Effective Defects: Strength in Numbers. The surprising strength of highly defective graphene

Graphene in its pristine form is one of the strongest materials, but defects influence its strenth.  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.