Phaser transformation in sol-gel titania containing silica

摘要

Titanium dioxide containing 50-10/100 silica has been prepared by the co-hydrolysis of titanium isorpoxide at pH 4 in presence of TEOS in different solvents such as methoanol, thanol and water. The resultant gelas have been annexed by BET surface area measurements and thermal analysis. Addition of 5/100 silica to TiO_2 increases initial surface area of 89 to 188 m~2/g. As the amount of silica is further increased to 10/100, the surface area is further increased to 203 m~2/g while the corresponding sample in methanol had 217 m~2/g. Addition of silica has further resulted in considerable increase of anatase-rutile transformation temperature >800degC. Addition of methanol and ethanol to titania-solica systems enhances the formation of rutile phase. This phase transformation has be followed by X-ray powder diffraction data and further, through impedance measurements on the precursor gel pellets heated to various temperatures and the later has been presented as a very simple and convenient tool to study phase transformation in titania ceramics.