OPTICAL AND ELECTROCHEMICAL PROPERTIES OF CEO2 AND CEO2-TIO2 COATINGS

Thin solid films of CeO2 and mixed CeO2-TiO2 were prepared by the sol- gel route via the dip-coating technique. Particulate sols of ceria wer e made from inorganic ((NH4)2Ce(NO3)6) precursor which were used for p reparation of CeO2 thin solid films while CeO2-TiO2 coatings have been made by using mixed organic-inorganic (Ti(OiPr)4 and CeCl3.7H2O) prec ursors. The solar transmission values (T(s)) of both coatings are in t he range 0.6-0.8 and depend on coating thickness. Cyclic voltammetric (CV) measurements show that the CeO2/LiOH system exhibits higher overa ll electrochemical reversibility when compared to the CeO2-TiO2/LiOH s ystem. The CeO2/LiOH system is also less sensitive with regard to the coating thickness. Coulometric measurements show that CeO2 exhibits a larger storage capability which was determined as a function of the co ating thickness. ''In situ'' UV-VIS spectroelectrochemical measurement s which have been performed on CeO2 and CeO2-TiO2 coatings revealed th at both types of samples exhibit electrochromic effect in the spectral range 500 < lambda < 330 nm but remain unchanged in the visible spect ral range.