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Issue 4, 2010
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Electronic structure and transport in thermoelectric compounds AZn2Sb2 (A = Sr, Ca, Yb, Eu)

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Abstract

The AZn2Sb2 (P[3 with combining macron]m1, A = Ca, Sr, Eu, Yb) class of Zintl compounds has shown high thermoelectric efficiency (zT∼ 1) and is an appealing system for the development of Zintl structure–property relationships. High temperature transport measurements have previously been conducted for all known compositions except for SrZn2Sb2; here we characterize polycrystalline SrZn2Sb2 to 723 K and review the transport behavior of the other compounds in this class. Consistent with the known AZn2Sb2 compounds, SrZn2Sb2 is found to be a hole-doped semiconductor with a thermal band gap ∼ 0.27 eV. The Seebeck coefficients of the AZn2Sb2 compounds are found to be described by similar effective mass (m* ∼ 0.6 me). Electronic structure calculations reveal similar m* is due to antimony p states at the valence band edge which are largely unaffected by the choice of A-site species. However, the choice of A-site element has a dramatic effect on the hole mobility, with the room temperature mobility of the rare earth-based compositions approximately double that found for Ca and Sr on the A site. This difference in mobility is examined in the context of electronic structure calculations.

Graphical abstract: Electronic structure and transport in thermoelectric compounds AZn2Sb2 (A = Sr, Ca, Yb, Eu)

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Publication details

The article was received on 15 Jul 2009, accepted on 16 Sep 2009 and first published on 23 Oct 2009


Article type: Paper
DOI: 10.1039/B914172C
Citation: Dalton Trans., 2010,39, 1046-1054
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    Electronic structure and transport in thermoelectric compounds AZn2Sb2 (A = Sr, Ca, Yb, Eu)

    E. S. Toberer, A. F. May, B. C. Melot, E. Flage-Larsen and G. J. Snyder, Dalton Trans., 2010, 39, 1046
    DOI: 10.1039/B914172C

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