Composition optimization of p-type AgSnmSbTem+2 thermoelectric materials synthesized by mechanical alloying and spark plasma sintering

Lead-free p-type AgSnmSbTem+2 (m = 2, 4, 10, 18) compound thermo-electric materials were fabricated by a process combining mechanical alloys and spark plasma sintering. The electrical and thermal transport properties of samples with different m values in a wide range were investigated for compositional optimization with the most enhanced thermoelectric performance. It was found that both electrical and thermal conductivity increase with increasing m value, but the Seebeck coefficient shows a maximum at m = 4, resulting in an optimal composition with a relatively high thermoelectric figure of merit up to ZT ≈ 0.8 at 723 K. This work also confirmed that MA-SPS processing could be applied to the synthesis of AgSnmSbTem+2 compound thermoelectric materials.