Schwall Michael, Balke Benjamin
Institut für Anorganische und Analytische Chemie, Johannes Gutenberg-Universität, 55099 Mainz, Germany.
Materials (Basel). 2018 Apr 23;11(4):649. doi: 10.3390/ma11040649.
Half-Heusler compounds have been in focus as potential materials for thermoelectric energy conversion in the mid-temperature range, e.g., as in automotive or industrial waste heat recovery, for more than ten years now. Because of their mechanical and thermal stability, these compounds are advantageous for common thermoelectric materials such as Bi 2 Te 3 , SiGe, clathrates or filled skutterudites. A further advantage lies in the tunability of Heusler compounds, allowing one to avoid expensive and toxic elements. Half-Heusler compounds usually exhibit a high electrical conductivity σ , resulting in high power factors. The main drawback of half-Heusler compounds is their high lattice thermal conductivity. Here, we present a detailed study of the phase separation in an -type Heusler materials system, showing that the Ti x Zr y Hf z NiSn system is not a solid solution. We also show that this phase separation is key to the thermoelectric high efficiency of -type Heusler materials. These results strongly underline the importance of phase separation as a powerful tool for designing highly efficient materials for thermoelectric applications that fulfill the industrial demands of a thermoelectric converter.
十多年来，半赫斯勒化合物一直是中温范围内热电能量转换潜在材料的研究热点，例如用于汽车或工业废热回收。由于其机械和热稳定性，这些化合物相对于常见的热电材料如Bi 2 Te 3 、SiGe、笼状化合物或填充方钴矿具有优势。另一个优点是赫斯勒化合物具有可调节性，能够避免使用昂贵和有毒的元素。半赫斯勒化合物通常表现出高电导率σ ，从而具有高功率因数。半赫斯勒化合物的主要缺点是其高晶格热导率。在此，我们对半赫斯勒型材料体系中的相分离进行了详细研究，结果表明Ti x Zr y Hf z NiSn体系不是固溶体。我们还表明，这种相分离是半赫斯勒型材料实现热电高效率的关键。这些结果有力地强调了相分离作为一种强大工具对于设计满足热电转换器工业需求的高效热电应用材料的重要性。
