Analysis of the Influence of Thermal Treatment on the Stability of Ag^sub 1-x^Sb^sub 1+x^Te^sub 2+x^ and Se-Doped AgSbTe^sub 2

Issue Title: 2015 International Conference on Thermoelectrics. Guest Editors: Jihui Yang, Matt Beekman, Donald Morelli, James Salvador, David Singh, Hsin Wang, Emmanuel Guilmeau, Juri Grin, Bertrand Lenoir, Xinfeng Tang, Wenqing Zhang, Chunlei Wan, TieJun Zhu, Ryoji Funahashi, Takao Mori, Tsunehiro Takeuchi, Sabah Bux In order to systematize the knowledge on thermodynamic stability and thermoelectric properties of AgSbTe^sub 2^-based alloys, several experiments examining the influence of thermal treatment on their structural and thermoelectric properties were performed. Samples with a nominal composition of AgSbTe^sub 2^ and AgSbTe^sub 1.98^Se^sub 0.02^ were prepared and then annealed in various temperature conditions. It was confirmed that Ag^sub 1-x^Sb^sub 1+x^Te^sub 2+x^ ([beta] phase) is the only thermodynamically stable ternary compound in the Ag^sub 2^Te-Sb^sub 2^Te^sub 3^ pseudobinary system. It was also proved that thermal stability of [beta] phase is limited--it slowly decomposes below 633 K. In contrast to some reports, it was also indicated that a small amount of Se does not lead to stabilisation of AgSbTe^sub 2^ crystal structure. Despite slow kinetics of the decomposition processes, thermoelectric properties of the material are notably affected by thermal treatment and amount of Ag^sub 2^Te precipitations. Maximal ZT value of prepared materials varies from 0.65 at 575 K to 1.07 at 563 K.