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The obtaining of titanium dioxide nanocrystalline powders

The paper describes the obtaining of TiO2 nanocrystalline powders by sol-gel method. TiO2 nanocrystalline powder was obtained by hydrolysis of TiCl3 precursors in alkaline medium. The influence of bath condition (static or magnetic stirring), treatment with concentrated H2O2 and thermal treatment at 500 o C for one hour was investigated. In the absence of H2O2 a crystalline phase containing both anatase and rutile has been obtained, while in the case of oxidized sample anatase alone has been identified. Structural analyses were made using X ray diffraction. Optical properties have been determined using UV-VIS spectroscopy. The band gap of the obtained powder has been calculated. Thermal treatment and H2O2 oxidation leads to the red shift of the band gap energy for all samples. The photoresponse of all samples moved from ultraviolet to visible region. The obtained powder can be embedded in a polymer matrix, in order to obtain photoactive composite materials.