Temperature Driven Structural Phase Transition in Tetragonal-Like BiFeO3

TL;DR

This study reveals a temperature-induced structural phase transition in highly-strained BiFeO3, shifting from a monoclinic to a tetragonal-like phase around 100°C, impacting its ferroelectric properties.

Contribution

It provides detailed temperature-dependent x-ray diffraction data showing a phase transition in BiFeO3, clarifying its structural behavior at different temperatures.

Findings

Structural phase transition at ~100°C from M_C to M_A phase.

High-temperature phase retains tetragonal-like characteristics.

Ferroelectric properties are strongly temperature dependent.

Abstract

Highly-strained BiFeO3 exhibits a "tetragonal-like, monoclinic" crystal structure found only in epitaxial films (with an out-of-plane lattice parameter exceeding the in-plane value by >20%). Previous work has shown that this phase is properly described as a M$_{C}$ monoclinic structure at room temperature [with a (010)$_{pc}$ symmetry plane, which contains the ferroelectric polarization]. Here we show detailed temperature-dependent x-ray diffraction data that evidence a structural phase transition at ~100C to a high-temperature M$_{A}$ phase ["tetragonal-like" but with a (1-10)$_{pc}$ symmetry plane]. These results indicate that the ferroelectric properties and domain structures of strained BiFeO$_3$ will be strongly temperature dependent.