Single and mixed phase TiO2 powders prepared by excess hydrolysis of titanium alkoxide

Abstract

To investigate the excess hydrolysis of titanium alkoxides, TiO2 powders were fabricated from titanium tetraisopropoxide using 6 : 1 and 100 : 1 H2O/Ti (r) ratios. The powders were dried and fired at a range of temperatures ((800uC). Hydroxylation and organic content in powders were characterised using attenuated total reflectance Fourier transform infrared spectroscopy (FTIR), laser Raman microspectroscopy and elemental microanalysis; surface area and pore size distribution were evaluated using N2 gas adsorption; phase composition was analysed using Xray diffraction (XRD) and laser Raman microspectroscopy; and crystallite size was evaluated by XRD, TEM and SEM. Results showed near complete hydrolysis in a predominantly aqueous medium (r5100), resulting in precipitated crystalline powders exhibiting brookite and anatase, which begin to transform to rutile below 500uC. The powders precipitated in a predominantly organic medium (r56) underwent partial hydrolysis, were highly porous and exhibited an amorphous structure, with the crystallisation of anatase occurring at y300uC and the transformation to rutile beginning at 500–600uC.