A Theory for Diffusionless Structural Phase Transitions in BaTiO3 and PZT Single Crystals

TL;DR

This paper develops a phenomenological theory to predict diffusionless phase transitions and crystal structures in BaTiO3 and PZT single crystals, emphasizing the role of anisotropy constants and strain in phase boundary formation.

Contribution

It introduces a new theoretical framework linking anisotropy and strain to phase transitions and morphotropic boundaries in ferroelectric crystals.

Findings

Phase transitions in BaTiO3 can be predicted using anisotropy and strain constants.

Morphotropic phase boundaries in PZT are explained by crystalline anisotropy.

The theory aligns with observed crystal structures and phase behaviors.

Abstract

A phenomenological theory has been proposed for the diffusionless structural phase transitions in crystalline solids here. It has been found that for BaTiO3 single crystal, both the phase transitions and the crystal structures can be predicted with the crystalline anisotropy constants and order parameter dependent strain constants that depend on the temperature. The results have also shown that the morphotropic phase boundaries in PZT crystals arise from the crystalline anisotropy.