Phase transitions and Raman spectra of anatase and rutile at high pressures and room temperature

Abstract

Anatase transforms to a columbite-type TiO2 at 54±2kbar, and the transition is nearly instantaneous but irreversible. Rutile transforms to the same high-pressure phase, starting near 100kbar, but the transition is sluggish and irreversible. The pressure dependences of the various Raman bands of anatase and rutile observed in the present study are in good agreement with those published in the literature. New data of the pressure dependences of the various Raman bands of columbite-type TiO2 are reported here. Each of these phases has one very weak Raman band and its wavenumber decreases linearly with increasing pressure. These weak bands appear to vanish (or are undetectable) at high pressures in anatase and the columbite-type TiO2. -from Authors Show more