Anomalous thermal conductivity and suppression of negative thermal expansion in ScF3

TL;DR

This study uses ab-initio calculations to explain the thermal behavior of ScF3, revealing anomalous thermal conductivity and the suppression of negative thermal expansion at high temperatures, with implications for the perovskite class.

Contribution

It introduces a temperature-dependent phonon spectral approach to accurately describe thermal properties and the suppression of negative thermal expansion in ScF3.

Findings

Quantitative description of negative thermal expansion suppression

Prediction of anomalous thermal conductivity behavior

Discussion of mode Grüneisen parameters' role

Abstract

The empty perovskite ScF3 exhibits negative thermal expansion up to 1100 K. We demonstrate that ab-initio calculations of temperature-dependent effective phonon spectra allow to quantitatively describe the behavior of this compound and the suppression of negative thermal expansion. Based on this result, we predict an anomalous temperature dependence of the thermal conductivity and interpret it as a general feature of the perovskite class. Finally, we comment on the fact that the suppression of negative thermal expansion at such a high temperature is beyond the reach of the quasi-harmonic approximation and we discuss this suppression based on the temperature-dependence of the mode Gr\"uneisen parameters.