Improved figure of merit (z) at low temperatures for superior thermoelectric cooling in Mg3(Bi,Sb)2

• Published in: Nature communications Vol. 14; no. 1; pp. 4932 - 9
• Main Authors: Chen, Nan, Zhu, Hangtian, Li, Guodong, Fan, Zhen, Zhang, Xiaofan, Yang, Jiawei, Lu, Tianbo, Liu, Qiulin, Wu, Xiaowei, Yao, Yuan, Shi, Youguo, Zhao, Huaizhou
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 15.08.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 147/135; 147/137; 639/301/119/995; 639/301/299/2736; Antimony; Bismuth; Boundaries; Carrier mobility; Cooling; Crucibles; Crystal growth; Crystals; Electron transport; Figure of merit; Grain boundaries; Grain growth; Grain size; High temperature; Humanities and Social Sciences; Low temperature; Magnesium base alloys; Mobility; Modules; multidisciplinary; Room temperature; Scattering; Science; Science (multidisciplinary); Thermoelectric cooling
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-40648-5

The low-temperature thermoelectric performance of Bi-rich n-type Mg 3 (Bi,Sb) 2 was limited by the electron transport scattering at grain boundaries, while removing grain boundaries and bulk crystal growth of Mg-based Zintl phases are challenging due to the volatilities of elemental reactants and their severe corrosions to crucibles at elevated temperatures. Herein, for the first time, we reported a facile growth of coarse-grained Mg 3 Bi 2- x Sb x crystals with an average grain size of ~800 μm, leading to a high carrier mobility of 210 cm 2  · V −1  · s −1 and a high z of 2.9 × 10 −3  K −1 at 300 K. A Δ T of 68 K at T h of 300 K, and a power generation efficiency of 5.8% below 450 K have been demonstrated for Mg 3 Bi 1.5 Sb 0.5 - and Mg 3 Bi 1.25 Sb 0.75 -based thermoelectric modules, respectively, which represent the cutting-edge advances in the near-room temperature thermoelectrics. In addition, the developed grain growth approach can be potentially extended to broad Zintl phases and other Mg-based alloys and compounds. It is challenging to increase carrier mobility in n-type Mg 3 (Bi,Sb) 2 due to grain-boundary scattering. Here, authors reported a facile growth of coarse-grained Mg 3 (Bi,Sb) 2 crystals with high carrier mobility. The as-fabricated module shows cooling performance comparable to commercial Bi 2 Te 3 module.