Du Xiaolong, Qiu Pengfei, Chai Jun, Mao Tao, Hu Ping, Yang Jiong, Sun Yi-Yang, Shi Xun, Chen Lidong
State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
ACS Appl Mater Interfaces. 2020 Mar 18;12(11):12901-12909. doi: 10.1021/acsami.0c00321. Epub 2020 Mar 6.
β-FeSi has long been investigated as a promising thermoelectric (TE) material working at high temperatures due to its combining features of environmental friendliness, good thermal stability, and strong oxidation resistance. However, the real application of β-FeSi is still limited by its low TE figure of merit (). In this study, nearly doubled in p-type β-FeSi has been achieved via synergistically optimizing electrical and thermal transports. Based on the first-principles calculations, Al with shallow acceptor transition level and high carrier donation efficiency is chosen to dope β-FeSi. Significantly improved electrical transport, particularly in the low temperature range, has been obtained in the Al-doped β-FeSi system. The power factor for FeSiAl at 300 K is even higher than that of p-type β-FeSi-based compounds reported previously at high temperatures. By alloying β-FeSi with Os at the Fe sites, we further lower the lattice thermal conductivity. FeOsSiAl possesses the lowest lattice thermal conductivity among the β-FeSi compounds prepared by the equilibrium method. Finally, a record-high value of 0.35 is obtained for p-type FeOsSiAl. This study is expected to accelerate the application of β-FeSi.
长期以来，β-FeSi一直被作为一种很有前景的高温热电材料进行研究，因为它具有环境友好、热稳定性好和抗氧化性强等综合特性。然而，β-FeSi的实际应用仍然受到其低热电优值（）的限制。在本研究中，通过协同优化电输运和热输运，p型β-FeSi的热电优值实现了近两倍的提升。基于第一性原理计算，选择具有浅受主跃迁能级和高载流子施主效率的Al对β-FeSi进行掺杂。在Al掺杂的β-FeSi体系中，电输运得到了显著改善，尤其是在低温范围内。FeSiAl在300 K时的功率因子甚至高于之前报道的高温p型β-FeSi基化合物。通过在Fe位点将β-FeSi与Os合金化，我们进一步降低了晶格热导率。FeOsSiAl在通过平衡法制备的β-FeSi化合物中具有最低的晶格热导率。最后，p型FeOsSiAl获得了创纪录的0.35的热电优值。本研究有望加速β-FeSi的应用。
