In Situ High-Pressure Experiment Using the KMA Equipped with Sintered Diamond Anvils

Abstract

  Pressure range of in situ x-ray observation has been extended very close to 100 GPa, by interfacing the Kawai-type multi-anvil apparatus (KMA) equipped with sintered diamond anvils with the synchrotron radiation at SPring-8. High-pressure phase equilibria in Fe₂O₃ and MgGeO₃ are summarized. Isostructural reduction in electrical resistance of hematite by three orders of magnitude at pressures 54-56 GPa strongly suggests the occurrence of a Mott transition. In MgGeO₃, special attention was paid to the dP/dT slope of the phase boundary between perovskite and post-perovskite phases. Spin transition of Fe²⁺ in (Mg_0.83Fe_0.17)O is also briefly reported.