Showing papers by "Ganesan Ravi published in 2010"

Effect of deposition potential on the physical properties of electrodeposited CuO thin films

Abstract: Semiconducting cupric oxide (CuO) thin films were prepared onto ITO substrates from alkaline medium using electrodeposition technique. CuO thin films were characterized by stylus profilometer, scanning electron microscopy (SEM), X-ray diffraction (XRD) and optical absorption techniques. X-ray diffraction study shows that the electrodeposited CuO thin films are polycrystalline in nature with face centred cubic structure prepared under various deposition potentials. X-ray diffraction studies also reveal that the films exhibit preferential orientation along a (111) plane with crystallite size between 40 and 43 nm. Micro structural properties of films such as lattice parameter, grain size, dislocation density and micro strain were calculated from predominant (111) diffraction lines. The optical constants (refractive index (n) and extinction coefficient (k)) of CuO thin films were evaluated using optical studies. SEM studies show that the grain sizes of CuO thin films vary between 100 and 150 nm and also morphologies revealed that the electrodeposited CuO exhibits uniformity in size and shape. The effect of deposition potential on the physical properties like structure, morphology, microstructure and optical properties of the CuO thin films are studied.

On the study of pH effects in the microwave enhanced rapid synthesis of nano-ZnO

Abstract: The rapid synthesis of ZnO nanostructures by microwave treatment of aqueous solutions of different pH values is reported for the first time. Microwave in various wattages was used as the source of heating or energy feeding the aqueous precursors. The pH of the zinc metal source was altered by a suitable amount of mineralisers. The considered pH values are 8, 10, 12 and 13.5. Microwave dielectric heating is dependent on the ability of the material to absorb microwave. This is responsible for molecular friction and dielectric loss, which as a result produce internal heating of the dielectric medium, in this case the solution. In typical microwave assisted synthesis, the total exposure to the microwave treatment was near about 25 to 35 minutes. The ZnO nanostructures obtained were studied by XRD, SEM and TEM characterisations. From the XRD pattern and the full width half maximum of the dominant reflections, microstructural parameters of the nanostructures are calculated and compared for the different pH values. Flower petal like flakes and hexagonal nanorods are formed for the lower and higher pH solutions, respectively. From the SEM images, the size distributions for the pH 12 and 13.5 cases are compared by drawing a histogram.