Abstract
The thermoelectric transport properties of polycrystalline, -type were characterized from 300 to 1000 K. The carrier density was found to vary precisely with the experimental 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 is observed at 300 K. A maximum figure of merit is obtained at 950 K, and the optimal doping level for thermoelectric application is predicted to be , which corresponds to by electron counting. An unexpected transition event is observed near 650 K, which results in a significant increase in the heat capacity.
7 More- Received 27 May 2009
DOI:https://doi.org/10.1103/PhysRevB.80.125205
©2009 American Physical Society