Characterization of TiO2 powders and thin films prepared by non-aqueous sol–gel techniques

Stable TiO2 sols were prepared using two nonaqueous sol–gel processes with titanium n-butoxide and titanium isopropoxide, respectively. Crystallization and phase transitions of powders and thin films were studied by ex situ and in situ X-ray diffraction. For both methods, TiO2 began to crystallize around 320 C in air. Using helium instead of air during heat treatment slowed down the crystallization and substoichiometric powders were formed. TiO2 thin films were obtained by spin coating. The morphology of the films was evaluated using scanning electron microscopy. The films were homogeneous and transparent in the visible range. The effect of the heating atmosphere and the type of substrate was investigated.