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Author Kim, Fiseong S. ♦ Suekuni, Koichiro ♦ Tanaka, Hiromi I. ♦ Nishiate, Hirotaka ♦ Ohta, Michihiro ♦ Takabatake, Toshiro
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY ♦ CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS ♦ CARRIER DENSITY ♦ CARRIERS ♦ CHARGE CARRIERS ♦ COPPER ♦ EFFECTIVE MASS ♦ ELECTRIC CONDUCTIVITY ♦ ELECTRON MICROPROBE ANALYSIS ♦ ELECTRON PROBES ♦ ELECTRONS ♦ HOLES ♦ PERFORMANCE ♦ POWDERS ♦ TEMPERATURE RANGE 0400-1000 K ♦ THERMOELECTRIC MATERIALS ♦ TIN ♦ TUNING ♦ VALENCE ♦ X-RAY DIFFRACTION ♦ ZINC
Abstract The colusite Cu{sub 26}V{sub 2}Sn{sub 6}S{sub 32} has high potential as a thermoelectric material at medium-high temperatures because of a large Seebeck coefficient (S ≃ 220 μV/K) and rather small electrical resistivity (ρ ≃ 100 μΩm) at 660 K. To improve the thermoelectric performance, we have tuned the hole carrier density p by substituting Zn for Cu in Cu{sub 26−x}Zn{sub x}V{sub 2}Sn{sub 6}S{sub 32} (x = 1–3) and starting with Cu and Sn deficient compositions in Cu{sub 26−y}V{sub 2}Sn{sub 6}S{sub 32} (y = 1, 2) and Cu{sub 26}V{sub 2}Sn{sub 6−z}S{sub 32} (z = 0.25–1), respectively. Powder x-ray diffraction and electron-probe microanalysis showed that the Zn-substituted samples and Sn-deficient (z ≥ 0.5) samples are formed in a single phase, whereas the Cu{sub 26−y}V{sub 2}Sn{sub 6}S{sub 32} samples are composed of two phases with slightly different compositions. Within these samples, the value of p at 300 K varies in the range between 3.6 × 10{sup 20} and 2.8 × 10{sup 21 }cm{sup −3}. The relation between p and S led to the effective mass m* of 4–7m{sub 0} for the hole carriers. The large S of the colusite is therefore ascribed to the heavy mass carriers of the valence band top. The decreases in p with x and y reduced the dimensionless thermoelectric figure of merit ZT, whereas the increase in p with z raised ZT from 0.56 (z = 0) to 0.62 (z = 0.5) at 660 K.
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-05-07
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 119
Issue Number 17


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