Influence of Ir substitution on the thermoelectric properties of Ba _0.3(Ir_xCo_1-x)₄Sb₁₂ solid solutions

Polycrystalline skutterudite solid solutions, Ba_0.3 (Ir _xCo_1-x)₄Sb₁₂ (x from 0 to 0.11), have been synthesized by a two-step solid state reaction method and sintered by a spark plasma sintering (SPS) technique. The influence of Ir substitution on electrical and thermal transport properties has been investigated in the temperature range of 300-850 K. Through Ir substitution, the lattice thermal conductivity was depressed due to the phonon scattering by point defects. The thermopower and thermoelectric power factor increased because of the enhancement of carrier acoustic lattice scattering especially at lower temperatures. Both the dimensionless figure of merit (ZT) and the thermoelectric compatibility factor (C_F), which play very important roles for applications, were improved over the whole temperature region.