RAMAN-SPECTROSCOPY AT MANTLE PRESSURE AND TEMPERATURE CONDITIONS EXPERIMENTAL SET-UP AND THE EXAMPLE OF CATIO3 PEROVSKITE

We present a new experimental set-up for studying minerals by Raman spectroscopy in-situ at simultaneously high pressures (up to 35 GPa) and high temperatures (up to 2000 K). High pressures are generated with a diamond anvil cell and local sample heating is obtained by focussing the beam of a CO2 laser on the pressurized sample through a type IIa diamond. The Raman spectrum and the thermal emission of the sample are collected on the same 2 mum-sized heated area, whereas the pressure can be measured simultaneously anywhere in the pressure chamber. Temperature in the central part of the heated spot is estimated from the thermal emission curves. Pressures are obtained by the classical fluorescence technique. Raman spectra of CaTiO3 perovskite, analogue of MgSiO3-perovskite, are presented at temperatures up to 1700 K at a pressure of 12 GPa. These data are compared with high temperature Raman data at ambient pressure. The spectral changes upon heating observed in both series of experiments are discussed.