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

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 (<= 800 degrees C). 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 N-2 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 (r=100), resulting in precipitated crystalline powders exhibiting brookite and anatase, which begin to transform to rutile below 500 degrees C. The powders precipitated in a predominantly organic medium (r=6) underwent partial hydrolysis, were highly porous and exhibited an amorphous structure, with the crystallisation of anatase occurring at similar to 300 degrees C and the transformation to rutile beginning at 500-600 degrees C.