Zhang Ziye, Zhang Renqi, Qi Ning, Wu Yichu, Chen Zhiquan
Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China.
Phys Chem Chem Phys. 2020 Jul 21;22(27):15559-15566. doi: 10.1039/d0cp01231a. Epub 2020 Jul 1.
In this paper, we performed comprehensive investigations of both the thermal and electrical transport properties of BiSbSe and BiSbS by using first-principles calculations and Boltzmann transport theory. Due to the repulsion between the lone-pair electrons of Sb and the p orbital of Se(S), both BiSbSe and BiSbS show strong anharmonicity with Grüneisen parameters of 1.90 and 1.79, respectively. As a result, these two materials possess extremely low lattice thermal conductivities. Meanwhile, both BiSbSe and BiSbS exhibit similar anisotropic thermal transport behaviors, which is due to the smaller phonon group velocities along the a axis. The predicted highest ZT values at 750 K are 2.9 for n-type BiSbSe and 1.2 for p-type BiSbS. Our calculations provide insights into the origin of the extremely low thermal conductivity in BiSbSe and BiSbS, which is meaningful for exploiting high performance thermoelectric materials with low thermal conductivity.
在本文中，我们通过第一性原理计算和玻尔兹曼输运理论，对BiSbSe和BiSbS的热输运和电输运性质进行了全面研究。由于Sb的孤对电子与Se(S)的p轨道之间存在排斥作用，BiSbSe和BiSbS均表现出很强的非简谐性，其格鲁尼森参数分别为1.90和1.79。因此，这两种材料具有极低的晶格热导率。同时，BiSbSe和BiSbS都表现出相似的各向异性热输运行为，这是由于沿a轴的声子群速度较小。在750 K时，预测的n型BiSbSe的最高ZT值为2.9，p型BiSbS的最高ZT值为1.2。我们的计算为BiSbSe和BiSbS中极低热导率的起源提供了见解，这对于开发具有低热导率的高性能热电材料具有重要意义。
