Low thermal conductivity in Bi–Mg co-doped SnTe material via solvothermal synthesis

There is significant interest in the utilization of inorganic materials with low thermal conductivity (κ) in thermoelectric applications. A key strategy for reducing thermal conductivity through phonon scattering is the formation of synthetic nanostructures. In this study, we synthesized pure SnTe and Bi–Mg co-doped SnTe materials via the solvothermal method. We report very low thermal conductivity of ~2.17 W m⁻¹ K⁻¹ at room temperature in pure SnTe. The notable low thermal conductivity in SnTe is mostly attributable to its nanometre-sized crystallites. Bi and Mg substitution in SnTe significantly lowers κ value from 2.17 to 0.5 W m⁻¹ K⁻¹ for Sn_0.94Bi_0.03Mg_0.03Te sample at 300 K, reducing it by ~4 times compared to pure SnTe. Point defect scattering of phonons due to Bi–Mg co-doping may also lower thermal conductivity. This study reveals a potential novel approach to achieve low thermal conductivities in SnTe through nanoscale engineering.