Phys. Rev. Lett. 101, 155704 (2008) [4 pages]First-Principles Theory of Competing Order Types, Phase Separation, and Phonon Spectra in Thermoelectric AgPbmSbTem+2 AlloysReceived 27 February 2008; revised 30 July 2008; published 10 October 2008 Using a first-principles cluster expansion, we shed light on the solid-state phase diagram and structure of the recently discovered high-performance Pb-Ag-Sb-Te thermoelectrics. The calculated bulk thermodynamics favors the formation of coherent precipitates of ordered AgmSbnTem+n phases immiscible with rocksalt PbTe, such as AgSbTe2. The solubility is high for Pb in AgSbTe2 and low for (Ag,Sb) in PbTe (8% vs 0.6% at 850 K). The differences in the phonon spectra of PbTe and AgSbTe2 suggest that these precipitates enhance the thermoelectric performance by lowering thermal conductivity. © 2008 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.101.155704
DOI:
10.1103/PhysRevLett.101.155704
PACS:
64.75.Qr, 61.66.Fn, 63.20.dk, 64.70.kg
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