High-pressure phase transitions inBiMO3(M=Al, Ga, and In):In situx-ray diffraction and Raman scattering experiments

Abstract

In situ x-ray diffraction and Raman scattering experiments using a diamond anvil cell revealed high-pressure forms of BiMO 3 ͑M = Al, Ga, and In͒ under hydrostatic conditions at room temperature. Various perovskitetype 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 BiAlO 3 , BiGaO 3 , and BiInO 3 perovskite, respectively. Structure systematics of the BiMO 3 perovskites is given on the basis of the cationic size of M 3+ .

Electronic structure, ferroelectric properties, and phase stability of BiGaO3 under high pressure from first principles

“…The theoretical prediction of the first phase transition from pyroxene Pcca to perovskite monoclinic Cm phase agrees well with the experimental findings reported in Ref. [10]. The calculated transition pressure of 3.5 GPa is in good agreement with the experimental result of 3.2 GPa from Ref.…”

“…The calculated transition pressure of 3.5 GPa is in good agreement with the experimental result of 3.2 GPa from Ref. [10]. For higher values of pressure there is no such agreement.…”

“…The first disagreement is that the theoretical values of transition pressure are lower than the experimental ones. The second disagreement is that R3c and Pnma phases were not observed in the experiment [10].…”

“…Experimentally established structural data from Refs. [7,10] were used as input for the calculations. The Brillouin zone integrations were performed using 12 9 12 9 12, 8 9 8 9 8, 8 9 8 9 8, and 6 9 6 9 6 Gamma-centered k-point grids for cell with 5-(Pm3m, P4mm, R3m), 10-(C2/m, Cm, R3c, R-3c), 20-(C2/c, Cmcm, Imma, Pcca, Pnma), and 40-atoms (Pbam), respectively.…”

“…The nonpolar orthorhombic (space groups Imma and Pnma) and monoclinic (space group C2/c) phases were observed in bulk BiCr 1-x Ga x O 3 [7,9] and BiMn 1-x Ga x O 3 [7]. In the first report on structural behavior of BiGaO 3 as a function of pressure, Yusa et al [10] showed that it undergoes three pressure-induced phase transitions in the 0-11 GPa range, from pyroxene structure (Pcca space group) to the perovskite-like monoclinic Cm phase, and then to the orthorhombic Cmcm, and finally from Cmcm to Pbam structure at 3.2, 6.3, and 9.8 GPa, respectively.…”