Formation and switching of defect dipoles in acceptor doped lead titanate: A kinetic model based on first-principles calculations

TL;DR

This paper develops a kinetic model, based on first-principles calculations, to describe the formation, alignment, and switching of defect dipoles in acceptor doped lead titanate, explaining aging and deaging phenomena in piezoelectric ceramics.

Contribution

It introduces a kinetic model extending the Arlt-Neumann model, incorporating first-principles energy barriers for defect dynamics in lead titanate.

Findings

Predicts the time scale for defect dipole alignment with spontaneous polarization.

Describes the dynamic equilibrium of defect dipoles under cycling conditions.

Links defect dipole behavior to aging and deaging in piezoelectric ceramics.

Abstract

The formation and field-induced switching of defect dipoles in acceptor doped lead titanate is described by a kinetic model representing an extension of the well established Arlt-Neumann model [Ferroelectrics {\bf 76}, 303 (1987)]. Energy barriers for defect association and reorientation of oxygen vacancy-dopant (Cu and Fe) complexes are obtained from first-principles calculations and serve as input data for the kinetic coefficients in the rate equation model. The numerical solution of the model describes the time evolution of the oxygen vacancy distribution at different temperatures and dopant concentrations in the presence or absence of an alternating external field. We predict the characteristic time scale for the alignment of all defect dipoles with the spontanenous polarization of the surrounding matrix. In this state the defect dipoles act as obstacles for domain wall motion and contribute to the experimentally observed aging. Under cycling conditions the fully aligned configuration is perturbed and a dynamic equilibrium is established with defect dipoles in parallel and anti-parallel orientation relative to the spontaneous polarization. This process can be related to the deaging behavior of piezoelectric ceramics.