Advanced Materials Research Vols. 941-944

Abstract: Based on the regularities of motion of the rigid polyurethane rubber ultrasonic vibration assisted grinding, combined with the kinematic analysis of the general theory and experiments. This paper analyses the variation in position, velocity and acceleration during the manufacture of single abrasive grinding with and without ultrasonic vibration. The impact of rigid polyurethane rubber micro V - groove process introduced by the ultrasonic vibration is explored to verify the feasibility of the ultrasonic vibration assisted grinding of micro-precision machining of hard polyurethane rubber material.

Abstract: Polyamide 6 (PA6) gels were prepared by dissolving PA6 powder with relative viscosity 25.85 in formic acid using CaCl₂ as complex agent. Concentration of the polymer was 18 (w/v) %. And then, polyamide 6 (PA6) fibers were obtained through gel-spinning. In this study, the effects of solvent content on fiber structure and properties were investigated. The results showed that with the increasing of solvent content, significant changes occurred in the crystalline structure and thermal property of fibers. The optimum solvent content of fibers with the highest mechanical property in this study was 9.4%.

Abstract: The surface of porous anodic aluminum oxide (AAO) film anodizing in malonic acid, which is characterized by Scanning Electron Microscope (SEM) and ImageJ software. There are disorderly tiny pores or stripes on the first once anodizing surface. Pore diameter, pore density and porosity are decided by the first anodizing process. With anodizing step increased, pore diameter of the membrane decreased. Two-step anodization improves the order of PAA membrane greatly, which is processed on the basic of the ordered array pits at the aluminum that is observed after removing membrane of the one-step anodization. According to the experiments, porous anodic aluminum oxide (PAA) was prepared in 1.0 mol/L malonic acid, its pore diameter increased and porosity decreased with anodizing voltage increased.

Abstract: ZnMn₂O₄ films for resistance random access memory (RRAM) were fabricated on p-Si substrate by magnetron sputtering. The effects of thickness on I-V characteristics, resistance switching behavior and endurance characteristics of ZnMn₂O₄ films were investigated. The ZnMn₂O₄ films with a structure of Ag/ZnMn₂O₄/p-Si exhibit bipolar resistive switching behavior. With the increase of thickness of ZnMn₂O₄ films from 0.83μm to 2.3μm, both the V_ON and the number of stable repetition switching cycle increase, but the R_HRS/R_LRS ratio decrease, which indicated that the ZnMn₂O₄ films with a thickness of 0.83μm has the biggest R_HRS/R_LRS ratio and the lowest V_ON and V_OFF, but the worst endurance characteristics.

Abstract: TiO₂ thin films were deposited by ion beam assisted electron beam evaporation and annealed at 200, 300, 400 and 500 ¡æ in air for one hour. The crystal structures and morphology of the samples were analyzed by an X-ray diffractometer and an atomic force microscope. The transmittance spectra were recorded by a UV-visible spectrophotometer. The results show that both the as-deposited TiO₂ thin film and that one annealed at 200 ¡æ are amorphous. The sample annealed at 300 ¡æ crystallizes in pure brookite phase and is preferentially oriented along the (121) plane. When the annealing temperature rises up to 400 and 500 ¡æ, TiO₂ thin films turn into pure anatase phase. All the samples exhibit high transmittance in the visible region. With the increase of annealing temperature, the transmittance slightly declines and the optical bandgaps also slightly decreases.

Abstract: Using H₂ and Al (CH₃)₃(TMA) as precursor, we investigated the atomic layer deposition mechanism of the metal Al on Si (100) surface by density functional theory. The reaction process comprises two half-reaction depositions: TMA "half-reaction" includes I and II on the H blunt reaction surface; H₂ "half-reaction" includes the subsequent reaction Ⅲ and Ⅳ. In the TMA half reaction process, trimethyl aluminum first molecularly adsorbed in the active site of H*-Si₉H₁₂-H* to form a stable complex in the form of chemical adsorption state. Potential curves show that at 298 K, adsorption energy is -2.26kJ/mol, with respect to the chemical adsorption state, the activation barrier energy is 124.72kJ/mol, and finally the whole exothermic reaction energy is 41.4kJ/mol. After H₂ half reaction, the bond length between Al-Si can be considered equal; two Al-C bonds become relatively stable molecular structure. The adsorption energy is -0.10kJ/mol at 298 K, and the activation barrier energy 189.15kJ/mol. The results show that two half-reaction process mechanism is similar, TMA endothermic reaction needs more energy to be carried out under heating conditions ; endothermic and exothermic reaction energy is basic balance, the activation energy is large, so the reaction is the best using ionized gas to be carried out.

Abstract: Different substrate temperature of CdZnTe films and one with Al-induced crystallization have been investigated by XRD, AFM and UV-spectrophotometry. It was shown that, as the substrate temperature varied from room temperature to 400 °C, improving the substrate temperature helps to enhance the grain size of CdZnTe film, and favours the preferential orientation (111). Moreover, Al-induced crystallization method can effectively reduce the crystallization temperature of the CdZnTe film so that the film can be for high-quality oriented crystallization in a lower temperature. In addition, Al-induced crystallization can make the surface roughness of the film at a small value that facilitates the later application of the film.

Abstract: CdS films were prepared with different sputtering power by radio frequency magnetron sputtering from CdS slices target. The structural and physical properties of CdS films were studied using X-ray diffraction (XRD), atomic force microscopy (AFM), ultraviolet spectrophotometer and Hall effect measurements. The results of structural analysis showed that CdS films are polycrystalline with a cubic structure having (1 1 1) plane and a hexagonal structure having (0 0 2) plane. AFM micrographs show that the grain size increases with the sputtering power increasing. The optical transmission data indicate that all CdS films have high optical transmittance. In Hall Effect measurements, the electrical resistivity of the deposited films are 3.2x10³Ω·cm, 1.5x10⁴Ω and 2.2x10⁴Ω·cm, respectively.

Abstract: The research progress in gasochromics of nano-structured WO₃ film is reviewed. Various fabrication methods of the nano-structured WO₃ film are summarized and compared. Recent gasochromic applications of the nano-structured WO₃ film is introduced. The gasochromic properties were significantly enhanced by applying nanostructures, resulting in faster responses, higher stability and higher optical modulation. A perspective on the development trends in fabrication of nano-structured WO₃ film and devices is also proposed.

Abstract: Zn_0.99-xCo_0.01Al_xO (x=0, 0.01,) thin films have been prepared by a sol-gel method. The structural and optical properties of the samples were investigated. X-ray diffraction and EDX spectrum indicate that Al³⁺ and Co²⁺ substitute for Zn²⁺ without changing the wurtzite structure. With the Al doping,the intensity ratio of the visible to UV emission increases, which is attributed to the increase of O vacancies and Zn interstitials .