameter very dependent upon thickness when the thickness of ZAO film is lower than 700 nm. The resistivity decreased and the carrier concentration and Hall mobility increases as the film thickness increased. When film thickness becomes larger, only a little change in the above properties was observed. All the films have high transmittance above 90% in visible range. Red shift of the absorption edge was observed as thickness increased. The optical energy bandgap decreased from 3.41eV to 3.30 eV with the increase of film thickness.

Abstract: Different thickness of CdZnTe films were deposited onto glass substrates by RF magnetron sputtering from Cd_0.9Zn_0.1Te crystals target. Their structural characteristics were studied by X-ray diffraction (XRD). The XRD experiments showed that the films are polycrystalline and have a zinc-blende (cubic) structure. The crystallite size and micro-strain were calculated. It is observed that the crystallite size increases and micro-strain decreases with the film thickness. The optical measurements showed that the average transmittance of all the samples have is less than 50% in the visible range. The possible optical transition in these films is found to be allowed direct transition with energy gap increase from 1.53 to 1.75 eV. For the electrical properties, the sheet resistivity decreased from 2.582×10⁸ to3.069×10⁷ Ohm/sq when the thickness increased from 307 to 823 nm; while the carrier concentration seems to be less affected by the film thickness. This behaviour in electrical properties was explained by the crystallinity and the grain size evolution.

Abstract: C₆₀ thin films were deposited on Si substrates at different evaporation temperatures using the thermal evaporation method. In this paper, an extensive study of morphology and crystallinity of the films was presented by atomic force microscopy (AFM), low angle X-ray diffraction (LA-XRD) and UV-vis spectrophotometer. It is found that a good crystalline quality along a (333) preferred orientation was observed at the 450°C evaporation temperature and an ordered sequence of fcc structure was evaluated. The 2.24eV optical energy bandgag of C₆₀ thin film corresponding to h_u→ t_1u transition between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels was also extracted.