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