Lei Jingdan, Zhao Kunpeng, Liao Jincheng, Yang Shiqi, Zhang Ziming, Wei Tian-Ran, Qiu Pengfei, Zhu Min, Chen Lidong, Shi Xun
State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
Wuzhen Laboratory, Tongxiang, 314500, China.
Nat Commun. 2024 Aug 3;15(1):6588. doi: 10.1038/s41467-024-50946-1.
Grain boundary plays a vital role in thermoelectric transports, leading to distinct properties between single crystals and polycrystals. Manipulating the grain boundary to realize good thermoelectric properties in polycrystals similar as those of single crystals is a long-standing task, but it is quite challenging. Herein, we develop a liquid-phase sintering strategy to successfully introduce MgCu nano-sintering-aid into the grain boundaries of Mg(Bi, Sb)-based materials. The nano-aid helps to enlarge the average grain size to 23.7 μm and effectively scatter phonons, leading to excellent electrical transports similar as those of single crystals and ultralow lattice thermal conductivity as well as exceptional thermoelectric figure of merit (1.5 at 500 K) and conversion efficiency (7.4% under temperature difference of 207 K). This work provides a simple but effective strategy for the fabrication of high-performance polycrystals for large-scale applications.
晶界在热电输运中起着至关重要的作用，导致单晶和多晶之间具有不同的性质。控制晶界以在多晶中实现与单晶类似的良好热电性能是一项长期任务，但极具挑战性。在此，我们开发了一种液相烧结策略，成功地将MgCu纳米烧结助剂引入到Mg(Bi,Sb)基材料的晶界中。这种纳米助剂有助于将平均晶粒尺寸扩大到23.7μm，并有效地散射声子，从而实现与单晶类似的优异电输运、超低的晶格热导率以及出色的热电优值（500K时为1.5）和转换效率（207K温差下为7.4%）。这项工作为大规模应用制备高性能多晶提供了一种简单而有效的策略。
