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.