Mechanical behavior of planar borophenes: A molecular mechanics study

Abstract

The aim of the present work is to provide numerical data regarding the in-plane tensile mechanical response of two-dimensional boron sheets known as borophene sheets or borophenes. The proposed theoretical approach is grounded in a molecular mechanics method which utilizes the equilibrium atomistic structure of the nanomaterials under investigation. In addition, it incorporates special spring-like finite elements to approximate the interatomic force field. The computational approach is mainly based on the modified Morse interatomic potential. Some of the relevant force field parameters concerning boron element are estimated according to the universal force field. Four different atomistic configurations of borophene monolayers are analyzed, i.e., an ideal perfect sheet exclusively made from regular triangular motifs, a sheet made from the ideal structure of the B36 molecule, a sheet known as “α” containing uniformly distributed regular hexagonal holes, and a sheet known as “β” having hexagonal holes distributed in lines. The four tested sheets are selected to have an almost square shape of the same size. Based on the computed tensile stress-strain curves, several mechanical properties along the zigzag and armchair directions are estimated. The Young’s modulus, Poisson’s ratio, tensile strength and failure strain of the borophenes are illustrated with respect to the hexagonal hole density. Comparisons are made where possible.