Journal Article

Plasticity in single-crystalline Mg3Bi2 thermoelectric material

Mu, Huimin, Hou, Shuaihang, Xie, Guoqiang, Wang, Xiaodong, Mao, Jun, Wang, Yumei, Zhang, Qian, Zhao, Lijia, Xue, Wenhua, Ma, Xiaojing, Zhang, Yue, Cao, Feng, Qiu, Jiamin, Ye, Sheng, Cheng, Jinxuan, Zhao, Peng, Zhang, Tianyu, Fu, Yuhao, Zhi, Shizhen, Liu, Xingjun

2024

Overview

Most of the state-of-the-art thermoelectric materials are inorganic semiconductors. Owing to the directional covalent bonding, they usually show limited plasticity at room temperature 1 , 2 , for example, with a tensile strain of less than five per cent. Here we discover that single-crystalline Mg 3 Bi 2 shows a room-temperature tensile strain of up to 100 per cent when the tension is applied along the (0001) plane (that is, the a b plane). Such a value is at least one order of magnitude higher than that of traditional thermoelectric materials and outperforms many metals that crystallize in a similar structure. Experimentally, slip bands and dislocations are identified in the deformed Mg 3 Bi 2 , indicating the gliding of dislocations as the microscopic mechanism of plastic deformation. Analysis of chemical bonding reveals multiple planes with low slipping barrier energy, suggesting the existence of several slip systems in Mg 3 Bi 2 . In addition, continuous dynamic bonding during the slipping process prevents the cleavage of the atomic plane, thus sustaining a large plastic deformation. Importantly, the tellurium-doped single-crystalline Mg 3 Bi 2 shows a power factor of about 55 microwatts per centimetre per kelvin squared and a figure of merit of about 0.65 at room temperature along the a b plane, which outperforms the existing ductile thermoelectric materials 3 , 4 . The thermoelectric material Mg 3 Bi 2 is shown to be ductile in single-crystal form along certain directions, with a room-temperature tensile strain of 100%, which is attributed to the gliding of dislocations.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 119/118 / 639/301/299/2736 / 639/4077/4107 / Banded structure / Chemical bonds / Crystal dislocations / Deformation analysis / Deformation mechanisms / Dislocation / Edge dislocations / Energy / Figure of merit / Gliding / Humanities and Social Sciences / Metals / multidisciplinary / Plastic deformation / Plastic properties / Plasticity / Power factor / Room temperature / Science / Science (multidisciplinary) / Semiconductors / Shear stress / Single crystals / Stress-strain curves / Tellurium / Tensile strain / Thermoelectric materials