Synthesis, structure, and high temperature thermoelectric properties of Yb11Sb9.3Ge0.5

Japheth F. Rauscher, Susan M. Kauzlarich, Teruyuki Ikeda, G. Jeffrey Snyder

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Zintl phase compounds with large unit cells and complex anionic structures such as Yb11Sb10 hold potential for being good thermoelectric materials. Single crystals of Ge-doped Yb11Sb 10 were synthesized using a molten Sn-flux technique. Single crystal X-ray diffraction data were obtained and resulted in a composition of Yb 11Sb9.3Ge0.5 which was verified by microprobe. Yb11Sb9.3Ge0.5 is isostructural to Ho 11Ge10, crystallizing in a bodycentered, tetragonal unit cell, space group I4/mmm, with Z = 4. The unit cell parameters of Yb 11Sb9.3Ge0.5 are a = 11.8813(4), c = 17.1276(13) Å with a volume of 2417.8(2) Å3. These parameters correlate well with the structural refinement of previously published Yb11 Sb10- The structure consists of 16 isolated Sb 3- anions, 8 Sb2 4- dumbbells, 2 Sb 4 4- square planar rings and 44 Yb2+ cations. The Ge, doped in at 28 % occupancy, was found to be site specific, residing on the 2 Sb4 4- square planar rings. Single crystal X-ray diffraction is most consistent with the site that makes up the square ring being less than fully occupied. The doped compound is additionally characterized by X-ray powder diffraction, differential scanning calorimetry and thermogravimetry. High temperature (300-1200 K) thermoelectric properties show that the doped compound has extremely low thermal conductivity (10-30 mW/cmK), lower than that of Yb11Sb10. Temperature dependent resistivity is consistent with a heavily doped semiconductor. Yb 11Sb9.3Ge0.5 shows p-type behavior increasing from ∼22 μV/K at room temperature to ∼31 μV/K at 1140 K. The low value and the temperature dependence of the Seebeck coefficient suggest that bipolar conduction produces a compensated Seebeck coefficient and consequently a low zT.

Original languageEnglish (US)
Pages (from-to)1587-1594
Number of pages8
JournalZeitschrift fur Anorganische und Allgemeine Chemie
Volume633
Issue number10
DOIs
StatePublished - 2007

Keywords

  • Antimonides
  • Doping
  • Electrical resistivity
  • Figure of merit
  • High-temperature thermoelectric
  • Seebeck coefficient
  • Thermal conductivity
  • Zintl compounds

ASJC Scopus subject areas

  • Inorganic Chemistry

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