Optimization of the thermoelectric performance of α-MgAgSb-based materials by Zn-doping

Recently, α-MgAgSb-based materials have proved to be a kind of potential thermoelectric materials around room temperature. Here, a series of Zn-doped α-MgAgSb have been successfully synthesized by high-temperature milting and spark plasma sintering combined with annealing. Effect of Zn-doping on the microstructure and thermoelectric performance of α-MgAgSb has been investigated. Results show that Zn-doping can enhance the crystallization and carrier concentration, resulting in an increased electrical performance. Simultaneously, multiscales of nanodots, defects, grain boundaries and impurities have been introduced to reduce the lattice thermal performance. Finally, both the optimized electrical and thermal properties significantly promote the thermoelectric performance. A peak ZT of 1.29 has achieved for Mg_0.985Zn_0.015Ag_0.97Sb_0.99 at 550 K, about 18% higher than MgAg_0.97Sb_0.99, which indicates that Zn-doping into Mg-site is beneficial to optimize the performance of α-MgAgSb-based thermoelectric materials.