First-principles study of structural, electronic, ferroelectric, and vibrational properties of BiInO3 under high pressure

Abstract

We examine the structural, electronic, and vibrational properties of orthorhombic BiInO3 in the polar (Pna21 space group) and non-polar (Pnma space group) phases using density functional theory. We found that the Pna21 phase has a lower energy than the Pnma phase at 0 GPa. The spontaneous polarization of polar phase at 0 GPa is 67 μC/cm2. The phonon calculations confirm the dynamical stability of the Pna21 phase at 0 GPa. In contrast, the Pnma phase exhibits a distinct soft mode at the Γ point, which suggests a displacive character of the phase transition. The effect of hydrostatic pressure on the structural, ferroelectric, and vibrational properties of BiInO3 has been also investigated. We found the following sequence of phase transitions: Pna21 → Pna21/Pnma → Pnma, i.e. there is an intermediate region in which polar and non-polar phases can coexist. From the electronic structure calculations we found that the ferroelectric properties of BiInO3 in the Pna21 phase arise from the stereochemically active lone pairs on the Bi atoms. In the Pnma phase we observe an anti-polar arrangement of the lone pairs of Bi atoms. A comparison with the available experimental data was performed and the effect of different features (zero-point energy, exchange-correlation functional) on the obtained results was presented.