Temperature dependence of the titanium oxide sols precipitation kinetics in the sol-gel process

We report on observations of the temperature dependence (T = 5-40 degreesC) of the titanium oxide sols precipitation kinetics in the sol-gel process using Ti(OPri)(4) as a metal organic precursor. The nanometric sol particles are produced in the sol-gel reactor with rapid reagent mixing and temperature and atmosphere control. Precipitation kinetics was followed in situ by the light scattering method using an optical fibre probe. From these measurements the activation energy E-a = 0.33 +/- 0.02 eV has been obtained and assigned to the secondary hydrolysis-condensation reactions between surface Ti-OPri groups. Careful analysis of experimental data allows concluding about a decrease of the fractal dimension D-f of the precipitate with an increase of the temperature, which provides D-f = 1 at 35 degreesC. (C) 2004 Elsevier B.V. All rights reserved.