Preparation of brookite phase TiO2 colloidal sol for thin film coating

Transparent TiO2 sols were hydro-thermally prepared with heating Ti precursor solutions, from Ti hydroxides obtained with neutralizing aqueous TiOCl2 solutions having various concentrations of NaCl by aqueous NaOH solution, in the autoclave. The crystalline, microstructural and optical properties of the particles from TiO2 sols by freeze-drying or coating were investigated using XRD, BET, SEM, and UV–vis spectroscopy. With controlling the internal pressure in the autoclave by capturing Na ions in the lattice of Ti hydroxide how to prepare TiO2 sol containing composite of anatase and brookite phases was discussed.