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Abstract:
The Zintl phase Sr5In2Sb6 is isostructural with Ca5In2Sb6-a promising
thermoelectric material with a peak zT of 0.7 when the carrier
concentration is optimized by doping. Density functional calculations
for Sr5In2Sb6 reveal a decreased energy gap and decreased valence band
effective mass relative to the Ca analog. Chemical bonding analysis
using the electron localizability indicator was found to support the
Zintl bonding scheme for this structure type. High temperature transport
measurements of the complete Ca5-xSrxIn2Sb6 solid solution were used to
investigate the influence of the cation site on the electronic and
thermal properties of A(5)In(2)Sb(6) compounds. Sr was shown to be fully
miscible on the Ca site. The higher density of the Sr analog leads to a
slight reduction in lattice thermal conductivity relative to Ca5In2Sb6,
and, as expected, the solid solution samples have significantly reduced
lattice thermal conductivities relative to the end member compounds.
