Author(s): Zhaolin Liu, Bing Guo, Liang Hong, Huixin Jiang
A mixed oxide consisting of TiO as the major phase and CeO (0<<0.5) as the dopant phase was prepared via the sol-gel reaction of Ti(-OCH) in an aqueous solution of Ce(NO). The resulting oxide powders with different CeO contents were all composed of nano-sized spheres. The CeO phase was identified to have retarding effect on the phase transition from anatase TiO to rutile TiO at calcinations temperature as high as 800 °C, which would otherwise be a thorough conversion. The CeO–TiOpowders could apparently shift the UV-absorption band of TiO toward visible range, and there was an optimal CeO content in association with the maximum absorbance. This effect is interpreted as the existence of an n-type impurity band, due to the substitution of Ti for Ce at the interface between the two oxides, in the gap of TiO. According to X-ray photoelectron spectroscopy (XPS) investigation, the Ti element mainly existed as the chemical state of Ti and the Ce oxide doping did not affect the peak position of Ti 2p. The Ce 3d spectrum of CeO-doped TiO sample basically denotes a mixture of Ce oxidation states giving rise to a myriad of peaks.
Research & Reviews: Journal of Material Sciences