Effects of aging and annealing on the polar and antiferrodistortive components of the antiferroelectric transition in PZT

TL;DR

This study investigates how aging and annealing affect the separate polar and antiferrodistortive components of the antiferroelectric transition in PZT, revealing their distinct kinetics, elastic anomalies, and the role of defect structures.

Contribution

It introduces a phenomenological model that explains elastic compliance anomalies based on the separate transitions and their progression, incorporating effects of aging and annealing.

Findings

Separate polar and AFD transitions occur with different kinetics.

Elastic compliance anomalies can be modeled by steps in elastic modulus.

Aging induces defect formation that softens the lattice, reversible by annealing.

Abstract

The antipolar and antiferrodistortive (AFD) components of the antiferroelectric (AFE) transition in PbZr1-xTixO3 (x=0.054) can occur separately and with different kinetics, depending on the sample history, and are accompanied by elastic softening and stiffening, respectively. Together with the softening that accompanies octahedral tilting in the fraction of phase that is not yet transformed into AFE, they give rise to a variety of shapes of the curves of the elastic compliance versus temperature. All such anomalies found in samples with x=0.046 and 0.054, in addition to those already studied at x=0.050, can be fitted consistently with a phenomenological model based on the simple hypothesis that each of the polar and AFD transitions produces a step in the elastic modulus, whose position in temperature and width reflect the progress of each transition. The slowing of the kinetics of the transformations is correlated with the formation of defect structures during aging in the ferroelectric or AFE state, which are also responsible for a progressive softening of the lattice with time and thermal cycling, until annealing at high temperature recovers the initial conditions.