Preparation of High-Performance Mn-Doped SnTe Materials at High Pressure and High Temperature
Zelin Liu, Zhili Guo, Le Deng
Abstract
SnTe is an environmentally friendly medium-temperature thermoelectric material, but its inherent low power factor (PF) and high lattice thermal conductivity severely limit its application. In this study, based on the fact that Mn doping can induce band convergence, the high-pressure and high-temperature (HPHT) synthesis method was used to optimize the sample preparation and shorten the synthesis cycle to 30 min. The results show that the Sn 0.93 Mn 0.10 Te sample achieves the maximum PF value of 34.00 μW cm –1 K –2 at 775 K and PF ave value of 21.36 μW cm –1 K –2 between 300–875 K. Microstructure analysis shows that the high-pressure synthesis method introduces abundant grain boundaries, various grain sizes, multiple defects, and pore structures into the sample. These microscopic crystal structures can effectively scatter phonons and lower the lattice thermal conductivity. The modification of these micromorphologies results in the Sn 0.92 Mn 0.11 Te sample attaining a minimum lattice thermal conductivity of 0.45 W m –1 K –1 at 625 K. The thermoelectric figure of merit (zT) of sample Sn 0.92 Mn 0.11 Te reaches a maximum value of 1.1 at 775 K, and the zT ave reaches 0.63 in the range of 300–875 K. This study indicates that the synergistic effect of Mn element doping and microstructure modification can effectively optimize the thermoelectric transport performance of SnTe materials.