Stability and low-energy orientations of interphase boundaries in multiaxial ferroelectrics: Phase-field simulations

TL;DR

This paper develops a thermodynamic model and phase-field simulations to predict and analyze the stability and orientations of interphase boundaries in multiaxial ferroelectrics, aiding in material design.

Contribution

It introduces a comprehensive thermodynamic framework combined with phase-field simulations to understand interphase boundary stability in ferroelectrics.

Findings

Low-energy boundary orientations are mainly determined by electrostatic and elastic energy minimization.

Electrical and mechanical incompatibilities can cause symmetry lowering near phase boundaries.

The model explains experimentally observed low-symmetry phases at morphotropic boundaries.

Abstract

The coexistence of different ferroelectric phases enables the tunability of the macroscopic properties and extensive applications from piezoelectric transducers to nonvolatile memories. Here we develop a thermodynamic model to predict the stability and low-energy orientations of boundaries between different phases in ferroelectrics. Taking lead zirconate titanate and bismuth ferrite as two examples, we demonstrate that the low-energy orientations of interphase boundaries are largely determined by minimizing the electrostatic and elastic energies. Phase-field simulations are employed to analyze the competition between the interfacial energy and the electrostatic and elastic energies. Our simulation results demonstrate that the lowering of crystal symmetry could occur due to the electrical and mechanical incompatibilities between the two phases, which can be used to explain the experimentally observed low-symmetry phases near morphotropic phase boundaries. Our work provides theoretical foundations for understanding and controlling the interphase boundaries in ferroelectric materials for multifunctional applications.