Crystal structure modulation of SnSe thermoelectric material by AgBiSe2 solid solution.

Although low thermal conductivity and high band degeneracy bring promising thermoelectric performance to cubic SnSe, its preparation strategies remain elusive. Here, a series of Sn 1–2 x (AgBi) x Se samples are synthesized using the vacuum melting (1173 K) and spark plasma sintering (723 K) methods. Owing to the increased configurational entropy caused by AgBiSe 2 solid solution, the cubic structure is obtained when x exceeds 0.2. The optimized carrier concentration significantly enhances electrical conductivity (σ), and maximal σ of 350 Scm−1 is obtained in Sn 0.5 (AgBi) 0.25 Se. Combined with the low lattice thermal conductivity caused by the small sound velocity and strong anharmonicity, the figure of merit of 0.08 is reached in Sn 0.6 (AgBi) 0.2 Se at 500 K. The mechanical performances are also improved, and a high Vicker hardness of 1.5 GPa is obtained in Sn 0.4 (AgBi) 0.3 Se. This work demonstrates the importance of the configurational entropy in phase regulation and provides insights into the design of new thermoelectrics. [ABSTRACT FROM AUTHOR]