半赫斯勒材料同時具有優異的熱電性能和力學性能，是一種良好的能源轉化材料，有潛力開發先進的熱電器件，目前制約其發展的主要阻礙是其固有的脆性以及有限的延展性。

而在面心立方結構中存在的剪切誘導“抓緊鍵”現象，能夠使材料表現出良好的延展性，而半赫斯勒材料的晶體結構是三層嵌套的面心立方結構，其晶體結構中可能同樣存在剪切誘導“抓緊鍵”現象，使其具有潛在優異的延展性。

Fig. 2 | The atomic configurations and dynamic?chemical bonds length of TaFeSb before first stress?releasing process during the (111)/<–1-12> shear.

來自武漢理工大學理學院的李國棟教授團隊，使用第一性原理方法研究了TaFeSb半赫斯勒熱電材料的剪切響應，發現了剪切誘導“抓緊鍵”現象，該“抓緊鍵”現象被認為是不全位錯導致的連續滑移，使材料具有良好的延展性。

該團隊除研究了TaFeSb的剪切響應外，還在具有相同結構特征的NbFeSb中同樣發現了剪切誘導“抓緊鍵”現象，而在SnNiY (Y = Ti, Zr, Hf)的剪切響應中，晶體結構逐漸軟化來釋放應力，兩者的差異來源于是否發生晶面解離。

Fig. 4 | The generalized stacking fault energy calculations?model and generalized stacking fault?energy results of TaFeSb.

最終，剪切誘導“抓緊鍵”現象被認為是晶體結構沿特定滑移面發生化學鍵斷裂后出現的連續滑移。作者的此項工作揭示了半赫斯勒熱電材料潛在的延展性及其本質。相關論文近期發表于npj Computational Materials 10:?61 (2024)。

Fig. 5 | The atomic configurations and dynamic?chemical bonds length of SnNiTi before first stress?releasing process during the (111)/<–1-12> shear.

Editorial Summary

Half-Heusler materials, with excellent thermoelectric and mechanical properties, are one kinds of excellent energy conversion materials, which is potential on developing advanced thermoelectric devices. At present, the main obstacle to their development is their inherent brittleness and limited ductility. Shear induced “catching bonds” phenomenon has been discovered in face-centered cubic structure, resulting in the excellent ductility. Half-Heusler materials with face-centered cubic sub-lattices may possess shear induced “catching bonds” phenomenon, resulting in the potential excellent ductility.

Fig. 6 | Shear strain dependent relative systematic?energy of XFeSb (X = Nb, Ta) and SnNiY (Y = Ti,?Zr, Hf) during the (111)/<–1-12> shear.

A research group led by Professor Guodong Li, from the School of Science at Wuhan University of Technology, used the first-principles calculations investigating the shear response of TaFeSb half-Heusler thermoelectric materials and found the shear induced “catching bonds” phenomenon during the shear process, resulting in the excellent ductility. Such shear induced “catching bonds” phenomenon can be considered as the continuous slips caused by partial dislocations. In addition to the investigations on the shear response of TaFeSb, shear-induced “catching bonds” phenomenon have also been found in NbFeSb with the same structural characteristics, while in the shear response of SnNiY (Y = Ti, Zr, Hf), the crystal structures gradually soften to release the stress, whose difference comes from whether the crystal plane cleavage occurs. Finally, the shear-induced “catching bonds” phenomenon can be considered as the continuous slips that occur after the chemical bond breakage along the specific crystal plane.

The research group revealed the potential ductility of the halfi-Heusler thermoelectric material combined with its essence and origin . The relevant work was recently published in npj Computational Materials 10: 61 (2024).

原文Abstract及其翻譯

Haoqin Ma, Xiege Huang, Zhongtao Lu, Xiaobin Feng, Bo Duan,?Wenjuan Li, Yinhan Liu, Pengcheng Zhai, Guodong Li, Qingjie Zhang

Abstract?Half Heusler materials exhibit excellent thermoelectric and mechanical properties, rendering them potential candidates for advanced thermoelectric devices. Currently, the developments on interrelated devices are impeded by their inherent brittleness and limited ductility. Nevertheless, it exists the potential ductility on half Heusler materials with face-centered cubic sub-lattices through the expectation on the occurrence of shear induced ‘catching bonds’ which can result in excellent ductility on other face centered cubic materials. In this work, focus on half Heusler thermoelectric materials XFeSb (X = Nb, Ta) and SnNiY (Y = Ti, Zr, Hf), the shear deformation failure processes are deeply investigated through the first principle calculations. Shear induced ‘catching bonds’ are found on XFeSb (X = Nb, Ta) along the (111)/<-1-12> slip system, which releasing the internal stress and exactly resulting in the potential ductility. According to the thermodynamic criterion based on generalized stacking fault energy, the essence of shear induced ‘catching bonds’ are interpreted as the (111)/<-110> slips formed by several 1/3(111)/<-1-12> partial dislocations motions. During the (111)/<-1-12> shear on SnNiY (Y = Ti, Zr, Hf), the structural integrity is maintained without inducing ‘catching bonds’. Different deformation processes occurred in the identical crystal structure are elucidated through the energy explanation, revealing that shear induced ‘catching bonds’ originate from the crystal plane cleavage on the (111) plane. The present works offer significant advantageous for the assessment and comprehension of shear induced ‘catching bonds’ in other materials, and facilitate the developments of XFeSb (X = Nb, Ta)-based thermoelectric devices with excellent ductility.

摘要半赫斯勒材料具有優異的熱電性能和力學性能，有潛力開發先進的熱電器件，目前制約其器件發展的主要阻礙是其固有的脆性以及有限的延展性。在面心立方結構中存在的剪切誘導“抓緊鍵”現象，能夠使材料表現出良好的延展性，而半赫斯勒材料的晶體結構是三層嵌套的面心立方結構，其晶體結構中可能也同樣存在剪切誘導“抓緊鍵”現象，使其具有潛在優異的延展性。本文以半赫斯勒熱電材料XFeSb (X = Nb, Ta)和SnNiY (Y = Ti, Zr, Hf)作為研究對象，通過第一性原理方法研究了其剪切變形失效過程。XFeSb (X = Nb, Ta)沿(111)/<-1-12>滑移系剪切時出現了剪切誘導“捕獲鍵”現象，釋放了內應力，從而使材料具有潛在的延展性。基于廣義堆垛層錯能的熱動力學準則，該剪切誘導“抓緊鍵”現象被認為是1/3(111)/<-1-12>不全位錯運動形成的(111)/<-110>滑移。在SnNiY (Y = Ti, Zr, Hf)沿(111)/<-1-12>滑移系剪切的過程中，結構始終保持完整性，不會產生剪切誘導“抓緊鍵”現象。通過能量解釋，揭示了剪切誘導“抓緊鍵”現象源于(111)平面上的晶面解理。本研究為評估和理解其他材料中的剪切誘導“抓緊鍵”現象提供了理論基礎，并促進了具有優異延展性的XFeSb (X = Nb, Ta)基熱電器件的開發。