Tuning the charge carrier density in the thermoelectric colusite

Journal Article · Sat May 07 00:00:00 EDT 2016 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4948475· OSTI ID:22596944

Kim, Fiseong S.; Suekuni, Koichiro; Tanaka, Hiromi I. ^[1]; Nishiate, Hirotaka; Ohta, Michihiro ^[2]; Takabatake, Toshiro ^[1]

---

1. Department of Quantum Matter, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8530 (Japan)
2. Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan)

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.

• OSTI ID: 22596944
• Journal Information: Journal of Applied Physics, Vol. 119, Issue 17; 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

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
71 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