Liu Yinqiao, Jiang Zhou, Jiang Xue, Zhao Jijun
Key Laboratory of Material Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education Dalian 116024 China
RSC Adv. 2020 Jul 8;10(43):25836-25847. doi: 10.1039/d0ra04385k. eCollection 2020 Jul 3.
Since MAB (where M is a transition metal, A is an groups 13-16 element, and B is boron) phases possess good electrical conductivity, high-temperature oxidation and shock resistance, it is meaningful to develop a database to help us figure out optimal compositions and further promote their applications. In this paper, we screened and studied all the available MABs with the M-site being one of the 3d, 4d, or 5d transition metals by using an method. Among them, 23 MAB phases of MAlB (222-MAB phases with M = Ti, V, Nb, Ta, Cr, Mo, W, Mn, and Tc) and MAlB (212-MAB phases with M = Sc, Ti, Zr, Hf, V, Nb, Cr, Mo, W, Mn, Tc, Fe, Co, and Ni) stand out in terms of structural stability and their electronic, mechanical, optical and thermodynamic properties have been investigated. For both types of MAB phases early transition elements are more feasible to synthesize than post transition elements, because of the lower number of valence electrons and lower formation energy. The effect of valence electron concentration and composition of MAB compounds could also enable fine tuning of their mechanical properties. The bulk modulus, shear modulus, and Young's modulus of the 222-MAB phases are in the range of 145-233 GPa, 101-145 GPa, and 252-361 GPa, respectively, while they are 152-262 GPa, 91-177 GPa, and 237-422 GPa for the 212-MAB phases, respectively. Their mechanical ductilities also show strong valence electron number dependency, with their maximum value occurring at NiAlB and CoAlB, respectively. More interestingly, a low thermal expansion coefficient and good high temperature strength have also been found in those MAB phases, which are favorable for their potential applications as refractory materials. In addition, the possibility of forming new two-dimensional (2D) materials from layered MAB phases, termed MBenes, is predicted by investigating the interplay of the tensile strain, complex chemical bonding and exfoliation energy.
由于MAB相（其中M为过渡金属，A为13 - 16族元素，B为硼）具有良好的导电性、高温抗氧化性和抗冲击性，因此开发一个数据库来帮助我们找出最佳成分并进一步推广其应用具有重要意义。在本文中，我们使用一种方法筛选并研究了所有可用的MAB，其中M位为3d、4d或5d过渡金属之一。其中，MAlB的23个MAB相（M = Ti、V、Nb、Ta、Cr、Mo、W、Mn和Tc的222 - MAB相）以及MAlB（M = Sc、Ti、Zr、Hf、V、Nb、Cr、Mo、W、Mn、Tc、Fe、Co和Ni的212 - MAB相）在结构稳定性方面表现突出，并且对它们的电子、机械、光学和热力学性质进行了研究。对于这两种类型的MAB相，早期过渡元素比后期过渡元素更易于合成，这是因为价电子数较少且形成能较低。MAB化合物的价电子浓度和组成的影响也可以对其机械性能进行微调。222 - MAB相的体积模量、剪切模量和杨氏模量分别在145 - 233 GPa、101 - 145 GPa和252 - 361 GPa范围内，而212 - MAB相的这些模量分别为152 - 262 GPa、91 - 177 GPa和237 - 422 GPa。它们的机械延展性也表现出对价电子数的强烈依赖性，其最大值分别出现在NiAlB和CoAlB中。更有趣的是，在这些MAB相中还发现了低热膨胀系数和良好的高温强度，这有利于它们作为耐火材料的潜在应用。此外，通过研究拉伸应变、复杂化学键和剥离能之间的相互作用，预测了由层状MAB相形成新型二维（2D）材料（称为MBenes）的可能性。
