Band Engineering and Phonon Engineering Effectively Improve n-Type Mg₃Sb₂ Thermoelectric Material Properties

Mg₃Sb₂-based thermoelectric materials can convert heat and electricity into each other, making them a promising class of environmentally friendly materials. Further improving the electrical performance while effectively reducing the thermal conductivity is a crucial issue. In this paper, under the guidance of the oneness principle calculation, we designed a thermoelectric Zintl phase based on Mg_3.2Sb_1.5Bi_0.5 doped with Tb and Er. Calculation results show that using Tb and Er as cationic site dopants effectively improves the electrical properties and reduces the lattice thermal conductivity. Experimental results confirmed the effectiveness of codoping and effectively enhanced thermoelectric performance. The most immense ZT value obtained by the Mg_3.185Tb_0.01Er_0.005Sb_1.5Bi_0.5 sample was 1.71. In addition, the average Young's modulus of the Mg_3.185Tb_0.01Er_0.005Sb_1.5Bi_0.5 sample is 51.85 GPa, and the Vickers hardness is 0.99 GPa. Under the same test environment, the material was subjected to 12 cycles in the temperature range of 323-723 K, and the average power factor error range was 1.8% to 2.1%, which is of practical significance for its application in actual device scenarios.