A coarse-grained simulation for tensile behavior of 2D Au nanocrystal superlattices
XP Liu and Y Ni and LH He, NANOTECHNOLOGY, 25, 475704 (2014).
We performed a coarse-grained. molecular dynamics (MD) simulation to study the unidirectional tension of 2D superlattices of alkythiol- ligated Au nanocrystals (NCs). Consistent with available experiments, the predicted Young's modulus is in the range of 6-15 GPa, exhibiting a trend of decreasing with the increasing NCs' size and decreasing ligand length. Our simulation shows that the deformation of the superlattice experiences elastic and nonelastic stages before defect nucleation at the NC level. The larger tensile strain gives rise to slips along the most densely packed lines, making them equal to +/- 60 degrees with the tensile direction before deformation, which further triggers the occurrence of cavities and cracks and finally leads to the fracture of the specimen. These results provide a clear picture for the tensile behavior of 2D superlattices from deformation to rupture.
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