Chen Hongxiang, Yang Dongliang, Zhang Qinghua, Jin Shifeng, Guo Liwei, Deng Jun, Li Xiaodong, Chen Xiaolong
Research & Development Center for Functional Crystals, Laboratory of Advanced Materials and Electron Microscopy, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
School of Materials Science and engineering, Fujian University of Technology, Fuzhou, 350118, China.
Angew Chem Int Ed Engl. 2019 Mar 26;58(14):4576-4580. doi: 10.1002/anie.201814128. Epub 2019 Mar 3.
We report a new type of MAX phase (M=transition metals, A=main group elements, and X=C/N), Nb As C, designated as 321 phase. It differs from all the previous M AX phases in that it consists of an alternate stacking of one MX layer and two MA layers in its unit cell, while only one MA layer is allowed in usual MAX phases. The new 321 phase exhibits a bulk modulus of Nb As C up to 225(3) GPa as determined by high-pressure synchrotron X-ray diffraction, one of the highest values among MAX phases. Isostructural 321 phases V As C, Nb P C, and Ta P C are also found to exist. First-principles calculations reveal the outstanding elastic stiffness in 321 phases. Among all 321 phases, Nb P C is predicted to have the highest elastic properties. These 321 phases, represented by a chemical formula M A X, were added as new members to the MAX family and their other properties deserve future investigations.
我们报道了一种新型的MAX相（M = 过渡金属，A = 主族元素，X = C/N），即Nb₃AsC，被指定为321相。它与之前所有的MAX相不同，其晶胞由一个MX层和两个MA层交替堆叠组成，而通常的MAX相中只允许有一个MA层。通过高压同步辐射X射线衍射测定，新的321相Nb₃AsC的体模量高达225(3) GPa，是MAX相中最高值之一。还发现了同构的321相V₃AsC、Nb₃PC和Ta₃PC也存在。第一性原理计算揭示了321相具有出色的弹性刚度。在所有321相中，Nb₃PC预计具有最高的弹性性能。这些以化学式M₃AX表示的321相作为新成员被添加到MAX族中，它们的其他性质值得未来研究。
