Thermoelectric properties and electronic structure of the zintl-phase Sr3AlSb3

Alex Zevalkink, Gregory Pomrehn, Yoshiki Takagiwa, Jessica Swallow, G. Jeffrey Snyder*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

The Zintl-phase Sr3AlSb3, which contains relatively earth-abundant and nontoxic elements, has many of the features that are necessary for good thermoelectric performance. The structure of Sr 3AlSb3 is characterized by isolated anionic units formed from pairs of edge-sharing tetrahedra. Its structure is distinct from previously studied chain-forming structures, Ca3AlSb3 and Sr 3GaSb3, both of which are known to be good thermoelectric materials. DFT predicts a relatively large band gap in Sr3AlSb 3 (Eg≈1eV) and a heavier band mass than that found in other chain-forming A3MSb3 phases (A=Sr, Ca; M=Al, Ga). High-temperature transport measurements reveal both high resistivity and high Seebeck coefficients in Sr3AlSb3, which is consistent with the large calculated band gap. The thermal conductivity of Sr 3AlSb3 is found to be extremely low (≈ 0.55W mK -1 at 1000K) due to the large, complex unit cell (56 atoms per primitive cell). Although the figure of merit (zT) has not been optimized in the current study, a single parabolic band model suggests that, when successfully doped, zT≈ 0.3 may be obtained at 600K; this makes Sr3AlSb 3 promising for waste-heat recovery applications. Doping with Zn 2+ on the Al3+ site has been attempted, but does not lead to the expected increase in carrier concentration. Zintlating chemistry! The Zintl compound Sr3AlSb3 exhibits a band gap of about 0.6eV, intrinsic electronic properties, and extremely low lattice thermal conductivity; this makes it a promising material for high-temperature thermoelectric applications (see picture).

Original languageEnglish (US)
Pages (from-to)2316-2321
Number of pages6
JournalChemSusChem
Volume6
Issue number12
DOIs
StatePublished - Dec 2013

Keywords

  • density functional calculations
  • electronic transport
  • thermal transport
  • zintl phases

ASJC Scopus subject areas

  • Environmental Chemistry
  • Chemical Engineering(all)
  • Materials Science(all)
  • Energy(all)

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