An alternative sol-gel route for the preparation of thin films in CeO2-TiO2 binary system

Thin films of titania-ceria have been prepared via sol-gel processing by employing titanium and cerium chloride compounds in highly acidic conditions for the precursor sol. This sol-gel route allows obtaining titania-ceria and cerium titanate films, CeTi₂O₆, after thermal treatment in air. The films exhibit a high optical transparency which is modulated by controlling the composition and the thermal treatment. The materials have been characterized by X-ray diffraction, UV-visible spectroscopy, ellipsometric spectroscopy and atomic force microscopy. The titania-ceria films show, as a function of the composition, the formation of different phases after thermal treatment in air at 800 °C. In particular, with the composition Ce25-Ti75 we have obtained a pure cerium titanate phase, CeTi₂O₆, which can be formed only in a very strict range of compositions.