Abstract
LAST (Pb-Sb-Ag-Te) and LASTT (Pb-Sb-Ag-Te-Sn) materials exhibit good thermoelectric (TE) properties, which can be potentially applied in waste heat recovery. Thermal expansion behavior of TE materials is critical to the fabrication and performance of TE devices, which are subject to temperature gradients and/or thermal cycling under in-service conditions.
In this study, the coefficient of thermal expansion (CTE) of LAST and LASTT fabricated by both casting and hot pressing were determined via thermomechanical analysis between room temperature (RT) and 673 K. In addition, the lattice parameters of LAST materials were calculated from high temperature X-ray diffraction patterns obtained between RT and 623 K. The mean CTE values ranged between 20 x 10-6 K-1 and 23 x 10-6 K-1. While the temperature dependent CTE of Ag0.43Pb18Sb1.2Te20 composition increased with increasing temperature, a peak between RT and 450 K in the CTE versus temperature curve was observed for the Ag0.86Pb19SbTe20 concentration.
