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

Journal Article · Thu Jul 21 00:00:00 EDT 2016 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4959209· OSTI ID:22597767

Sun, Hui ^[1]; Lu, Xu ^[2]; Morelli, Donald T. ^[3]

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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)

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.

• OSTI ID: 22597767
• Journal Information: Journal of Applied Physics, Vol. 120, Issue 3; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

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