High-throughput study of the static dielectric constant at high temperatures in oxide and fluoride cubic perovskites

TL;DR

This study uses ab initio phonon calculations to efficiently predict the static dielectric constants of 78 cubic perovskite oxides and fluorides at high temperature, revealing significant dispersion differences and correlations with structural descriptors.

Contribution

It introduces a high-throughput computational approach for accurately estimating high-temperature dielectric constants in perovskites, validating against experiments and analyzing anharmonic effects.

Findings

Dielectric constant dispersion is much larger in oxides than fluorides at 1000 K.

The method accurately reproduces experimental temperature dependence of dielectric constants.

Dielectric constants are well correlated with infinite-frequency dielectric constants, even near phase transitions.

Abstract

Using finite-temperature phonon calculations and the Lyddane-Sachs-Teller relations, we calculate ab initio the static dielectric constants of 78 semiconducting oxides and fluorides with cubic perovskite structures at 1000 K. We first compare our method with experimental measurements, and we find that it succeeds in describing the temperature dependence and the relative ordering of the static dielectric constant $\epsilon_{DC}$ in the series of oxides BaTiO$_{3}$, SrTiO$_{3}$, KTaO$_{3}$. We show that the effects of anharmonicity on the ion-clamped dielectric constant, on Born charges, and on phonon lifetimes, can be neglected in the framework of our high-throughput study. Based on the high-temperature phonon spectra, we find that the dispersion of $\epsilon_{DC}$ is one order of magnitude larger amongst oxides than fluorides at 1000 K. We display the correlograms of the dielectric constants with simple structural descriptors, and we point out that $\epsilon_{DC}$ is actually well correlated with the infinite-frequency dielectric constant $\epsilon_{\infty}$, even in those materials with phase transitions in which $\epsilon_{DC}$ is strongly temperature-dependent.