Atomistic study on the strength of symmetric tilt grain boundaries in graphene

Molecular dynamics (MD) simulations were employed to study the mechanical response of various bicrystal graphene consisting of symmetric tilt boundary subject to uniaxial tensile loading at room temperature. We found that the strength of zigzag-oriented graphene increases slightly with mis-orientation angle, while the strength of armchair-oriented graphene deceases slightly with mis-orientation angle. Given that the difference in strength is small, one might conclude that the dependence of strength of graphene sheet containing grain boundaries upon tilt mis-orientation angle is rather weak. The origin for such weak dependence is believed to be that these grain boundaries all consisting of pentagon-heptagon pairs do not resemble nano-cracks, which result in rather heterogeneous stress field around the crack tip and therefore stress gradient plays an important role. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4722786]