Effects of Vacancies on Properties of Relaxor Ferroelectrics: a First-Principles Study

TL;DR

This study uses first-principles modeling to explore how lead vacancies affect the dielectric and ferroelectric properties of relaxor ferroelectric PSN, revealing that vacancies create inhomogeneous fields that influence phase transition behaviors.

Contribution

It introduces a first-principles-based model to analyze the impact of lead vacancies on relaxor ferroelectrics, providing new insights into their dielectric behavior and transition characteristics.

Findings

Lead vacancies generate inhomogeneous electric fields.

Vacancies broaden dielectric peaks at lower temperatures.

Lead vacancies smear properties near the ferroelectric transition.

Abstract

A first-principles-based model is developed to investigate the influence of lead vacancies on the properties of relaxor ferroelectric Pb(Sc1/2Nb1/2)O3 (PSN). Lead vacancies generate large, inhomogeneous, electric fields that reduce barriers between energy minima for different polarization directions. This naturally explains why relaxors with significant lead vacancy concentrations have broadened dielectric peaks at lower temperatures, and why lead vacancies smear properties in the neighborhood of the ferroelectric transition in PSN. We also reconsider the conventional wisdom that lead vacancies reduce the magnitude of dielectric response.