Anatase to rutile transformation in sol-gel titania by modification of precursor

The effect of pH on the formation of high temperature phases in titanium oxide, derived by hydrolysis of modified titanium isopropoxide has been reported. The anatase to rutile phase transformation is delayed in the case of acetic acid modified gel precursor at pH 3 and 4, showing the presence of anatase phase even at 1000 degrees C. On the other hand, in the sample precursor prepared at pH 6, anatase to rutile transformation is complete at 800 degrees C, under identical conditions of heat treatment. The transformation has been followed by thermal analysis and X-ray powder diffraction data. Impedance spectroscopy has been attempted as a useful and effective tool in identifying the anatase and rutile phases as well as transformation temperatures. (C) 1998 Elsevier Science Ltd. All rights reserved.