Thermoelectric properties of IrSb₃ and related ternary skutterudite system

The binary antimonide compounds with the skuttemdite structure have a potential for thermoelectric applications because of the high carrier mobility, high thermoelectric power, and relatively low thermal conductivity due to the complex crystal structure. However, the room temperature thermal conductivity of these skutterudite materials is as high as about 10W/mK with an estimated 80-90% contribution from the lattice thermal conductivity. Because the lattice thermal conductivity of related ternary skutterudite compounds can be substantially reduced due to the additional phonon scattering, a study of thermoelectric properties of these compounds is of interest. The binary IrSb₃, ternary Ir_1-xRu_xSb₃, and Ir(M_xSb_1-x)₃ (M=Ge, Sn) compounds were prepared by hot pressing of pre-reacted powders. We have measured the electrical resistivity, thermoelectric power, and thermal conductivity, in a temperature range from room temperature to 973K. The binary kSb₃ compound is found to have P-type electrical properties exhibiting a good Seebeck coefficient(up to 225μV/K around 773K), electrical resistivity(5×10^-5Ohm M around 933K), and relatively low thermal conductivity(6W/mK around 950K). The lattice thermal conductivity, κ_lat was calculated from the Wiedemann-Franz relationship.