Intrinsic mechanical properties and fracture mechanism of monolayer penta-graphene investigated by nanoindentation: A molecular dynamics study

[Display omitted] •MD simulation of indentation is carried out on monolayer penta-graphene.•Intrinsic mechanical properties of penta-graphene are determined.•Fracture mechanism of penta-graphene under contact condition has been investigated. A new carbon allotrope called penta-graphene (PG) consisting of sp2 and sp3 hybridization has been confirmed to be dynamically, thermally and mechanically stable via ab initio calculations. In this work, we resort to the MD simulation to investigate the intrinsic mechanical properties and fracture mechanism of PG as well as graphene (GP) with only sp2 during indentation. It is turned out that the PG film exhibits higher ductility than the GP as it has higher resistance force and larger critical fracture depth. The comparison of atomic configurations for the GP and the PG also proves that the PG film possesses a better capability to deform and withstand the damage since it has smaller cracks under the same loading condition. Furthermore, we probe into the fracture mechanism at the initial fracture point and reveal the fact that the crack is nucleated with the breakage of sp3 bonds, and the broken bonds can recombine to form new sp3 bonds which contributes to its high resistance to external force even after the crack. In addition, the typical force-displacement relationship is also obtained, from which its elastic modulus and breaking strength are determined as 579.46 GPa and 60.90 GPa, respectively.