Synthesis and thermoelectric properties of GaxCo4Sb11.7Te0.3 skutterudites

Ga-filled and Te-doped CoSb3 skutterudites were synthesized by a melt-quench-anneal-hot-press sintering method, and their thermoelectric properties were investigated from 300 to 800 K. The filling fraction of Ga in doped skutterudite is up to x = 0.2 and the results of XRD and lattice parameter are in agreement with the change of filling fraction. When the Ga content x = 0.3, there was the second phase GaSb existing in the skutterudite. All GaxCo4Sb11.7Te0.3 samples were the N-type conduction and the electrical conductivity increased with the content of Ga increasing. Thermal conductivity of GaxCo4Sb11.7Te0.3 decreased markedly due to the phonon scattering, which resulted from the filling of Ga atoms. The highest thermoelectric figure of merit ZT = 0.6 is achieved at 650 K in the Ga0.3Co4Sb11.7Te0.3 compound.

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► Ga-filled and Te-doped CoSb3 skutterudites were synthesized.
► The filling fraction of Ga in GaxCo4Sb11.7Te0.3 skutterudite is up to x = 0.2.
► The GaSb phase existed in the skutterudite when the Ga content x = 0.3.