Phase Transformation of TiO_2 Detected by UV Resonance Raman Spectroscopy

摘要

Titania has widely attracted attention because of its unique optical and chemical properties including catalytic activity, photocatalysis, sensitivity to humidity and gas, nonlinear optics, photoluminescence and so on. Titania has three crystal structures, anatase, rutile and brookite. It is commonly believed that some properties especially photocatalytic activity of TiO_2 strongly depend on its crystal structures. Many researches showed that anatase phase is the more active phase in photocatalysis. Although bulk properties of titania have been extensively studied in recent years, there is little published information about the surface structure of titania due to the short of characterization technique that can sensitively detect surface structure and phase of TiO_2. So the crystal structure and the phase transformation of TiO_2 are not understood well. Our previous work indicates that the UV Raman spectroscopy is a surface sensitive technique for zirconia because zirconia exhibits strong UV absorption. The UV Raman spectra together with visible Raman spectra and XRD patterns indicate that the phase transformation of zirconia and doped zirconia starts from the surface region of the particle and then extends into the bulk. In this paper, the phase transformation and structure of TiO_2 prepared by different methods are detected by UV Raman and Visible Raman spectroscopy.