Measurement of the intrinsic strength of crystalline and polycrystalline graphene

Abstract

The mechanical properties of materials depend strongly on crystal structure and defect configuration. Here we measure the strength of suspended single-crystal and bicrystal graphene membranes prepared by chemical vapour deposition. Membranes of interest are first characterized by transmission electron microscopy and subsequently tested using atomic force microscopy. Single-crystal membranes prepared by chemical vapour deposition show strengths comparable to previous results of single-crystal membranes prepared by mechanical exfoliation. Grain boundaries with large mismatch angles in polycrystalline specimens have higher strengths than their low angle counterparts. Remarkably, these large angle grain boundaries show strength comparable to that of single-crystal graphene. To investigate this enhanced strength, we employ aberration-corrected high-resolution transmission electron microscopy to explicitly map the atomic-scale strain fields in suspended graphene. The high strength is attributed to the presence of low atomic-scale strain in the carbon-carbon bonds at the boundary.

Polycrystalline graphene and other two-dimensional materials

“…Simulations performed on single GB models reveal that large-angle defect configurations (like those shown in the right column of Box 1) are as strong as pristine graphene, while smallangle defects characterized by larger interdislocation distances are significantly weaker 131,132 . We note that a recent nanoindentation study by Rasool et al shows a clear reduction of the fracture force when small-angle GBs are probed 133 . The computational studies also provide an insight into the atomistic picture of mechanical failure .…”

Molecular Dynamics of Cellulose Amphiphilicity at the Graphene–Water Interface

“…10 Single layer graphene has emerged, since its discovery by Geim and Noveselov, 11 as a truly remarkable material. It is known to have high strength, 12 high conductivity 13 and is relatively transparent, being only one atom thick. As a result, there is intense interest in utilizing these properties of graphene, including for devices e.g.…”

Charge and Spin Transport in Disordered Graphene-Based Materials

“…[150] The strength of individual GGBs was also found, theoretically and experimentally, to strongly depend on the misorientation angle between graphene domains. [38,175,176,177,178] However, these results are for a single GGB between two domains, and it is uncertain how they translate to macroscopic samples containing several GGBs. Moreover, the cracks that appear upon failure do not necessarily follow the GGBs but can also penetrate through the grains, [18,179] even if they originate at the GGB regions.…”

“…For example, the breaking loads for early measurements [14,174] differ significantly from those measured more recently. [177,178] In addition, as noted above, the applicability of the AFM measurements to macroscopic samples remains an open question. To finally resolve the issue, we would need a new measurement technique for estimating the elastic properties of 2D materials, which would avoid the shortcomings of the method utilizing an AFM tip.…”