Effects of double filling of Pb and Ba on thermoelectric properties of PbxBayCo4Sb11.5Te0.5 compounds by HPHT

Skutterudite compounds PbxBayCo4Sb11.5Te0.5 ( x ≤ 0.23 , y ≤ 0.27 ) with bcc crystal structure have been prepared by the high pressure and high temperature (HPHT) method. The study explored a chemical method for filling Pb and Ba atoms into the voids of CoSb3 to optimize the thermoelectric figure of merit Z T in the system of PbyBaxCo4Sb11.5Te0.5. The structure of PbxBayCo4Sb11.5Te0.5 skutterudites was evaluated by means of X-ray diffraction. The Seebeck coefficient, electrical resistivity and power factor were performed from room temperature to 710 K. Compared with Co4Sb11.5Te0.5, the thermal conductivity of Pb and Ba double-filled samples was reduced evidently. Among all filled samples, Pb0.03Ba0.27Co4Sb11.5Te0.5 showed the highest power factor of 31.64 μW cm−1 K−2 at 663 K. Pb0.05Ba0.25Co4Sb11.5Te0.5 showed the lowest thermal conductivity of 2.73 W m−1 K−1 at 663 K, and its maximum Z T value reached 0.63 at 673 K.