Low thermal conductivity and triaxial phononic anisotropy of SnSe

TL;DR

This theoretical study reveals that SnSe exhibits extremely low thermal conductivity with significant anisotropy across its crystallographic axes, aligning well with experimental data and highlighting its potential for thermoelectric applications.

Contribution

The paper provides a detailed ab-initio analysis explaining the origins of low thermal conductivity and anisotropic heat conduction in SnSe, contrasting previous experimental and theoretical findings.

Findings

SnSe has very low lattice thermal conductivity similar to amorphous materials.

There is a strong anisotropy in thermal conductivity between crystallographic axes.

Results align with most experimental data, differing from recent isotropic reports.

Abstract

In this theoretical study, we investigate the origins of the very low thermal conductivity of tin selenide (SnSe) using ab-initio calculations. We obtained high-temperature lattice thermal conductivity values that are close to those of amorphous compounds. We also found a strong anisotropy between the three crystallographic axes: one of the in-plane directions conducts heat much more easily than the other. Our results are compatible with most of the experimental literature on SnSe, and differ markedly from the more isotropic values reported by a recent study.