Synergistic modulation of the thermoelectric performance of melt-spun p-type Mg2Sn via Na2S and Si alloying

Mg2Sn, comprising low-cost, earth-abundant and environmentally friendly elements, is a promising candidate for thermoelectric applications in a medium temperature range. In contrast to the well-developed high-performance n-type Mg2Sn materials, the thermoelectric performance of their p-type counterparts still remains much inferior. Herein, p-type Mg2Sn-based materials with combined addition of Na2S and Si have been rapidly synthesized via melt spinning and hot pressing toward enhanced thermoelectric performance from 300 K to 723 K. Detailed diffraction and microscopy characterization reveals that both Na2S and Si are alloyed into Mg2Sn, forming complete Mg2Sn-based solid solutions. The compositional modification optimizes the carrier concentration and strengthens phonon scattering, resulting in a much-enhanced power factor of 1.8 mW m(-1) K-2 at 673 K and a low total thermal conductivity of 2.0 W m(-1) K-1 at 523 K. Finally, a peak zT value of similar to 0.52 is reached in (Mg2Sn0.9Si0.1)(0.93)(Na2S)(0.07) at 673 K, which is one of the highest values for p-type Mg2Sn-based materials. This study provides an effective strategy for the synergistic modulation of electrical and thermal transport properties of p-type Mg2Sn.