Advanced Half-Heusler Thermoelectric Materials (AHHTM)

• Applicants: Professorin Dr. Claudia Felser, since 10/2020; Privatdozent Dr. Thomas Gruhn; Professorin Dr. Anke Weidenkaff, since 6/2019
• Subject Area: Synthesis and Properties of Functional Materials
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 392228380

Thermoelectric devices can be used for the construction of renewable energy sources that can provide important contributions to an eco-friendly energy supply. Because of their reliability, compactness and ease of maintenance, they are of great relevance for waste heat utilization, especially for exhaust heat in cars, but also as outer space power supply. Half-Heusler compounds are novel and environmentally friendly high temperature thermoelectric materials with abundant composition elements, excellent mechanical properties and thermal stability. In this joint Sino-German research project, five institutions from both China and Germany collaboratively work on this important thermoelectric materials system. Three typical half-Heusler compounds, e.i. ZrNiSn-, ZrCoSb-, and NbFeSb- based compounds, are mainly focused. Two fundamental scientific issues of half-Heusler thermoelectric materials will be studied in our project: a) We will investigate intrinsic reasons leading to the excellent power factor of half-Heusler materials and how they can be further enhanced. b) We will study the influence of multiscale phonon scattering sources on thermal conductivity and find optimal ways to suppress the heat transport. The topics will be investigated through the combination of ab-initio calculation, modeling analysis and experimental exploration. Firstly, we will use ab-initio calculations to explore and deeply understand the intrinsic electronic and phonon structures of pure and alloyed half-Heusler compounds. Furthermore, low temperature electrical and thermal transport of single crystal and polycrystalline half-Heusler compounds will be investigated and modeled to get a detailed understanding of the electron and phonon scattering mechanisms. Here, we will consider scattering from intrinsic defects, from domain boundaries in phase-separated Half-Heusler alloys and from grain boundaries and search for a synergistic combination that maximally suppresses the heat conductivity. Thirdly, based on the obtained results from ab-initio calculations and low temperature investigations, new strategies concerning band engineering and multiscale phonon scattering engineering will be explored to further improve the high temperature thermoelectric performance of half-Heusler compounds. The relationship between materials fabrication, microstructure and transport properties will be studied. Finally, half-Heusler thermoelectric modules will be assembled, tested and numerically analyzed, which will provide significant guidelines for large-scale application of this environmentally friendly high temperature thermoelectric materials system.

• DFG Programme: Research Grants
• International Connection: China
• Partner Organisation: National Natural Science Foundation of China
• Cooperation Partners: Professor Dr. Jiong Yang; Professor Dr. Xinbing Zhao; Professor Dr. Tiejun Zhu
• Ehemalige Antragsteller: Privatdozent Dr. Benjamin Balke, until 6/2019; Dr. Chenguang Fu, until 10/2020