Thermoelectric properties of Ag1−xPb18SbTe20 (x = 0, 0.1, 0.3)

Polycrystalline sintered samples of Ag1−xPb18SbTe20 (x = 0, 0.1, 0.3) were prepared by a solid-state reaction. The longitudinal and shear sound velocities were measured by an ultrasonic pulse-echo method at room temperature in order to evaluate the elastic moduli and Debye temperature. The elastic moduli and Debye temperature for Ag1−xPb18SbTe20 decrease with increasing x value. The thermal diffusivity was measured from room temperature to about 700 K. The thermal conductivity was evaluated from the thermal diffusivity and heat capacity. The value of thermal conductivity is 1.04 Wm−1 K−1 at 370 K for AgPb18SbTe20. The dimensionless figure of merit ZT of Ag1−xPb18SbTe20 was evaluated by using the data of the electrical resistivity and Seebeck coefficient obtained in the previous study. The maximum value of ZT is 0.33 at 673 K for Ag0.7Pb18SbTe20.