High Pressure XAS at the Ti K Edge on Titanate Perovskites
Résumé
X-ray absorption measurements have been performed on BaTi03 and SrTi03 at the Ti K edge under pressure. For BaTi03, the phase transformation to the cubic phase is observed at 2 GPa. In this structure the Ti atoms remain off centre with respect to the oxygen octahedron up to 10 GPa. Above this pressure the Ti atoms are at the centre of the octahedron. For SrTi03, a first transformation is observed above 5 GPa with a modification of the pre-edge features. A second one is observed close to 14 GPa with a complete change of the absorption spectrum.