Electronic Transport Properties of Ni-doped CoSb3 Prepared by Encapsulated Induction Melting

Ni-doped CoSb₃ 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. Carrier concentration increased with increasing the Ni doping content and the Ni dopants could generate excess electrons. However, carrier mobility decreased with increasing the doping content, which indicates that the electron mean free path was reduced by the impurity scattering. Seebeck coefficient and electrical resistivity decreased with increasing the carrier concentration because the increase in carrier concentration by doping overcame the decrease in carrier mobility by the impurity scattering. Seebeck coefficient showed a negative value at all temperatures examined and it increased as the temperature increased. Temperature dependence of electrical resistivity suggested that Co_1-xNi_xSb₃ is a highly degenerate semiconducting material. Thermal conductivity was considerably reduced by Ni doping and the lattice contribution was dominant in the Ni-doped CoSb₃