12-15 July 2011
Saint George Hotel
Africa/Johannesburg timezone
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DRS, XRD and SEM studies of the effects of metal dopants (Pt, Au and Pd) on the structural and optical properties of TiO2.

Presented by Mr. Jacob Ramodika MOLOANTOA on 13 Jul 2011 from 17:00 to 19:00
Type: Poster Presentation
Session: Poster1
Track: Track A - Condensed Matter Physics and Material Science


<p>Titania is a cheap and nontoxic polymorphic material of current interest for a variety of technological applications like in gas sensing and photovoltaic cells. Generally, TiO2, with a band gap of 3.2 eV, can only be excited by a small UV fraction of solar light, which accounts for only 3-5% of the solar energy. Various strategies have been pursued including doping with metallic elements (e.g. Fe) or nonmetallic elements (e.g. N) with the aim of shifting the absorption into the visible range. In the present work TiO2 was doped with platinum (Pt), palladium (Pd) and gold (Au) at doping levels of 5% weight, following the standard sol-gel methods. Structural characterization was carried out using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Optical properties were studied using the Diffuse Reflectance Spectroscopy (DRS). The results of the lattice parameter calculations from the XRD patterns of metal loaded TiO2 are almost the same as for the undoped. Doping with Pt and Pd resulted in a lower anatase to rutile phase transformation temperature while doping with Au did not affect the transformation temperature. SEM micrographs show that the surface contains irregular shaped particles which are the aggregation of tiny crystals for lower temperatures. At higher temperatures (900 °C), we observe spheroids of metallic nanocrystals on the surface of TiO2.The reflectance spectra of the metal loaded TiO2 reveal substantial reduction in reflection (i.e. they show enhanced absorption)from 400nm to the entire visible region.

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Room: Asteria

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