Ren Qingyong, Fu Chenguang, Qiu Qinyi, Dai Shengnan, Liu Zheyuan, Masuda Takatsugu, Asai Shinichiro, Hagihala Masato, Lee Sanghyun, Torri Shuki, Kamiyama Takashi, He Lunhua, Tong Xin, Felser Claudia, Singh David J, Zhu Tiejun, Yang Jiong, Ma Jie
Key Laboratory of Artificial Structures and Quantum Control, School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, 200240, Shanghai, China.
Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, Dresden, 01187, Germany.
Nat Commun. 2020 Jun 19;11(1):3142. doi: 10.1038/s41467-020-16913-2.
Chemical doping is one of the most important strategies for tuning electrical properties of semiconductors, particularly thermoelectric materials. Generally, the main role of chemical doping lies in optimizing the carrier concentration, but there can potentially be other important effects. Here, we show that chemical doping plays multiple roles for both electron and phonon transport properties in half-Heusler thermoelectric materials. With ZrNiSn-based half-Heusler materials as an example, we use high-quality single and polycrystalline crystals, various probes, including electrical transport measurements, inelastic neutron scattering measurement, and first-principles calculations, to investigate the underlying electron-phonon interaction. We find that chemical doping brings strong screening effects to ionized impurities, grain boundary, and polar optical phonon scattering, but has negligible influence on lattice thermal conductivity. Furthermore, it is possible to establish a carrier scattering phase diagram, which can be used to select reasonable strategies for optimization of the thermoelectric performance.
化学掺杂是调节半导体尤其是热电材料电学性质的最重要策略之一。一般来说，化学掺杂的主要作用在于优化载流子浓度，但可能还存在其他重要影响。在此，我们表明化学掺杂对半赫斯勒热电材料中的电子和声子输运性质都起着多重作用。以ZrNiSn基半赫斯勒材料为例，我们使用高质量的单晶和多晶晶体，以及包括电输运测量、非弹性中子散射测量和第一性原理计算在内的各种探针，来研究潜在的电子 - 声子相互作用。我们发现化学掺杂对电离杂质、晶界和极性光学声子散射带来强烈的屏蔽效应，但对晶格热导率的影响可忽略不计。此外，有可能建立一个载流子散射相图，该相图可用于选择优化热电性能的合理策略。
