High temperature electrical transport properties of the EuFe4Sb12 and YbFe4Sb12 filled skutterudites

Polycrystalline samples of the filled skutterudites EuFe4Sb12 and YbFe4Sb12 were prepared by direct melting and hot pressing. The samples were characterized using x-ray powder diffraction and differential thermal analysis. it was found that both compounds melt incongruently at peritectic temperatures of 1023 +/- 5 K for EuPe(4)Sb(12) and 975 +/- 5 K for YbFe4Sb12. At room temperature these materials possess a positive Seebeck coefficient of 65-67 mu V K-1 and high carrier concentration in the range 5.6 x 10(21)-3.6 x 10(21) cm(-3). The electrical transport properties were measured over the temperature range 100-860 K. For both compounds the electrical resistivity and Seebeck coefficient gradually increase with increasing temperature and for YbFe4Sb12 exhibit a maximum at 760-800 K. The estimated ZT value of YbFe4Sb12 is 0.4 at 670 K.