In Situ Reaction Induced Core-Shell Structure to Ultralow κlat and High Thermoelectric Performance of SnTe

Lead-free chalcogenide SnTe has been demonstrated to be an efficient medium temperature thermoelectric (TE) material. However, high intrinsic Sn vacancies as well as high thermal conductivity devalue its performance. Here, beta-Zn4Sb3 is incorporated into the SnTe matrix to regulate the thermoelectric performance of SnTe. Sequential in situ reactions take place between the beta-Zn4Sb3 additive and SnTe matrix, and an interesting "core-shell" microstructure (Sb@ZnTe) is obtained; the composition of SnTe matrix is also tuned and thus Sn vacancies are compensated effectively. Benefitting from the synergistic effect of the in situ reactions, an ultralow kappa(lat) approximate to 0.48 W m(-1) K-1 at 873 K is obtained and the carrier concentrations and electrical properties are also improved successfully. Finally, a maximum ZT approximate to 1.32, which increases by approximate to 220% over the pristine SnTe, is achieved in the SnTe-1.5% beta-Zn4Sb3 sample at 873 K. This work provides a new strategy to regulate the TE performance of SnTe and also offers a new insight to other related thermoelectric materials.