Thermoelectric properties enhancement of Ba0.2Co4Sb12 through dispersion of GaSb inclusions

The combined effects of Ba-filling the voids and GaSb nanophase incorporation in the matrix of Co4Sb12 have been studied for thermoelectric properties. High energy ball-milling was used to disperse GaSb in Ba0.2Co4Sb12. A slight off-stoichiometry between Co and Sb generated CoSb2 and CoSb phases. Electron back-scattered diffraction showed nanocrystalline (50-200 nm) GaSb grains uniformly distributed on the matrix along with a few large grains (1-3 mu m). The low electrical resistivity (rho) of Ba0.2Co4Sb12 can be attributed to the +2 oxidation state of Ba. The increase in. of composites occurred due to the enhanced scattering of charge carriers at interfaces. No significant change in Seebeck coefficients was found in composites. The simultaneous effect of anharmonicity induced by Ba-filler in the voids and the enhanced interfaces between GaSb and the matrix reduced lattice thermal conductivity and brought about an improvement in zT from 0.75 to similar to 1.0 for (GaSb) 0.4+Ba0.2Co4Sb12 at 773 K.

Automated summary

The combination of Ba-filling the voids and GaSb nanophase incorporation in Co4Sb12 matrix resulted in improved thermoelectric properties, mainly by reducing lattice thermal conductivity and enhancing scattering effect to enhance zT.