Structural Phase Transitions, Electronic Properties, and Hardness of RuB4 under High Pressure in Comparison with FeB4 and OsB4,The Journal of Physical Chemistry C

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Structural Phase Transitions, Electronic Properties, and Hardness of RuB4 under High Pressure in Comparison with FeB4 and OsB4
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2020-06-15 , DOI: 10.1021/acs.jpcc.0c03959
Komsilp Kotmool _{1,

2} , Prutthipong Tsuppayakorn-aek _{3,

4} , Thanayut Kaewmaraya , Udomsilp Pinsook _{3,

4} , Rajeev Ahuja ₅ , Thiti Bovornratanaraks _{3,

4}

Affiliation

We have employed an evolutionary algorithm with first-principles calculations to investigate the pressure-induced structural evolution of RuB₄ up to 500 GPa. The ambient phase is predicted to be a hexagonal structure (P6₃/mmc). The novel phases consisting of monoclinic (C2/c) and orthorhombic (Immm) structures are proposed to be the high-pressure phases at the pressure intervals of 198–388 GPa and beyond 388 GPa, respectively. The stability of the predicted phases is confirmed by both dynamic and elastic calculations. The electronic and mechanical properties of the predicted phases are evaluated and mainly discussed compared to the isoelectronic metal tetraborides, i.e., FeB₄ and OsB₄. In contrast to FeB₄ and OsB₄, all the stable phases of RuB₄ are metal or semimetal, and any semiconducting phases do not emerge in the transformation pathway of RuB₄. The nature of chemical bonding investigated by ELF, MPA, and pCOHP calculations reveals that the atomic configurations and the degree of covalent bonding of the predicted phases are responsible for lower hardness compared to those of FeB₄ and OsB₄. The results of this work provide more understanding of the family of metal tetraboride for designing metal-boride-based hard/superhard materials.

中文翻译：

与FeB ₄和OsB _4相比，高压下RuB _4的结构相变，电子性质和硬度

我们采用了具有第一性原理计算的演化算法，以研究压力诱导的高达500 GPa的RuB _4的结构演化。预计环境相为六方结构（P 6 ₃ / mmc）。由单斜（C 2 / c）和斜晶（Immm）组成的新相。）结构被建议为分别在198–388 GPa和超过388 GPa压力区间的高压相。预测相的稳定性通过动态和弹性计算得到确认。与等电金属四硼化物即FeB ₄和OsB ₄相比，对预测相的电子和机械性能进行了评估和讨论。与此相反的FeB ₄和OSB ₄，擦的所有稳定相₄是金属或半金属，任何半导体阶段不擦转型过程出现₄。通过ELF，MPA和pCOHP计算研究出的化学键合性质表明，与FeB ₄和OsB ₄相比，预测相的原子构型和共价键合度降低了硬度。这项工作的结果为设计基于金属硼化物的硬/超硬材料提供了对四硼化金属家族的更多了解。

更新日期：2020-07-09

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