Pressure-induced disappearance of the local rhombohedral distortion inJ. P. Itié1, 2, B. Couzinet1, A. Polian1, A. M. Flank2 and P. Lagarde2
1 Physique des Milieux Denses, IMPMC, CNRS UMR 7590, Université P. et M. Curie 140 Rue de Lourmel, 75015 Paris, France
2 Synchrotron SOLEIL, CNRS UR1 - L'Orme des Merisiers St Aubin BP 48, 91192 Gif-sur-Yvette Cedex, France
received 27 January 2006; accepted in final form 21 March 2006
published online 14 April 2006
has been studied by X-ray absorption spectroscopy at the Ti K edge up to in a diamond anvil cell at room temperature. The pre-edge features observed at the Ti K edge are sensitive to the pressure. It is shown that the high-pressure cubic phase obtained above is similar to the high-temperature one, with titanium out of the centre of the oxygen octahedron. Between 2 and the intensity of the pre-edge features decreases indicating that the Ti atom is moving toward the centre of the oxygen octahedron. Above , the features do not change anymore, showing that the Ti atom is at the centre of the oxygen octahedron. No correlation between the Ti atom position and the Raman activity under pressure is observed.
81.40.Vw - Pressure treatment.
78.70.Dm - X-ray absorption spectra.
77.84.-s - Dielectric, piezoelectric, ferroelectric, and antiferroelectric materials.
© EDP Sciences 2006