Raman microprobe study of nanophase TiO2 and oxidation-induced spectral changes

Abstract

A Raman microprobe study of as-compacted nanophase TiO2 was carried out to investigate the spatial inhomogeneity of its anatase and rutile phases. Also, changes in the observed Raman spectra (line shifts and broadening) were investigated as a function of annealing at temperatures up to 600°C in argon or air. Microscopic phase inhomogeneity is observed and Raman spectral changes are shown to result from inhomogeneous oxygen deficiency in the nanophase TiO2. The line positions corresponding to the Raman active Eg modes in both anatase and rutile are found to be sensitive to this oxygen deficiency and are potential quantitative indicators of such deviations from stoichiometry.