Approaching the minimum lattice thermal conductivity of p-type SnTe thermoelectric materials by Sb and Mg alloying

SnTe,as the nontoxic analogue to high-performance PbTe thermoelectric material,has captured the worldwide interest recently.Many triumphant instances focus on the strategies of band convergence,resonant doping,and nano-precipitates phonon scattering.Herein,the p-type SnTe-based materials SnSbMgTe(x=0–0.10)are fabricated and a combined effect of Sb and Mg is investigated.Sb alloying tunes the hole carrier concentration of SnTe and decreases the lattice thermal conductivity.Mg alloying leads to a nearly hundredfold rise of disorder parameter due to the large mass and strain fluctuations,and as a consequence the lattice thermal conductivity decreases further down to$0.64 W mKat 773 K,close to the theoretical minimum of the lattice thermal conductivity($0.50 W mK)of SnTe.In conjunction with the enhancement of the Seebeck coefficient caused by band convergence due to Mg alloying,the maximum zTreaches$1.02 and the device zTof$0.50 at 773 K for SnSbMgTe,suggesting this SnTe-based composition has a promising potential in intermediate temperature thermoelectric applications.