Tuning the charge carrier density in the thermoelectric colusite

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

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25 Citations (Scopus)

Abstract

The colusite Cu26V2Sn6S32 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 Cu26- xZnxV2Sn6S32 (x = 1-3) and starting with Cu and Sn deficient compositions in Cu26- yV2Sn6S32 (y = 1, 2) and Cu26V2Sn6- zS32 (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 Cu26- yV2Sn6S32 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 × 1020 and 2.8 × 1021cm-3. The relation between p and S led to the effective mass m∗ of 4-7m0 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

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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