Atomistic mechanisms governing structural stability change of zinc antimony thermoelectrics

TL;DR

This study investigates the microscopic atomistic mechanisms behind the structural stability change of zinc antimony thermoelectrics at high temperatures, revealing a migration-induced transition to a more stable crystal phase.

Contribution

It combines molecular dynamics simulations with experimental data to elucidate the atom migration process responsible for structural stability in zinc antimony thermoelectrics.

Findings

Temperature-dependent transport coefficients are correlated with structural transition.

Zn atoms migrate between interstitial sites during the transition.

The transition results in a more stable β-Zn4Sb3 crystal structure.

Abstract

The structural stability of thermoelectric materials is a subject of growing importance for their energy harvesting applications. Here, we study the microscopic mechanisms governing the structural stability change of zinc antimony at its working temperature, using molecular dynamics combined with experimental measurements of the electrical and thermal conductivity. Our results show that the temperature-dependence of the thermal and electrical transport coefficients is strongly correlated with a structural transition. This is found to be associated with a relaxation process, in which a group of Zn atoms migrates between interstitial sites. This atom migration gradually leads to a stabilizing structural transition of the entire crystal framework, and then results in a more stable crystal structure of $\beta-$ Zn4Sb3 at high temperature.