Effect of precursor sol's aging on properties of nanostructured thin films with coexistent CeO2 and CeTi2O6 phases

Thin films constituting CeO2 and CeTi2O6 phases have been deposited using a solution of cerium chloride heptahydrate and titanium propoxide in ethanol. The effect of sol's aging on different properties of the films has been discussed. X-ray diffraction and transmission electron microscopic investigations have shown the coexistence of CeO2 and CeTi2O6 phases in these films. Fourier transform infrared studies have affirmed increased bond strength of Ti-O network in the films as a function of sol's aging. Optical transmittance is observed to be higher in the aged sol films. Scanning electron microscopy study has illustrated that the aged sol leads to compact films with lesser porosity. Photoluminescence (PL) intensity in the films has shown dependence on sol's aging with the films deposited from the aged sol exhibiting low PL activity. The decomposition of eosin (yellow) under UV-visible light irradiation in the presence of CeO2-CeTi2O6 films shows the presence of photoactivity in these films. Compared to TiO2 films, the CeO2-CeTi2O6 films have exhibited better photocatalytic response. Electrochemical investigations have revealed superior response in the aged sol films. Ion storage capacity and diffusion coefficient for Li ions in the aged sol films is measured to be greater. The higher transmission modulation of WO3 film configured with the aged sol CeO2-CeTi2O6 film demonstrates the potential of the latter films as a promising counter electrode in electrochromic windows.