Anomalous Strength Characteristics of Tilt Grain Boundaries in Graphene

By Rassin Grantab, V. Shenoy, Rodney S. Ruoff. Science, 2010

801 citations recorded by the source corpus.

Perfect Imperfections Graphene is composed of six-atom rings, but will include a number of five- and seven-atom rings as defects. Using simulations, Grantab et al. (p. 946) show that more defects do not necessarily lead to greater deterioration of mechanical properties. Mismatches caused by differences in the orientation of neighboring crystals are divided into low- and high-angle grain boundaries, and typically it is the lower-angle boundaries that are stronger. In graphene, by contrast, the larger-angle boundaries, which consist of higher-defect densities, are better able to accommodate the strain and prevent failure that originates in the breakup of the seven-member graphene rings. This suggests ways for synthesizing imperfect graphene sheets that will have mechanical properties that are close to those of perfect graphene. Simulations indicate that high-angle boundaries can better accommodate strain and prevent failure in graphene. Graphene in its pristine form is one of the strongest materials tested, but defects influence its strength. Using atomistic calculations, we find that, counter to standard reasoning, graphene sheets with large-angle tilt boundaries that have a high density of defects are as strong as the pristine material and, unexpectedly, are much stronger than those with low-angle boundaries having fewer defects. We show that this trend is not explained by continuum fracture models but can be understood by considering the critical bonds in the strained seven-membered carbon rings that lead to failure; the large-angle boundaries are stronger because they are able to better accommodate these strained rings. Our results provide guidelines for designing growth methods to obtain sheets with strengths close to that of pristine graphene.

Subfields: Computational Mechanics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/18a2f2c342e754c815dc2836f3a084ffc96c225d

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Citations in the corpus

A review on mechanics and mechanical properties of 2D materials—Graphene and beyond (2016, background): “For example, the strength of a bi-crystal graphene is highly dependent on the grain boundary [107,108,131], which was recently explained with a disclination dipole theory [108].”
Atomistic simulation and continuum modeling of graphene nanoribbons under uniaxial tension (2011, background): “Grantab et al [51] have demonstrated by atomistic calculations an anomalous effect of tilt grain boundaries on the strength of graphene.”
Tailoring the mechanical properties of 2D materials and heterostructures (2018, background): “In Grantab et al [74] the MD simulations show that the fracture strength increases with the increase in the tilt angle and therefore with the increase of the defect density.”
High strength measurement of monolayer graphene oxide (2015, background): “Additionally, the presence of even a small number of defects is known to promote premature failure in 2D systems which may further limit the measureable experimental strength of monolayer GO [37,38].”
Carbon nanotube- and graphene-reinforced multiphase polymeric composites: review on their properties and applications (2019, background): “The addition of 11 wt% GNS enhanced Young’s modulus from 2.01 to 4.04 GPa, whereas the maximum tensile strength and elongation achieved were 98.5 MPa and 28.9% with the incorporation of 0.5 wt% and 0.1 wt% GNS, respectively.”
Production and processing of graphene and related materials (2020, background): “Also, the presence of grain boundaries and their tilting has been studied in relation to the mechanical properties of the synthesized graphene [811].”