An In Situ SEM Experimental Study of the Thermal Stability of a LAST Thermoelectric Material

Ren, F., J.Y. Howe, L.R. Walker, E.D. Case and E. Lara-Curzio, 2012
Fusion TEM holder tip
Image courtesy of Philos. Mag. Lett.

Abstract

Thermal stability is a requirement for the deployment of thermoelectric (TE) materials in the application of power generation. Lead–antimony–silver–tellurium (LAST) is an emerging material with promising TE properties. This study focuses on the thermal stability of a LAST sample with composition Ag0.86Pb19SbTe20 fabricated from a cast ingot. Using a customized heating stage, the morphology of the LAST particles was studied via scanning electron microscopy (SEM) in situ, between room temperature and 848 K. The material was found to be stable below 823 K. The inclusion phase, which was antimony-rich, had a lower thermal stability than the PbTe-rich matrix. SEM findings were consistent with the results of a thermogravimetric analysis. The results from an in situ heating study suggest that protective environments should be used during the processing and application of LAST materials.

Impact Statement

Observed the thermal stability of LAST (lead antimony silver telluride, used in thermoelectrics) materials using Fusion in an S-3400 Hitachi SEM. The material was stable up to 823K. Above this temperature volatile components of the material because to vaporize, shrinking the overall particle sizes and leaving less volatile materials behind. They found that heating in vacuum in the SEM showed different results than heating in inert (argon) atmospheres. LAST should also not be operated above 773K due to the volatility of those components.