Enhancement of the thermoelectric power factor by tuning the carrier concentration in Cu-rich and Ge-poor colusites Cu26+: XNb2Ge6- xS32

Yohan Bouyrie, Raju Chetty, Koichiro Suekuni, Noriyuki Saitou, Priyanka Jood, Noriko Yoshizawa, Toshiro Takabatake, Michihiro Ohta

Research output: Contribution to journalArticle

Abstract

Non-stoichiometric colusites Cu26+xNb2Ge6-xS32 (0 ≤ x ≤ 0.7) were prepared by mixing elemental constituents in evacuated quartz tubes at 1323 K followed by hot-pressing at 973 K. Their thermoelectric properties were investigated over the temperature range of 300 K-670 K. X-ray diffractometry and transmission electron microscopy analyses revealed that all the samples have a well crystallized structure and consist of the ordered colusite phase in which Cu, Nb, and Ge cations occupy their respective atomic positions in the structure. Energy dispersive spectroscopy analysis showed the presence of sulfur-poor and cation-rich chemical compositions in all the samples. We demonstrate that the increase of x (Cu-rich and Ge-poor) leads to an increase of the carrier concentration, resulting in a high power factor of ∼830 μW m-1 K-2 at 670 K for the sample with x = 0.5. High-temperature sintering led to significant defects of sulfur and interstitial cations, which resulted in a low lattice thermal conductivity (∼0.4 W m-1 K-1 at 670 K). A ZT of 0.7-0.8 was achieved at 670 K irrespective of the value of x.

Original languageEnglish
Pages (from-to)6442-6449
Number of pages8
JournalJournal of Materials Chemistry C
Volume8
Issue number19
DOIs
Publication statusPublished - May 21 2020

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Chemistry

Fingerprint Dive into the research topics of 'Enhancement of the thermoelectric power factor by tuning the carrier concentration in Cu-rich and Ge-poor colusites Cu<sub>26+: X</sub>Nb<sub>2</sub>Ge<sub>6- x</sub>S<sub>32</sub>'. Together they form a unique fingerprint.

  • Cite this