Opening Statement: Two-dimensional (2D) materials beyond graphene (e.g., hexagonal boron-nitride sheet , transition metal dichalcogenides layered structures , and phosphorene ) are receiving much attention in the post-graphene era [4,5] because of their unique electronic and optical properties and their promise in nanoscale electronic and optoelectronic applications. Other 2D materials such as silicene and germanene , which are monolyers of silicon or germanuim, respectively, have also been predicted and investegated extensively. Meanwhile, boron, a nearest-neighbor of carbon, has been considered to be possibly another element that can form 2D structures. However, in contrast to carbon, silicon, and germanium, boron is an electron-deficient element which has the tendency to form either a three-center two-electron bond or a strong directional covalent bond that give rise to various allotropic structures. In particular, 2D boron monolayer sheets (also called borophene) have been proposed recently [7-10]. Unlike B36 sheet which has a small energy gap (~0.12 eV ), all other predicted borophene are metallic and have not yet been synthesized successfully. We report here other possible allotropes of 2D boron structures that have not been predicted previously through a structural optimization technique based on a semi-empirical Hamiltonian.
Authors: M. Yu, C.B. Kah, and C.S. Jayanthi
Keywords: Boron Allotropes, Icosahedral B12 Structures, ∝-Tetragonal B50 Structures