Thermoelectric Properties of xPbTe/Yb _0.2Co ₄Sb ₁₂ Hot-Pressed Samples

The xPbTe/Yb _0.2Co ₄Sb ₁₂ compounds were prepared by the ball-milling and hot-pressed process. Electrical conductivity of the composite samples are reduced with a increase in PbTe content; and, their temperature dependence coefficients show the positive values. The maximum electrical conductivity of composite materials is ~80000 Sm ^-1 at 800 K. The Seebeck coefficient (absolute value) of the composite material is obviously improved with an increase in the dispersed phase (PbTe) content; the Seebeck coefficient (absolute value) of the 10PbTe sample is ~260 μVK ^-1 at 700 K, which increases by 13.6% relative to that of the Yb _0.2Co ₄Sb ₁₂ sample. The thermal conductivity of the composite samples is improved due to introduction of PbTe, and the thermal conductivity of the 10PbTe sample is ~3 Wm ^-1K ^-1 at 550 K. The maximum value of ZT is 0.78 at 700 K for the 2.5PbTe sample.