A new look at the temperature-dependent properties of the antiferroelectric model PbZrO3: an effective Hamiltonian study

TL;DR

This study introduces a new effective Hamiltonian approach to model the temperature-dependent properties of PbZrO3, successfully reproducing known phases and predicting a novel intermediate state with significant dielectric and thermal properties.

Contribution

A novel atomistic effective Hamiltonian scheme with bilinear coupling is developed to accurately model PbZrO3's phase transitions and predict a new intermediate phase.

Findings

Reproduces experimental phases of PbZrO3 at low and high temperatures.

Predicts a new intermediate Pbam phase with unique properties.

Supports findings with first-principles calculations.

Abstract

A novel atomistic effective Hamiltonian scheme, incorporating an original and simple bilinear energetic coupling, is developed and used to investigate the temperature dependent physical properties of the prototype antiferroelectric PbZrO3 (PZO) system. This scheme reproduces very well the known experimental hallmarks of the complex Pbam orthorhombic phase at low temperatures and the cubic paraelectric state of Pm 3m symmetry at high temperatures. Unexpectedly, it further predicts a novel intermediate state also of Pbam symmetry, but in which anti-phase oxygen octahedral tiltings have vanished with respect to the Pbam ground state. Interestingly, such new state exhibits a large dielectric response and thermal expansion that remarkably agree with previous experimental observations and the x-ray experiments we performed. We also conducted direct first-principles calculations at 0K which further support such low energy phase. Within this fresh framework, a re-examination of the properties of PZO is thus called for.