Structure prediction, electronic, and mechanical properties of alkali metal MB_(12)(=Be, Mg, Ca, Sr) from first principles  

作　　者：Chun-Ying Pu Rong-Mei Yu Ting Wang Zhen-Yan Xüe Yong-Sheng Zhu Da-Wei Zhou 濮春英;于荣梅;王婷;薛振彦;朱永胜;周大伟(College of Physics and Electronic Engineering,Nanyang Normal University,Nanyang 473061,China;Department of Mathematics and Statistics,Nanyang Normal University,Nanyang 473061,China)

机构地区：[1]College of Physics and Electronic Engineering,Nanyang Normal University,Nanyang 473061,China [2]Department of Mathematics and Statistics,Nanyang Normal University,Nanyang 473061,China

出　　处：《Chinese Physics B》2021年第1期464-470,共7页中国物理B（英文版）

基　　金：Projected supported by the National Natural Science Foundation of China(Grant Nos.U1904179,U1904178,and 51501093);the Key Science Fund of Educational Department of Henan Province,China(Grant Nos.19A140013 and 20B140010);the Science Technology Innovation Talents Fund in Universities of Henan Province,China(Grant No.19HASTIT019)。

摘　　要：Using the particle swarm optimization algorithm on structural search methods, we focus our crystal structures search on boron-rich alkali metal compounds of MB_(12)(M = Be, Mg, Ca, Sr) with simulation cell sizes of 1–2 formula units(f.u.)at 0 GPa. The structure, electronic, and mechanical properties of MB_(12) are obtained from the density functional theory using the plane-wave pseudopotential method within the generalized gradient approximations. The formation enthalpies of MB_(12) regarding to solid metal M and solid alpha-boron suggested the predicted structures can be synthesized except for BeB12. The calculated band structures show MB_(12)(M = Be, Mg, Ca, Sr) are all indirect semiconductors. All the calculated elastic constants of MB_(12) satisfy the the mechanical stable conditions. The mechanical parameters(i.e., bulk modulus,shear modulus, and Young’s modulus) are derived using the Voigt–Reuss–Hill method. The G/B ratios indicated that the MB_(12) should exhibit brittle behavior. In addition, the hardness, Debye temperature, universal anisotropic index, and the percentage of anisotropy in compression and shear are also discussed in detail. We hope our results can inspire further experimental study on these boron-rich alkali-metal compounds.

关 键 词：first-principles calculations structure searching mechanical properties boron-rich alkali-metal compounds 

分 类 号：O614.2[理学—无机化学] TP18[理学—化学]