Intrinsic Strength and Failure Behaviors of Graphene Grain Boundaries

Abstract

As one-dimension line defects, grain boundaries (GBs) can affect many intrinsic properties of graphene. In this paper, the mechanical properties of 20 representative graphene grain boundaries were studied using density functional theory and molecular dynamics. With different arrangements of the pentagonal and heptagonal rings, the grain boundary may remain flat or become inflected up to 72°. For the flat GBs, the intrinsic tensile strength decreases linearly with the formation energy with a maximum value of 93 GPa, close to that of a perfect graphene. The intrinsic tensile strength of the inflected GBs is found to generally decrease with increasing inflection angle. Stone-Wales transformation is identified as the major failure mechanism of graphene GBs at high temperatures, whereas the initial fracture site can be either on the boundary line or inside the domain. These theoretical results constitute a useful picture of the grain boundary effect on the mechanical properties of polycrystalline graphene.

Structure of graphene and its disorders: a review

“…As large-angle GBs are able to better accommodate the stained seven-membered rings in graphene lattice, they have higher strengths than the low-angle counterparts, and even as strong as the pristine graphene structure [93]. More studies regarding the effects of grain boundaries on the mechanical properties of graphene can be found in Refs [301–304]. .…”

Structural, mechanical and electronic properties of in-plane 1T/2H phase interface of MoS2 heterostructures

“…The present results are quite different with grain boundaries effects in polycrystalline graphene, in which the ideal strength can be decreased to 20 ∼ 90% percent of the single crystal graphene. 32,34,37 …”

On Thermodynamic Stability of Hydrogenated Graphene Layers, Relevance to the Hydrogen on-board Storage

“…This is the case of existening relevant defects in graphene, i.e., in grain boundaries and/or vacancies [33][34][35][36][37][38][39][40][41][42]. This is related to further consideration of data in this analytical study as mentioned above.…”

“…The integrated intensity area of the D peak corresponding to the adsorbed hydrogen saturation concentration in the graphene membranes is larger by a factor of about 3 for the area of the D peak, corresponding to the hydrogen concentration in the epitaxial graphene samples. This may be related to some partial hydrogenation localized in some defected nanoregions [33][34][35][36][37][38][39][40][41][42]49] of the epitaxial graphene samples even after the prolonged (3 hour) exposures, i.e. after reaching their near-saturation.…”