Structural Stability and Elastic Properties of Bilayer Graphenes and Boron Nitride Nanosheets

Abstract

The bilayer structures of graphenes and boron nitride nanosheets (BNNSs) with different interlayer spacings are optimized, and their Young’s moduli are calculated using the molecular dynamics method. The optimized results indicate that the optimal interlayer distances are about 0.343 nm for bilayer graphenes and 0.354 nm for bilayer BNNSs. A comparison of the binding energy, van der Waals interactions between layers, and radial distribution function (RDF) revealed that bilayer BNNSs can achieve a more stable combined structure than bilayer graphenes. The Young’s moduli of bilayer graphenes were 1029 and 1032 GPa and those of bilayer BNNSs were 944 and 957 GPa along the zigzag and armchair directions, respectively. The moduli for the bilayer nanosheets were all slightly lower than those of the corresponding monolayer ones, wherein the reduction of BNNSs was always smaller than that of graphenes. The bilayer structure, specially bilayer graphenes, can markedly weaken the anisotropy of the elastic property. These phenomena can be rationally analyzed based on system energy, RDF, deformation electron density, and chemical bonding theory. Keywords: bilayer nanosheets, molecular dynamics, chemical bond, structural stability, elastic property.