No abstract

Pure titania pulp containing amorphous titania was heated at different temperatures and times. Above 650uC anatase phase was evolved and between 900 and 1000uC, anatase-rutile transformation occurred. The anatase-rutile transformation in TiO 2 in the presence of different transition metal oxides, namely Fe 2 O 3 , Cr 2 O 3 , NiO, CuO and MnO 2 under argon and hydrogen atmospheres was investigated. The different phases of TiO 2 were determined using powder X-ray diffraction (XRD). The anatase-rutile transformation temperature was found to be lowered in the presence of transition metal oxides. The transformation temperature was found to vary much in argon and hydrogen atmospheres compared to air in the presence of the metal oxides. Also the method of preparation of metal oxide doped TiO 2 influences rutilation. Other methods such as chemical analysis, surface area measurements and crystallite size calculation were used for the characterisation of the samples. The surface area of heated samples was found to be decreased while crystallite size increased due to rutilation on heating. The samples were also observed under a scanning electron microscope to characterise the microstructural changes associated with each thermal treatment and atmosphere. The morphology of doped titania changes much on heating due to phase modification. The atmosphere of heating also has important effect on deciding the morphology of rutilated titania.