Abstract
Porous TiO2 having high humidity sensitive properties was prepared by two different methods. Porous TiO2 samples were synthesized by rapid quenching of phase separated TiO2-SiO2 melts and subsequent selective leaching of SiO2 matrix. TiO2 thin film samples were prepared by RF magnetron sputtering using TiO2-SiO2 ceramic target and subsequent selective leaching of SiO2 component. In the former samples, a phase separation texture was obtained by spinodal decomposition with 50 mass% TiO2, while the texture changed to a binodal type at 60 mass% composition. The electrical resistance of these samples changed only slightly even changing relative humidity. In the TiO2 thin films, the electric resistance changed clearly depending to relative humidity change. Since the tendency of electrical resistance change varied at about 50%RH, the conducting mechanism is considered to be different between low and high humidity regions.
