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Title: Isovalent substitutes play in different ways: Effects of isovalent substitution on the thermoelectric properties of CoSi{sub 0.98}B{sub 0.02}

Abstract

Boron-added CoSi, CoSi{sub 0.98}B{sub 0.02}, possesses a very high thermoelectric power factor of 60 μW cm{sup −1} K{sup −2} at room temperature, which is among the highest power factors that have ever been reported for near-room-temperature thermoelectric applications. Since the electrical properties of this material have been tuned properly, isovalent substitution for its host atoms is intentionally employed to reduce the lattice thermal conductivity while maintaining the electronic properties unchanged. In our previous work, the effect of Rh substitution for Co atoms on the thermoelectric properties of CoSi{sub 0.98}B{sub 0.02} has been studied. Here, we present a study of the substitution of Ge for Si atoms in this compound. Even though Ge and Rh are isovalent with their corresponding host atoms, they play different roles in determining the electrical and thermal transport properties. Through the evaluation of the lattice thermal conductivity by the Debye approximation and the comparison between the high-temperature Seebeck coefficients, we propose that Rh substitution leads to a further overlapping of the conduction and the valence bands, while Ge substitution only shifts the Fermi level upward into the conduction band. Our results show that the influence of isovalent substitution on the electronic structure cannot be ignored when themore » alloying method is used to improve thermoelectric properties.« less

Authors:
 [1];  [2];  [3]
  1. Department of Basic Teaching, Anhui Institute of Information Technology, Wuhu, Anhui 241000 (China)
  2. College of Physics, Chongqing University, Chongqing 401331 (China)
  3. Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824 (United States)
Publication Date:
OSTI Identifier:
22597767
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 120; Journal Issue: 3; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-8979
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; APPROXIMATIONS; ATOMS; BORON ADDITIONS; COBALT BORIDES; COMPARATIVE EVALUATIONS; DEBYE TEMPERATURE; ELECTRONIC STRUCTURE; FERMI LEVEL; POWER FACTOR; SILICON BORIDES; TEMPERATURE RANGE 0273-0400 K; TEMPERATURE RANGE 0400-1000 K; THERMAL CONDUCTIVITY; THERMOELECTRIC PROPERTIES

Citation Formats

Sun, Hui, Lu, Xu, and Morelli, Donald T. Isovalent substitutes play in different ways: Effects of isovalent substitution on the thermoelectric properties of CoSi{sub 0.98}B{sub 0.02}. United States: N. p., 2016. Web. doi:10.1063/1.4959209.
Sun, Hui, Lu, Xu, & Morelli, Donald T. Isovalent substitutes play in different ways: Effects of isovalent substitution on the thermoelectric properties of CoSi{sub 0.98}B{sub 0.02}. United States. doi:10.1063/1.4959209.
Sun, Hui, Lu, Xu, and Morelli, Donald T. Thu . "Isovalent substitutes play in different ways: Effects of isovalent substitution on the thermoelectric properties of CoSi{sub 0.98}B{sub 0.02}". United States. doi:10.1063/1.4959209.
@article{osti_22597767,
title = {Isovalent substitutes play in different ways: Effects of isovalent substitution on the thermoelectric properties of CoSi{sub 0.98}B{sub 0.02}},
author = {Sun, Hui and Lu, Xu and Morelli, Donald T.},
abstractNote = {Boron-added CoSi, CoSi{sub 0.98}B{sub 0.02}, possesses a very high thermoelectric power factor of 60 μW cm{sup −1} K{sup −2} at room temperature, which is among the highest power factors that have ever been reported for near-room-temperature thermoelectric applications. Since the electrical properties of this material have been tuned properly, isovalent substitution for its host atoms is intentionally employed to reduce the lattice thermal conductivity while maintaining the electronic properties unchanged. In our previous work, the effect of Rh substitution for Co atoms on the thermoelectric properties of CoSi{sub 0.98}B{sub 0.02} has been studied. Here, we present a study of the substitution of Ge for Si atoms in this compound. Even though Ge and Rh are isovalent with their corresponding host atoms, they play different roles in determining the electrical and thermal transport properties. Through the evaluation of the lattice thermal conductivity by the Debye approximation and the comparison between the high-temperature Seebeck coefficients, we propose that Rh substitution leads to a further overlapping of the conduction and the valence bands, while Ge substitution only shifts the Fermi level upward into the conduction band. Our results show that the influence of isovalent substitution on the electronic structure cannot be ignored when the alloying method is used to improve thermoelectric properties.},
doi = {10.1063/1.4959209},
journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 3,
volume = 120,
place = {United States},
year = {2016},
month = {7}
}