Electronic transport properties of InzCo4Sb12-yTey skutterudites

In_zCo₄Sb_12-yTe_y skutterudites were prepared by encapsulated induction melting and their electronic transport properties were investigated. Single phase delta-CoSb₃ was successfully obtained by the encapsulated induction melting and subsequent heat treatment at 823 K for 5 days. Te atoms acted as electron donors by substituting Sb atoms. The Hall coefficient and the Seebeck coefficient showed negative values, which confirms that In_zCo₄Sb_12-yTe_y skutterudites are n-type semiconductors. Electronic transport properties were considerably affected by Te doping rather than In filling. Carrier concentration was in the range of 7 times 10¹⁹ to 4 times 10²⁰ cm^-3, and carrier mobility was 2 to 22 cm²/Vs. The Seebeck coefficient negatively decreased and the electrical resistivity decreased by Te doping and In filling. The thermal conductivity was considerably reduced by doping as well as filling due to the phonon scattering, which is responsible for the lattice thermal conductivity reduction.