Thermoelectric properties of CoSb3 with dispersed FeSb2 particles

We have prepared a sintered CoSb3-FeSb2 composite where the FeSb2 particles are dispersed in the CoSb3 matrix by mechanical grinding (MG) and hot pressing, and investigated the Seebeck coefficient, electrical resistivity, and thermal conductivity in order to estimate the corresponding figure of merit. The thermal conductivity of the composite is lower than that of CoSb3. The electrical resistivity of the composite increases with increasing MG time, but it is lower than that of CoSb3 at high temperature. The decrease in the thermal conductivity and the lesser increase in the electrical resistivity are ascribed to the enhancement of phonon scattering caused by the dispersion of FeSb2 particles in the CoSb3 matrix and the low electrical resistivity of FeSb2, respectively. As a result, the composite whose molar ratio of CoSb3 to FeSb2 is 0.7:0.3 and the MG time is 25 h has a maximum figure of merit value of 6.1x10(-4) K-1 at 756 K. This value is much larger than the maximum value of CoSb3 at 482 K of 3.2x10(-4) K-1. (C) 2000 American Institute of Physics. [S0021-8979(00)00718-0].