Phase stability and thermoelectric properties of TiCoSb-TiM2Sn (M = Ni, Fe) Heusler composites

Maryana Asaad, J. Buckman, R. I. Smith, Jan-Willem G. Bos

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Abstract

Heusler composites have attracted significant attention as a new route towards improving the thermoelectric figure of merit (ZT) through reduction of the lattice thermal conductivity and carrier filtering effects. This work extends this field by investigating TiCoSb-TiM2Sn (M = Ni, Fe) composites. All end-members are stable phases but no clean segregation into half- and full-Heusler phases was observed. Instead, for M = Ni, partial substitution on the Co sublattice and n-type doping occurs, combined with the formation of Ni3Sn2 and full-Heusler phases. For M = Fe, substitution on the Co site occurs, leading to p-type conduction. Rietveld analysis of neutron powder diffraction data reveals no evidence for the presence of metals on the vacant tetrahedral site, signalling the absence of embedded Heusler inclusions. The thermoelectric properties of both series vary systematically with composition. For both n-type (M = Ni) and p-type (M = Fe) series, the highest measured power factors S2/ρ ∼ 0.8 mW m−1 K−2 leading to ZT ∼ 0.12 at 713 K. This work extends knowledge regarding the phase stability and thermoelectric properties of TiCoSb-based Heusler composites.
Original languageEnglish
Pages (from-to)181-189
Number of pages9
JournalJournal of Solid State Chemistry
Volume276
Early online date4 May 2019
DOIs
Publication statusPublished - Aug 2019

Keywords

  • Half-Heusler alloys
  • Thermoelectric
  • TiCoSb

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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    Asaad, M. (Creator), Buckman, J. (Creator), Smith, R. I. (Creator) & Bos, J. G. (Creator), Heriot-Watt University, 7 May 2019

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