Graphene/hexagonal boron nitride heterostructures: Mechanical properties and fracture behavior from nanoindentation simulations
G Mallick and RM Elder, APPLIED PHYSICS LETTERS, 113, 121902 (2018).
In-plane or vertically stacked heterostructures containing multiple 2D materials are promising for emerging applications, such as flexible electronics, piezoelectric sensors, and molecular separations. However, utilizing heterostructures requires a fundamental understanding of their mechanics, which is currently lacking. Here, we use reactive molecular dynamics to simulate nanoindentation of stacked hexagonal boron nitride (h-BN) and graphene structures, 2D materials with similar structures but differing electronic properties. We calculate the Young's modulus, bending rigidity, ultimate strength, and the fracture strain of monolayers, homogeneous and heterogeneous bilayers, and alternating trilayers. Their mechanics are broadly similar, although graphene provides mild reinforcement to heterostructures. Further, we characterize the puncture created by nanoindentation. where we find that graphene allows smaller pores with a rougher fracture surface and more cleaved bonds than h-BN, which we attribute to differences in toughness. Our results demonstrate that these layered heterostructures maintain their mechanical robustness regardless of stacking order and provide insight into the influence of layer ordering in separation or passivation applications.
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