Fragmentation and structural transitions of few-layer graphene under high shear stress

Abstract

A key factor that determines the mechanical and electrical performance of graphene-based materials and devices is how graphene behaves under extreme conditions, yet the response of few-layer graphene to high shear stress has not been investigated experimentally. Here we applied high pressure and shear to graphene powder using a rotational diamond anvil cell and studied the recovered sample with multiple means of characterization. Sustaining high pressure and shear, graphene breaks into nanometer-long clusters with generation of large number of defects. At a certain stress level, it transforms to amorphous state and carbon onions. The reduction of infrared reflectivity in the severely sheared phase indicates the decrease in conductivity. Our results unveil the shear sensitive nature of graphene, point out the effects of shear on its physical properties, and provide a potential method to manipulate this promising material.

The shear strain energy fluctuations caused by random porosities in graphene based on the stochastic finite element model

“…In figure 5, the probability density distributions of porous graphene samples are presented. For P 1 , P 2 and P 3 , the histograms of S, D 2 , and Q are clustered closely. Furthermore, probability density distributions of Q in figure 5(c) are closer to the Gaussian distribution compared with that in figures 5(a) and (b).…”

“…(2.6) present S, D 2 , and Q, respectively. P 1 , P 2 , P 3 , P 4 , and P 5 represent 0.1%, 0.5%, 1%, 3%, and 5%, respectively).…”

“…In order to analyze the fluctuations and variations of the strain energy caused by the random atomic vacancy defects, the finite element computation is performed in all the stochastic samples of porous graphene. For each stochastic sample, the corresponding S and D 2 are feasible to be computed and tracked, and S and D 2 stochastic samples for porous graphene. The results of pristine graphene are recorded as S 0 and D 2 0 for further comparison.…”

“…Shear strain was found to cause the formation of wrinkles and frictions in the multilayers of graphene [1]. Shear stress in graphene is influential, which leads to the reduction of infrared reflectivity, transformation into amorphous state and carbon onions, generation of a larger number of defects, fracture into nanometer clusters and fragmentations [2]. The shear modulus, fracture strength and related strain of both zigzag and armchair graphene vary according to different temperatures [3].…”

Micromechanical Landscape of Three-Dimensional Disordered Graphene Networks

“…Figure g highlights new sp 3 bonds (shown in green) and sp-free edges (shown in red) during compression and shear. Recent experiments and simulations demonstrated that sp 3 -carbon nanoforms transformed from graphene under extreme compression or shear, ,, which should be relative to the rebonding mechanism of sp 3 atoms originating from local damaged fragments. Although nonlinear deformation and local damage appear in graphene networks, the whole structure can still sustain an anomalously large strain before failure …”