Electronic Transport Properties of Ni-doped CoSb3 Prepared by Hot Pressing

Ni-doped CoSb3 skutterudites (Co1-xNixSb3) were prepared by hot pressing, and their electronic transport properties were examined. Single-phase delta-(Co,Ni)Sb-3 was successfully obtained, but it decomposed to gamma-(Co,Ni)Sb-2 and Sb when x >= 0.2, which means that the solubility limit of Ni in Co is x < 0.2. The negative signs of the Seebeck coefficients for all Ni-doped specimens revealed that Ni atoms acted as a-type dopants by substituting for Co atoms. The electrical resistivity and the thermal conductivity decreased with increasing Ni doping level. The ZT (dimensionless figure of merit) value was considerably enhanced by the Ni doping, and the optimum composition was found as Co0.9Ni0.1Sb3 for Ni-doped CoSb3 prepared by hot pressing.