In Situ TEM Studies of Nanostructured Thermoelectric Materials: An Application to Mg-Doped Zn4 Sb3 Alloy

Duc-The Ngo; Le Thanh Hung; Ngo Van Nong

doi:10.1002/cphc.201700930

In Situ TEM Studies of Nanostructured Thermoelectric Materials: An Application to Mg-Doped Zn₄ Sb₃ Alloy

Chemphyschem. 2018 Jan 5;19(1):108-115. doi: 10.1002/cphc.201700930. Epub 2017 Nov 27.

Authors

Duc-The Ngo¹, Le Thanh Hung², Ngo Van Nong²

Affiliations

¹ Electron Microscopy Centre, School of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
² Department of Energy Conversion and Storage, Technical University of Denmark, DTU-Risø Campus, 4000, Roskilde, Denmark.

PMID: 28991398
DOI: 10.1002/cphc.201700930

Abstract

We demonstrate an advanced approach using state of the art in situ transmission electron microscopy (TEM) to understand the interplay between nanostructures and thermoelectric (TE) properties of high-performance Mg-doped Zn₄ Sb₃ TE systems. By using the technique, microstructure and crystal evolutions of TE material have been dynamically captured as a function of temperature from 300 K to 573 K. On heating, we have clearly observed precipitation and growth of a Zn-rich secondary phase as nanoinclusions in the matrix of primary Zn₄ Sb₃ phase. Elemental mapping by STEM-EDX spectroscopy reveals enrichment of Zn in the secondary Zn₆ Sb₅ nanoinclusions during the thermal processing without decomposition. Such nanostructures strongly enhances phonon scattering, resulting in a decrease in the thermal conductivity leading to a zT value of 1.4 at 718 K.

Keywords: Zn-Sb compounds; electron diffraction; energy transfer; materials science; solid-state structures.