Characterization and analysis of thermoelectric transport in n-type Ba8Ga16xGe30+x

Andrew F. May, Eric S. Toberer, Ali Saramat, and G. Jeffrey Snyder
Phys. Rev. B 80, 125205 – Published 18 September 2009

Abstract

The thermoelectric transport properties of polycrystalline, n-type Ba8Ga16xGe30+x were characterized from 300 to 1000 K. The carrier density was found to vary precisely with the experimental x as expected from simple electron counting. The experimental data are analyzed within the framework of a single parabolic band model, which is found to accurately describe transport for the compositions of interest for thermoelectric application. The lattice thermal conductivity, calculated with a degeneracy adjusted Lorenz number, does not show a trend with composition and a value of 1Wm1K1 is observed at 300 K. A maximum figure of merit zT=0.86 is obtained at 950 K, and the optimal doping level for thermoelectric application is predicted to be 2×1020cm3, which corresponds to Ba8Ga15.75Ge30.25 by electron counting. An unexpected transition event is observed near 650 K, which results in a significant increase in the heat capacity.

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  • Received 27 May 2009

DOI:https://doi.org/10.1103/PhysRevB.80.125205

©2009 American Physical Society

Authors & Affiliations

Andrew F. May1,*, Eric S. Toberer2, Ali Saramat2, and G. Jeffrey Snyder2

  • 1Chemical Engineering, California Institute of Technology, 1200 E. California Boulevard, Pasadena, California 91125, USA
  • 2Materials Science, California Institute of Technology, 1200 E. California Boulevard, Pasadena, California 91125, USA

  • *may@caltech.edu

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Vol. 80, Iss. 12 — 15 September 2009

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