Thermal conductivity of Magnesium Telluride (MgTe) -- A first principles study

TL;DR

This study uses first principles calculations to analyze the thermal conductivity of magnesium telluride (MgTe) across various phases, revealing ultra-low values at nanoscales suitable for thermoelectric applications.

Contribution

It provides a comprehensive first-principles analysis of MgTe's thermal conductivity in different phases and at nanoscales, highlighting its potential for thermoelectric use.

Findings

NiAs phase has the lowest thermal conductivity at 2.645 W/mK.

Nanometer-scale MgTe exhibits thermal conductivity below 1.4 W/mK.

Phonon scattering by low-frequency optical phonons dominates in the NiAs phase.

Abstract

In this work, we report thermal conductivity(k) of magnesium telluride (MgTe) with various crystallographic phases such as rocksalt, zincblende, wurtzite and nickel arsenic (NiAs) using density functional theory and Boltzmann transport equation. Our first principles calculations results show the low thermal conductivity of MgTe with kNiAs < krocksalt < kwurtzite < kzincblende. We systematically investigated the phonon group velocity, phonon scattering rate and mode contributed thermal conductivity of transverse acoustic (TA), longitudinal acoustic (LA) and optical phonons. Our first principles calculations shows that ultra-low thermal conductivity of 2.645 Wm-1K-1 for NiAs phase is due to the dominant scattering of TA and LA phonons by low frequency optical phonons. We also analyzed the length dependence thermal conductivity of MgTe at nanometer length-scales. At nanometer length scales such as 50 nm for NiAs phase, room temperature thermal conductivity of less than 1.4 Wm-1K-1 shows a promising nature of MgTe for thermoelectric applications.