Roth Nikolaj, Beyer Jonas, Fischer Karl F F, Xia Kaiyang, Zhu Tiejun, Iversen Bo B
Department of Chemistry and iNano, Aarhus University Aarhus, 8000, Denmark.
State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China.
IUCrJ. 2021 Jun 30;8(Pt 4):695-702. doi: 10.1107/S2052252521005479. eCollection 2021 Jul 1.
Although crystalline solids are characterized by their periodic structures, some are only periodic on average and deviate on a local scale. Such disordered crystals with distinct local structures have unique properties arising from both collective and localized behaviour. Different local orderings can exist with identical average structures, making their differences hidden to Bragg diffraction methods. Using high-quality single-crystal X-ray diffuse scattering the local order in thermoelectric half-Heusler Nb CoSb is investigated, for which different local orderings are observed. It is shown that the vacancy distribution follows a vacancy repulsion model and the crystal composition is found always to be close to = 1/6 irrespective of nominal sample composition. However, the specific synthesis method controls the local order and thereby the thermoelectric properties thus providing a new frontier for tuning material properties.
尽管晶体固体以其周期性结构为特征，但有些晶体只是平均上具有周期性，在局部尺度上会有偏差。这种具有独特局部结构的无序晶体具有源于集体行为和局域行为的独特性质。具有相同平均结构的情况下可以存在不同的局部有序，这使得它们的差异对布拉格衍射方法来说是隐藏的。利用高质量单晶X射线漫散射研究了热电半赫斯勒合金NbCoSb中的局部有序，观察到了不同的局部有序情况。结果表明，空位分布遵循空位排斥模型，并且发现晶体组成总是接近 = 1/6，与标称样品组成无关。然而，特定的合成方法控制局部有序，从而控制热电性能，因此为调节材料性能提供了一个新的前沿领域。
