Achieving Enhanced Thermoelectric Performance in (SnTe)1-x(Sb2Te3)x and (SnTe)1-y(Sb2Se3)y Synthesized via Solvothermal Reaction and Sintering

Abstract

SnTe is proposed to be one 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, 0.10) and (SnTe)1-y(Sb2Se3)y (y = 0.03, 0.06) were synthesized by blending and sintering their solution-synthesized nano/micro-structures (i.e. SnTe octahedral particles, Sb2Te3 nanoplates, 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 W m-1 K-1 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.