Unraveling Self‐Doping Effects in Thermoelectric TiNiSn Half‐Heusler Compounds by Combined Theory and High‐Throughput Experiments
Unraveling Self‐Doping Effects in Thermoelectric TiNiSn Half‐Heusler Compounds by Combined Theory and High‐Throughput Experiments
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DOI：
10.1002/aelm.201500208
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发表时间：
2016-02
影响因子：
6.2
通讯作者：
Matthias Wambach;Robin Stern;S. Bhattacharya;P. Ziółkowski;E. Müller;G. Madsen;A. Ludwig
中科院分区：
文献类型：
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作者：
Matthias Wambach;Robin Stern;S. Bhattacharya;P. Ziółkowski;E. Müller;G. Madsen;A. Ludwig
载流子浓度的控制是优化热电功率因数的关键。它复杂地取决于主体相（此处：TiNiSn）的缺陷化学性质和由竞争相设定的边界条件。金属间半赫斯勒相TiNiSn中轻微的非化学计量的巨大影响使得组合技术非常适合系统优化其热电性能。在这项工作中，计算热化学，组合合成和高通量表征相结合，以获得一个完整的地图的热电功率因子的Ti-Ni-Sn系统。阐明了组分的化学势在确定金属间半赫斯勒相TiNiSn的详细非化学计量组成中的作用。这项工作不仅证实了关于Ni过剩的大相宽的假设，而且还证明了可以产生具有相对大的Ti过剩的TiNiSn相。这可以作为通过在三元体系Ti-Ni-Sn中自掺杂来实现高载流子浓度的新途径。载流子浓度的缺陷热化学计算结果与实验结果吻合得很好。这项工作的结果提出了改善半赫斯勒相（如TiNiSn）热电性能的新方法。
The control of the carrier concentration is a key topic in the optimization of the thermoelectric power factor. It depends intricately on the defect chemistry of a host phase (here: TiNiSn) and the boundary conditions set by competing phases. The large impact of a slight off‐stoichiometry in the intermetallic half‐Heusler phase TiNiSn makes combinatorial techniques ideally suited for systematic optimization of its thermoelectric performance. In this work, computational thermochemistry, combinatorial synthesis, and high‐throughput characterization are combined to obtain a complete map of the thermoelectric power factor for the Ti–Ni–Sn system. The role of the chemical potential of the constituents in determining the detailed nonstoichiometric composition of the intermetallic half‐Heusler phase TiNiSn is elucidated. This work not only confirms the assumption of a large phase‐width in terms of Ni surplus but also demonstrates that TiNiSn phases with a relatively large Ti surplus can be produced. This can serve as a new route for achieving high carrier concentrations by self‐doping in the ternary system Ti–Ni–Sn. The defect thermochemistry calculations for the carrier concentration are in excellent agreement with the experimental results. The findings of this work suggest new ways of improving the thermoelectric performance of half‐Heusler phases such as TiNiSn.