Electronic Transport Properties of Ni-doped CoSb_3 Prepared by Encapsulated Induction Melting

摘要

Ni-doped CoSb_3 skutterudites were prepared by encapsulated induction melting and their thermoelectric and electronic transport properties were investigated. The negative signs of Seebeck and Hall coefficients for all Ni-doped specimens revealed that Ni atoms successfully acted as n-type dopants by substituting Co atoms. The carrier concentration increased as the Ni doping content increased, and the Ni dopants could generate excess electrons. However, the carrier mobility decreased as the doping content increased, which indicates that the electron mean free path was reduced by the impurity scattering. The Seebeck coefficient and the electrical resistivity decreased as the carrier concentration increased, as the increase in carrier concentration by doping overcame the decrease in the carrier mobility by impurity scattering. The Seebeck coefficient showed a negative value at all temperatures examined and increased as the temperature increased. The temperature dependence of electrical resistivity suggested that Co_(1-x)Ni_xSb_3 is a highly degenerate semiconducting material. Thermal conductivity was considerably reduced by Ni doping, and the lattice contribution was dominant in the Ni-doped CoSb_3.