Advanced Materials Research Vols. 299-300

Abstract: In this paper, the structure, electrical and optical properties and stabilities of Ag doped p-type ZnO thin films, prepared by electrostatic-enhanced ultrasonic spray pyrolysis were investigated. XRD and Hall data analyses indicated that the resistivity of 4at. % Ag doped p-type ZnO was low, without Ag₂O phase separation. The optical transmission spectra illustrated that optical band gaps decreases with the gradual increase of Ag dopant. Moreover, ZnO: Ag films placed for 10 days still showed p-type, but the optical transmittance decreased, suggesting that Ag_Zn in the ZnO: Ag thin films captured electrons to generate Ag_i, which reunited to be Ag nano-particles and decreased the optical transmittance of ZnO: Ag.

Abstract: The influence of different broaching rate, the training of thermo-mechanical cycle and Electro-pulse Modification (EPM) on the shape memory effect of the FeMnSiCr alloy was investigated. The recovery pulling force can be realized as high as 22850N after EPM treatment. The Fe-based shape memory alloy (SMA) pipe joint can meet the requirement of engineering application.

Abstract: Single crystalline ZnO thin films have been deposited on epi-GaN/sapphire (0001) substrates by the metalorganic chemical vapour deposition (MOCVD) method. The structural and optical properties of the ZnO films were investigated in detail. The film prepared at 600°C was epitaxial single crystalline with the wurtzite structure of pure ZnO and a single orientation of (0002) direction. High-resolution transmission electron microscopy was used to investigate the interface area, and a clear orientation relationship of ZnO (0001) || GaN (0001) and ZnO [] || GaN [] was obtained. The average transmittance for the samples in the visible range was over 75%.

Abstract: A series of the magnesium apatite coatings according to (Ca_10-xMg_x)(PO₄)₆(OH)₂, where x = 0 to 2, was synthesized through a sol-gel dip-coating method. The roughness of the magnesium coatings increased as more magnesium incorporated into the coatings. The mechanical properties of the coatings were analyzed with Nanoindentor. The incorporation of magnesium decreased the hardness and the Young’s modulus of the coating. The X-ray Photoelectron Spectroscopy (XPS) analysis revealed that only part of magnesium was incorporated into the apatite structure while the rest existed in the form of MgO in the coating.

Abstract: A novel calix[4]arene chromophore 1 was synthesized by introduction of two D-π-A units (4-nitrophenyl)azophenyloxy groups) on the lower rim of calix[4]arene. The measurement results of hyper-Rayleigh scattering (HRS) and UV-vis spectra show that the static first molecular hyperpolarizability of the chromophore 1 is more than two times that of the corresponding mono-D-π-A unit reference compound 4-(4-nitrophenylazo)phenol 2, without causing red-shift of absorption band.

Abstract: Aluminum oxide film doped with Ce³⁺ has been deposited by the medium frequency reactive magnetron sputtering technique. The photoluminescence emission from these films show peaks at range of 374-405 nm. The relative intensity of these peaks is strongly dependent on the amount of Ce incorporated in the films. The presence of Ce³⁺ as well as the stoichiometry of these films has been determined by energy dispersive x-ray spectroscope (EDS) measurements. It is proposed that the light emission observed generated by luminescent center associated with cerium chloride molecular rather than to atomic cerium impurities. The reason for a dominance of the lower energy transition as the amount of Ce³⁺ in the oxide films is increased is that the energy difference of 4f¹and 5d¹ decreases, with the increase of the Ce³⁺ concentration. These luminescent films are potentially good candidates for photonics applications.

Abstract: By designing different formulations of composites and adopting optimized technology including extrusion and molding, the different composites with various content microcapsules were prepared. The results of the tensile tests show that with the increasing content of self-healing microcapsules in the glass fiber reinforced nylon composites, the mechanical properties of the composites will change, i.e. tensile strength, elastic modulus will decrease. But there is little effect on the mechanical properties of the composite gears if the content of self-healing microcapsules is less than 3.5%, and the technology of self-healing microcapsules used in the polymer composite gear is feasible.

Abstract: The oxidation behavior of the Ni-base superalloy was studied at 850 °C and 950 °C for 100 h in air using XRD and SEM/EDAX. The mass gain of the alloy at 850 °C was found to be lower than that of the alloy at 950 °C. The oxidation rate was determined by temperatures. The alloy obeyed a subparabolic rate law during oxidation at 850 °C and 950 °C. The scale consisted of an outer porous layer of TiO_2, a middle continuous layer of Cr₂O₃, and inner Al₂O₃.

Abstract: A simple injection molding process was proposed for manufacturing polyethylene (PE) biofilm carrier composited with various powder additives including hydroxyapatite (HAP), starch, bagasse, activated carbon(AC) and magnetic powder(MP) as slow-released nutrients in wastewater biological treatment. The powders were also responsible for improving the hydrophilicity and biomass affinity of the carrier. Pre-attachment between powders and PE particle may achieve great improvement in flow ability of particle-powder mixture during injection molding process. The slow release rate of nutrients (mainly water-soluble starch) from the modified carrier to wastewater can be controlled by the amount of bagasse and activated carbon supplemented in the carrier. The contact angle of a water droplet on the polyethylene surface decreased from 80° to 59° after modification, and the period of biofilm formation on the modified carrier with acclimated sludge reduced from 7 days (on PE carrier without additives) to 4 days. The amount of attached biomass on the modified carrier was also found about twice as that on the common PE carrier. The strength performance test demonstrated the capability of long-term operation for the modified carrier in practical application.

Abstract: The NO₂-sensing properties of the ZnO films prepared by EUSP were investigated. Effect of substrate temperature on the NO₂-sensing properties of ZnO films showed that the powder-like ZnO film deposited at 550°C was more sensitive to NO₂, and the film illustrated good response-restoration property. Besides, the influence of doping amount on the NO₂-sensing properties of the ZnO films at 260°C showed that the ZnO:Al film with the Al content of 0.4mol% presented the best sensitivity, and the ZnO: 3mol % Ag exhibited the highest NO2 sensitivity. The dynamic response tests indicated that the ZnO: Al film was of the highest sensitivity to NO₂, and the sensitivity of ZnO: Ag film was lowest.