High-pressure phase transitions in BiMO3 (M=Al, Ga, and In): In situ x-ray diffraction and Raman scattering experiments

In situ x-ray diffraction and Raman scattering experiments using a diamond anvil cell revealed high-pressure forms of BiMO3 (M=Al, Ga, and In) under hydrostatic conditions at room temperature. Various perovskite-type structures are found in each compound under pressure up to 11 GPa. However, none of the high-pressure forms was quenched at atmospheric pressure. All of the phase transitions are confirmed to be reversible. During decompression, symmetry changes, R3m to R3c, Cmcm to Cm, and Pnma to Pna2(1) are observed in BiAlO3, BiGaO3, and BiInO3 perovskite, respectively. Structure systematics of the BiMO3 perovskites is given on the basis of the cationic size of M3+.