| About this Abstract |
| Meeting |
2020 TMS Annual Meeting & Exhibition
|
| Symposium
|
Alloys and Compounds for Thermoelectric and Solar Cell Applications VIII
|
| Presentation Title |
Lattice Hardening Due to Vacancy Diffusion in (GeTe)<sub>m</sub>Sb<sub>2</sub>Te<sub>3</sub> Alloys |
| Author(s) |
Alexandra Zevalkink, Wanyue Peng, David Smiadak, Michael Boehlert, Spencer Mathers, Jared Williams, Donald Morelli |
| On-Site Speaker (Planned) |
Alexandra Zevalkink |
| Abstract Scope |
GeTe-Sb2Te3 alloys in recent years have emerged as excellent thermoelectric materials, with reports of zT > 2 for Ge-rich compositions. These alloys exhibit a solid-state phase transition from a layered rhombohedral structure to a cubic rocksalt structure at intermediate temperatures. It is typical for materials to soften with increasing temperature due to thermal expansion, which impacts the speed of sound and thermal conductivity. While we observe softening in GeTe, Sb2Te3, and Bi2Te3 with increasing temperature, our study reveals anomalous hardening of the elastic moduli in the alloy (GeTe)<sub>17</sub>Sb2Te3 leading up to the phase transition. We attribute this to the gradual diffusion of the vacancies preceding the phase transition from a layered compound to a cubic structure and we expect such stiffening is a general feature of all (GeTe)mSb2Te3 and (GeTe)mBi2Te3 alloys, playing a fundamental role in the thermal conductivity in this important class of thermoelectric materials. |
| Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |