Maximizing thermoelectric performance of AgPbmSbTem+2 by optimizing spark plasma sintering temperature

AgPbmSbTem+2 (abbreviation as LAST) is a promising thermoelectric material based on PbTe for mid-temperature applications. The electrical and thermal transport properties of LAST alloys are greatly affected by the formation of nanostructured precipitation depending on the processing conditions, especially for spark plasma sintering (SPS) combined with mechanical alloying (MA). This study was focused on the optimization of SPS temperature (TSPS) and found that its variation in a narrow range (100 K) leads to apparent differences of thermoelectric performances. The sample sintered at an optimized temperature (TSPS = 923 K) shows a low κtotal (0.829 Wm−1K−1) and a high PF (14.9 Wm−1K−2), which is mainly attributed to the nanoscale composition segregation of Ag and Sb. The highest ZT value of 1.28 at 773 K was obtained when TSPS = 923 K, along with the highest ZTeng value of 0.26 and the corresponding ηmax value of 5.8% at the range of 323 K (Tcold)-773 K (Thot), which were increased almost twice by the optimization of sintering temperature.