Strong covalent boron bonding induced extreme hardness of VB3
Strong covalent boron bonding induced extreme hardness of VB3
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强共价硼键引起 VB3 的极高硬度
DOI：
10.1016/j.jallcom.2016.07.102
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发表时间：
2016
影响因子：
6.2
通讯作者：
Cui Tian
中科院分区：
文献类型：
--
作者：
Wei Shuli;Li Da;Lv Yunzhou;Liu Zhao;Tian Fubo;Duan Defang;Liu Bingbing;Cui Tian
富硼过渡金属钒硼化物具有优异的力学性能，是制备超硬、多功能材料的理想材料。利用第一性原理方法，在常压和高压下分别发现了两种富硼硼钒硼化物，VB 3，空间群分别为单斜C2/和正交Amm 2。C2/m-VB 3由B4单元和V2 B20单元组成，而Amm 2-VB 3由扭曲的VB 12六棱柱组成。这两个是类石墨烯硼片和过渡金属钒原子的类石墨烯结构。在21.5GPa以上，高压Amm 2-VB 3比常压C2/m-VB 3在能量上更好，并且可以淬灭到常压。在常压下，C2/m-VB 3和Amm 2-VB 3的模拟维氏硬度值分别为43.3和37.6GPa。C2/m-VB 3的高硬度归因于其晶体结构中定向褶皱的六方硼-硼网络。
Boron-rich transition metal vanadium borides have excellent mechanical properties and are favorable potential candidates for fabricating superhard, multifunctional materials. Using first-principle methodology, two boron-rich vanadium borides, VB3with monoclinicC2/mand orthorhombicAmm2 space groups, were found at ambient pressure and high pressure, respectively. TheC2/m-VB3is composed of B4units and V2B20units while theAmm2-VB3is comprised of a distorted VB12hexagonal prism. These two are sandwich-like structures of graphene-like boron sheets and transition metal vanadium atoms. The high-pressureAmm2-VB3is preferable energetically to ambient-pressureC2/m-VB3at above 21.5 GPa and can be quenched to ambient pressure. The simulated Vickers hardness values ofC2/m-VB3andAmm2-VB3are 43.3 and 37.6 GPa at ambient pressure, respectively. The higher hardness ofC2/m-VB3is attributed to the directional puckered hexagonal boron-boron network in its crystal structure.