IOSR-JAP   Volume-5 ~ Issue-1 ~ Nov–Dec 2013

Abstract: Thermal oxidation of copper has been restudied to control the formation of photovoltaic active cupric oxide (CuO) phase against the cuprous oxide (Cu2O) phase. It has been established that the thermal oxidation of copper is governed by the outward lattice diffusion and grain boundary diffusion of copper ions at the interface. The lattice diffusion favors the formation of Cu2O phase whereas grain boundary diffusion favors the formation of CuO phase. In the present work, a fine copper powder is taken as starting material for thermal oxidation to increase the grain boundary diffusion and to study its on phase formation. Further, to suppress the grain boundary diffusion the starting material is chemically passivated with diethylenetriamine and olelamine to chameically passivated the surface defects. Thermal oxidation of these pre-treated materials is carried out in open air at temperature 500 oC and 700 oC to study the phase formation. The resulting materials are characterized by x-ray diffraction and scanning electron microscopy. These studies clearly confirm that grain boundary diffusion or defect mediated diffusion due to small particle size and more surface atoms of copper favor the formation of CuO at low temperature in case of pure copper, whereas the chemical passivation and high temperature heating favours the formation of Cu2O phase and hence the resulting material is biphasic. Hence, the present study is useful information in controlling the phase formation of copper oxide to obtain more photoactive material that is CuO.

Keywords: Thermal Oxidation, copper, lattice diffusion, grain boundary diffusion, CuO and CuO2 phases.

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Abstract: In fact, the vertical position of Michelson-Morley experiment is not the only possible explanation for the new phenomenon of the vertical Aether flow into any mass or any fundamental building block. This paper shows, for the first time, that the cosmic blue shift due to a gravitational field is a direct consequence of the vertical Aether flow into any mass. The vertical Aether speeds of different stellar objects have been given, which suggest reclassifying the categories of black holes. To confirm the theory presented, new formulas for Doppler Effect in a gravitational field and its correlation with the time dilation, as derived from the General Relativity, has also been derived. The theoretical expressions corresponding to the two experimental results have been given. Also, a new prediction has been proposed, for the first time, to confirm the theories presented in this paper.

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Abstract: CdO-Mn3O4 nanocomposite has been prepared by a simple solvothermal method using a domestic microwave oven. Cadmium acetate, manganese acetate and urea were used as the precursors and ethylene glycol as the solvent. The as-prepared sample was annealed for 1 hour in each case at different temperatures, viz. 100, 200 and 300°C. The as-prepared and annealed samples were characterized by X-ray diffraction and scanning electron microscopic analyses. Results indicate that annealing at 300°C is required to get the sample with high phase purity and homogeneity. The present study indicates that the method adopted can be considered as an economical and scalable one to prepare the proposed nanocomposite with reduced size, phase purity and homogeneity.

Keywords: Nanoparticles, Nanocomposites, Solvothermal method, X-ray diffraction, SEM analysis.

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Abstract: CoxZn1-xS (x=0-0.1) polycrystalline semiconductor compounds were synthesised by co-precipitation method and were characterised by X-ray diffraction (XRD), UV-absorption, EDAX, SEM and Fourier Transform Infrared (FTIR) studies. XRD studies have shown that these powders have polycrystalline nature with a gradual variation from hexagonal to cubic structure while x changing from 0 to 0.1. UV-abosrption studies revealed that the band gap of CoxZn1-xS (x=0-0.1) samples decreased with increase in cobalt concentration, owing to the enhancement of sp-d exchange interactions and typical d-d transitions. Chemical homogeneity and surface morphology studies were carried out by using EDAX and SEM. Fourier Transform Infrared (FTIR) spectroscopy also revealed that cobalt is induced into the lattice replacing Zinc.

Keywords: Polycrystalline Semiconductor CoxZn1-xS, X-ray Diffraction, EDAX, SEM, Optical Properties.

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