Origin of Low Thermal Conductivity in In4Se3
Journal
ACS Applied Energy Materials
Journal Volume
3
Journal Issue
12
Start Page
12549
End Page
12556
ISSN
25740962
Date Issued
2020
Author(s)
Luu, Son D.N.
Supka, Andrew R.
Nguyen, Van Huy
Vo, Dai Viet N.
Wojciechowski, Krzysztof Tomasz
Fornari, Marco
Vaqueiro, Paz
Abstract
In4Se3 is an attractive n-type thermoelectric material for midrange waste heat recovery, owing to its low thermal conductivity (?0.9 W·m- 1·K-1 at 300 K). Here, we explore the relationship between the elastic properties, thermal conductivity, and structure of In4Se3. The experimentally determined average sound velocity (2010 m·s-1), Young's modulus (47 GPa), and Debye temperature (198 K) of In4Se3 are rather low, indicating considerable lattice softening. This behavior, which is consistent with low thermal conductivity, can be related to the complex bonding found in this material, in which strong covalent In-In and In-Se bonds coexist with weaker electrostatic interactions. Phonon dispersion calculations show that Einstein-like modes occur at ?30 cm-1. These Einstein-like modes can be ascribed to weakly bonded In+ cations located between strongly bonded [(In3)5+(Se2-)3]- layers. The Gruneisen parameter for the soft-bonded In+ at the frequencies of the Einstein-like modes is large, indicating a high degree of bond anharmonicity and hence increased phonon scattering. The calculated thermal conductivity and elastic properties are in good agreement with experimental results.
Subjects
Gruneisen Parameter
Lattice Softening
Lone Pair
Thermal Conductivity
Thermoelectric Materials
Binary Alloys
Elastic Moduli
Elasticity
Phonons
Waste Heat
Waste Heat Utilization
Anharmonicities
Elastic Properties
Low Thermal Conductivity
Phonon Dispersions
Thermo-electric Materials
Thermal Conductivity
Publisher
American Chemical Society
Type
journal article