TiO_2-SiO_2 composite thin films can be obtained by calcinating the precursor films prepared with spin-coating that comprise organo- titanium compounds and SiO_2 sol. The film sample (Ti: Si = 9: 1) obtained through calcinating at 610 °C for 15 min was studied with SEM, XRD, UV-vis and XPS. The research results show that the film is made up with about 30 nm x 200 nm crystalline particles densely with its thickness of about 200 nm, transmittance rate of visible light is 80% of that of glass substrate and the Ti~(3+)/OH~- ratio on surface of the composite thin film is 1.06. The formation temperature of anatase phase could be elevated mai'kedly by mixing a small quantity of SiO2, which was confirmed by DSC analysis of the gel of film solutions containing different amounts of SiO_2. The studies on photo- catalytic activities of the films revealed that doping certain amount of Fe~(3+) (not in chloride form) is in favor of photo-catalytic reaction. The same holds true in doping Cr~(3+) . In addition, mixing SiO2 can improve the abradability of films, although it adversely affects the photo-catalytic activities.

Key words: TITANIUM OXIDE, SILICON OXIDE, PHOTOCATALYSIS, THERMOLYSIS, SEM, XRD, UV, XPS