Zhao Xin, Nguyen Manh Cuong, Wang Cai-Zhuang, Ho Kai-Ming
Ames Laboratory, US DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
J Phys Condens Matter. 2014 Nov 12;26(45):455401. doi: 10.1088/0953-8984/26/45/455401. Epub 2014 Oct 16.
As a distinct class of ultra-hard materials, transition metal borides are found to have superior mechanical properties that challenge the traditional materials. In this work, we explored new stable structures for rhenium borides with different stoichiometries using genetic algorithm in combination with first-principles calculations. Based on theoretical calculations, ReB in a P-3m1 structure is found to be stable against decomposition reactions below 10 GPa and ReB3 in a P-6m2 structure is stable above 22 GPa. Two new phases of Re(2)B are predicted to be thermodynamically stable at pressures higher than 55 GPa and 80 GPa respectively. We also show that a C2/m structure discovered for ReB(4) has energy lower than that of the R-3m structure reported earlier (Wang et al 2013 J. Alloys Compd. 573 20). Elastic and vibrational properties from first-principles calculations indicate that the low-energy structures obtained in our search are mechanically and dynamically stable and are promising targets as new ultra-hard materials.
作为一类独特的超硬材料，过渡金属硼化物具有卓越的机械性能，对传统材料构成了挑战。在这项工作中，我们结合遗传算法和第一性原理计算，探索了不同化学计量比的铼硼化物的新稳定结构。基于理论计算，发现P-3m1结构的ReB在低于10 GPa时对分解反应稳定，P-6m2结构的ReB3在高于22 GPa时稳定。预测Re(2)B的两个新相分别在高于55 GPa和80 GPa的压力下热力学稳定。我们还表明，发现的ReB(4)的C2/m结构的能量低于先前报道的R-3m结构（Wang等人，2013年，《合金与化合物杂志》，573卷，20页）。第一性原理计算得到的弹性和振动性能表明，我们搜索得到的低能量结构在机械和动力学上是稳定的，有望成为新型超硬材料的目标。
