Tuning the charge carrier density in the thermoelectric colusite

Fiseong S. Kim, Koichiro Suekuni, Hirotaka Nishiate, Michihiro Ohta, Hiromi I. Tanaka, Toshiro Takabatake

Research output: Contribution to journalArticle

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Abstract

The colusite Cu 26 V 2 Sn 6 S 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 26- x Zn x V 2 Sn 6 S 32 (x = 1-3) and starting with Cu and Sn deficient compositions in Cu 26- y V 2 Sn 6 S 32 (y = 1, 2) and Cu 26 V 2 Sn 6- z S 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 26- y V 2 Sn 6 S 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 20 and 2.8 × 10 21 cm -3 . The relation between p and S led to the effective mass m∗ of 4-7m 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.

Original languageEnglish
Article number175105
JournalJournal of Applied Physics
Volume119
Issue number17
DOIs
Publication statusPublished - May 7 2016
Externally publishedYes

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charge carriers
tuning
thermoelectric materials
electron probes
Seebeck effect
microanalysis
figure of merit
x ray diffraction
valence
electrical resistivity

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

Kim, F. S., Suekuni, K., Nishiate, H., Ohta, M., Tanaka, H. I., & Takabatake, T. (2016). Tuning the charge carrier density in the thermoelectric colusite. Journal of Applied Physics, 119(17), [175105]. https://doi.org/10.1063/1.4948475

Tuning the charge carrier density in the thermoelectric colusite. / Kim, Fiseong S.; Suekuni, Koichiro; Nishiate, Hirotaka; Ohta, Michihiro; Tanaka, Hiromi I.; Takabatake, Toshiro.

In: Journal of Applied Physics, Vol. 119, No. 17, 175105, 07.05.2016.

Research output: Contribution to journalArticle

Kim, FS, Suekuni, K, Nishiate, H, Ohta, M, Tanaka, HI & Takabatake, T 2016, 'Tuning the charge carrier density in the thermoelectric colusite', Journal of Applied Physics, vol. 119, no. 17, 175105. https://doi.org/10.1063/1.4948475
Kim, Fiseong S. ; Suekuni, Koichiro ; Nishiate, Hirotaka ; Ohta, Michihiro ; Tanaka, Hiromi I. ; Takabatake, Toshiro. / Tuning the charge carrier density in the thermoelectric colusite. In: Journal of Applied Physics. 2016 ; Vol. 119, No. 17.
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