Self healing nature of bilayer graphene

• Strength of bilayer graphene sheet is independent of the loading direction.
• The zigzag stacked AA bilayer sheet has 1.15 times higher fracture strength as compared to the armchair stacked AA bilayer graphene sheet.
• Self healing occurred for critical crack opening distance less than 5 Å for AA stacked sheet and 13 Å for AB stacked bilayer graphene sheet.
• Self healing was observed for both AB and AA stacking of bilayer graphene sheet.
• The healed sheets of bilayer graphene contained defects which resulted in 20% decrease in its ultimate tensile strength.

The phenomenon of self healing of cracks in bilayer graphene sheet has been studied using molecular dynamics simulations. The bilayer graphene sheet was subjected to uniaxial tensile load resulting in initiation and propagation of cracks on exceeding the ultimate tensile strength. Subsequently, all forces acting on the sheet were removed and sheet was relaxed. The cracks formed in the graphene sheet healed without any external aid within 0.4 ps The phenomenon of self healing of the cracks in graphene sheet was found to be independent of the length of the crack, but occurred for critical crack opening distance less than 5 Å for AA stacked sheet and 13 Å for AB stacked bilayer graphene sheet. Self healing was observed for both AB (mixed stacking of armchair and zigzag graphene sheet) and AA (both sheets of similar orientation i.e. either armchair-armchair or zigzag-zigzag) stacking of bilayer graphene sheet.

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