Uncompensated Polarization in Incommensurate Modulations of Perovskite Antiferroelectrics

TL;DR

This paper reveals complex incommensurate polar structures in PbZrO$_3$ antiferroelectrics, challenging previous assumptions of fully compensated antiparallel cation displacements and providing new atomic-level insights.

Contribution

It uncovers previously unknown arrangements of Pb-cation displacements in incommensurate modulations, supported by advanced microscopy and ab initio calculations.

Findings

Pb-cation displacements are antiparallel with different magnitudes

Displacements are nearly orthogonal in adjacent stripes

Ab initio calculations support low-energy configurations

Abstract

Complex polar structures of incommensurate modulations (ICMs) are revealed in chemically modified PbZrO$_3$ perovskite antiferroelectrics using advanced transmission electron microscopy techniques. The Pb-cation displacements, previously assumed to arrange in a fully-compensated antiparallel fashion, are found to be either antiparallel but with different magnitudes, or in a nearly orthogonal arrangement in adjacent stripes in the ICMs. Ab initio calculations corroborate the low-energy state of these arrangements. Our discovery corrects the atomic understanding of ICMs in PbZrO$_3$-based perovskite antiferroelectrics.