High throughput thermal conductivity of high temperature solid phases: The case of oxide and fluoride perovskites

TL;DR

This study combines phonon calculations and machine learning to identify thermally stable cubic perovskites and analyze their thermal conductivities, revealing new stable compounds and insights into their temperature-dependent behavior.

Contribution

It introduces a high-throughput approach to assess stability and thermal properties of perovskites, discovering new stable compounds and structural factors influencing thermal conductivity.

Findings

92 mechanically stable compounds identified at high temperatures

Fluorides generally have lower thermal conductivity than oxides

Most cubic perovskites show slower than T^{-1} thermal conductivity decrease

Abstract

Using finite-temperature phonon calculations and machine-learning methods, we calculate the mechanical stability of about 400 semiconducting oxides and fluorides with cubic perovskite structures at 0 K, 300 K and 1000 K. We find 92 mechanically stable compounds at high temperatures -- including 36 not mentioned in the literature so far -- for which we calculate the thermal conductivity. We demonstrate that the thermal conductivity is generally smaller in fluorides than in oxides, largely due to a lower ionic charge, and describe simple structural descriptors that are correlated with its magnitude. Furthermore, we show that the thermal conductivities of most cubic perovskites decrease more slowly than the usual $T^{-1}$ behavior. Within this set, we also screen for materials exhibiting negative thermal expansion. Finally, we describe a strategy to accelerate the discovery of mechanically stable compounds at high temperatures.