  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.
