Pressure-induced phase transitions of multiferroic BiFeO3

TL;DR

This study investigates how pressure induces phase transitions in multiferroic BiFeO3, revealing a sequence of structural changes and phase coexistence using advanced X-ray diffraction techniques.

Contribution

It provides new experimental evidence of phase coexistence and identifies a previously unreported orthorhombic phase in BiFeO3 under pressure.

Findings

Rhombohedral to monoclinic transition at 7 GPa

Monoclinic to orthorhombic transition at 11 GPa

Coexistence of monoclinic and orthorhombic phases at 5-7 GPa

Abstract

Pressure-induced phase transitions of multiferroic BiFeO3 have been investigated using synchrotron radiation X-ray diffraction with diamond anvil cell technique at room temperature. Present experimental data clearly show that rhombohedral (R3c) phase of BiFeO3 first transforms to monoclinic (C2/m) phase at 7 GPa, then to orthorhombic (Pnma) phase at 11 GPa, which is consistent with recent theoretical ab initio calculation. However, we observe another peak at 2{\theta}=7{\deg} in the pressure range of 5-7 GPa that has not been reported previously. Further analysis reveals that this reflection peak is attributed to the orthorhombic (Pbam) phase, indicating the coexisting of monoclinic phase with orthorhombic phase in low pressure range.