SnTe is proposed to be an intriguing low-toxicity alternative to PbTe. Herein, we report the diminished lattice thermal conductivity (κL) and enhanced zT of SnTe by way of vacancy engineering. (SnTe)1-x(Sb2Te3)x (x = 0.03, 0.06, and 0.10) and (SnTe)1-y(Sb2Se3)y (y = 0.03 and 0.06) were synthesized by blending and sintering their solution-synthesized nano/microstructures (i.e., SnTe octahedral particles, Sb2Te3 nanoplates, and Sb2Se3 nanorods). Benefiting from the chemical reactions during sintering, single-phase SnTe-based solid solutions were formed when x or y is not higher than 0.06, into which tunable concentrations of Sn vacancies were introduced. Such vacancies significantly enhance phonon scattering, leading to the sharply reduced room temperature κL of 1.40 and 1.26 W m-1 K-1 for x = 0.06 and y = 0.06 samples, respectively, as compared to 3.73 W m-1 K-1 for pristine SnTe. Enabled by point defects with the highest concentration and SnSb2Te4 secondary phase, (SnTe)0.90(Sb2Te3)0.10 sample obtains the lowest κL of 0.70 W m-1 K-1 at 813 K. Ultimately, maximum zT values of 0.6 and 0.7 at 813 K are achieved in (SnTe)0.90(Sb2Te3)0.10 and (SnTe)0.94(Sb2Se3)0.06, respectively. This study demonstrates the effectiveness of vacancy engineering in improving zT of SnTe-based materials.
Keywords: SnTe; solvothermal synthesis; thermal conductivity; thermoelectric; vacancy engineering.