Abstract
The interest in mechanical properties of two-dimensional materials has emerged in light of new device concepts taking advantage of flexing, adhesion and friction. Here we demonstrate an effective method to measure adhesion of graphene atop highly ordered pyrolytic graphite, utilizing atomic-scale ‘blisters' created in the top layer by neon atom intercalates. Detailed analysis of scanning tunnelling microscopy images is used to reconstruct atomic positions and the strain map within the deformed graphene layer, and demonstrate the tip-induced subsurface translation of neon atoms. We invoke an analytical model, originally devised for graphene macroscopic deformations, to determine the graphite adhesion energy of 0.221±0.011 J m−2. This value is in excellent agreement with reported macroscopic values and our atomistic simulations. This implies mechanical properties of graphene scale down to a few-nanometre length. The simplicity of our method provides a unique opportunity to investigate the local variability of nanomechanical properties in layered materials.
Highlights
The interest in mechanical properties of two-dimensional materials has emerged in light of new device concepts taking advantage of flexing, adhesion and friction
Detailed experimental analysis of these atomic blisters leads to a direct estimate of adhesion energy of B0.221 J m À 2 between the first-layer graphene and graphite bulk, which is closely comparable with the recent direct measurement of adhesion energy between mesoscopic graphite contacts[13]
The van der Waals radius is similar for both atoms[20]
Summary
The interest in mechanical properties of two-dimensional materials has emerged in light of new device concepts taking advantage of flexing, adhesion and friction. Our experimental results for adhesion energy, the local topographic characteristics of the blisters as well as the low diffusion barrier of intercalates are strongly supported by density functional theory (DFT) calculations.
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