Lanthanum telluride (La3-xTe4) is a high-performance, next-generation thermoelectric material with a thermoelectric dimensionless figure of merit (zT) of 1.1 at 1273 K (x= 0.23) and has potential applications in radioisotope thermoelectric generators (RTGs) to power the space missions conducted by National Aeronautics and Space Administration (NASA). It has been shown that thezTcan be increased by 30% when nickel (Ni) nanoparticle inclusions are introduced to the La3-xTe4matrix. The coherent interfaces between La3-xTe4and Ni are likely a key factor determining the stability and performance of the La3-xTe4-Ni composites, but their role and nature are not well understood. It is important to determine the stability of the La3-xTe4/Ni interface in deep-space conditions, in addition to the effect of heat and oxygen on the mechanisms and kinetics of interface degradation. Here, we show the high-resolution structural characterization and the epitaxial crystallographic relationship of La3-xTe4-Ni thermoelectric composites and their interfaces at high-vacuum and ambient-temperature conditions using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). We further demonstrate the La3-xTe4/Ni interface degradation and Ni diffusion over its operating temperature range (25-1000 °C), in the presence and absence of oxygen, in real time, usingin situTEM.
|Number of pages
|Journal of Physical Chemistry C
|Published - Sep 30 2021
Bibliographical noteFunding Information:
This work was supported by the National Science Foundation under DMR 1455154 (M.P.T. and B.S.G.) and OIA 1355438 (partial salary support for M.P.T.). Partial salary support was provided by NASA Kentucky under NASA Award NN15AK28A (M.P.T.) and by the Research Corporation for Science Advancement via Scialog Award 26329 (A.U.). In situ TEM and a part of the EDS characterizations were conducted at the electron microscopy center (EMC), which belongs to the National Science Foundation NNCI Kentucky Multiscale Manufacturing and Nano Integration Node, supported by ECCS-1542174. High-resolution TEM characterizations involving the AP holder were conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science user facility.
© 2021 American Chemical Society
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Energy (all)
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films