Anomalous temperature-dependent Young's modulus of a cast LAST (Pb-Sb-Ag-Te) thermoelectric material

摘要

Thermomechanical characterization is important to material evaluation and device design in the development of thermoelectric tech-nology. In this study, we utilize the resonant ultrasound spectroscopy (RUS) technique to examine the elastic behavior of a cast LAST (Pb-Sb-Ag-Te) material with a composition of Ag_(0.86)Pb_(19)Sb_(1.0)Te_(20) between room temperature and 823 K. The temperature-dependent Young's modulus exhibits a monotonically decreasing trend with increasing temperature. However, an abnormal slope change in the Young's modulus-temperature curve around 500 K is observed. In addition, hysteresis between heating and cooling data in the temper-ature range of 450-550 K is observed, which appears to be dependent on the heating/cooling rate during the RUS experiments such that the hysteresis disappears when the heating/cooling rate was decreased from 5 to 2 K min~(-1). In this study we propose an order-disorder transition model for the anomalous temperature-dependent Young's modulus behavior observed in this study.