Diffusive phase transitions in ferroelectrics and antiferroelectrics

TL;DR

This paper introduces a microscopic model and Landau theory to describe phase transitions in ferroelectrics and antiferroelectrics, focusing on relaxor behavior and coupling mechanisms affecting susceptibility.

Contribution

It presents a novel microscopic model and Landau theory for heterogeneous ferroelectrics and relaxors, with applications to specific materials and analysis of mode coupling effects.

Findings

Successful modeling of relaxor phase in ferroelectrics.

Insights into coupling between soft modes and domain walls.

Application to PbFe$_{1/2}$Ta$_{1/2}$O$_3$ and NaNbO$_3$:Gd.

Abstract

In this paper, we present a microscopic model for heterogeneous ferroelectric and an order parameter for relaxor phase. We write a Landau theory based on this model and its application to ferroelectric PbFe$_{1/2}$Ta$_{1/2}$O$_3$ (PFT) and antiferroelectric NaNbO$_3$:Gd. We later discuss the coupling between soft mode and domain walls, soft mode and quasi-local vibration and resulting susceptibility function.