Tunable electronic properties and low thermal conductivity in synthetic colusites Cu26-xZnxV2M6S 32 (x ≤ 4, M = Ge, Sn)

K. Suekuni, F. S. Kim, T. Takabatake

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Abstract

We have first synthesized Cu26-xZnxV 2M6S32 (x ≤ 4, M = Ge, Sn) with the cubic colusite structure and measured the thermoelectric properties. For both M = Ge and Sn, the samples with x = 0 show moderately large thermopower of +27 μV/K at 300 K. The metallic conduction of p-type carriers and Pauli-paramagnetic behavior are consistent with the electron-deficient character expected from the formal charge Cu 26 1 + V 2 5 + M 6 4 + S 32 2 -. The substitution of Zn for Cu results in significant increases in both the electrical resistivity and thermopower. The resistivity of the samples with x = 4 displays a three-dimensional variable-range hopping behavior at low temperatures. These facts indicate that the doped electrons fill the unoccupied states in the valence band and thereby the Fermi level moves to the localized electronic states at the top of the band. The lattice thermal conductivity is as low as ∼1 W/Km at 300 K for all samples. The structural and thermoelectric properties of the colusites are discussed in comparison with those of doped tetrahedrite Cu12-xZnxSb4S 13.

Original languageEnglish
Article number063706
JournalJournal of Applied Physics
Volume116
Issue number6
DOIs
Publication statusPublished - Aug 14 2014
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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