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

Fe-doped CoSb₃ skutterudites were prepared by encapsulated induction melting and their thermoelectric and electronic transport properties were investigated. The positive signs of Seebeck and Hall coefficients for all Fe-doped specimens revealed that Fe atoms successfully acted as p-type dopants by substituting Co atoms. Carrier concentration increased with increasing the Fe doping content and the Fe dopants could affect the electronic structure of CoSb₃ and generate excess holes. However, carrier mobility decreased with increasing the doping content, which indicates that the hole mean free path was reduced by the impurity scattering. Seebeck coefficient and electrical resistivity were almost independent of carrier concentration between 5.1times10¹⁸ and 1.2times10²⁰/cm³ because the increase in carrier concentration by doping was competitive with the decrease in carrier mobility by the impurity scattering. Seebeck coefficient showed a positive value at all temperatures examined and it increased as the temperature increased. Temperature dependence of electrical resistivity suggested that Co_1-xFe_xSb₃ is a highly degenerate semiconducting material. Thermal conductivity was considerably reduced by Fe doping and the lattice contribution was dominant in the Fe-doped CoSb₃ skutterudites