Role of structural symmetry breaking in the structurally induced robust superlubricity of graphene and h-BN homo- and heterojunctions

摘要

The registry index (RI) model has been used to investigate the sliding energy corrugation between pristine graphene (G), h-BN, graphene-585-extended line defect (GD) and h-BN-585-extended line defect (BND) bilayer systems. Two homo (G(D)@G, BND@BN) and two hetero (G(D)@BN, and BND@G) junctions were investigated and the results compared to their defect free counterparts. The analysis of RI corrugation reveals that robust superlubricity appears in the defective G(D)@G and BND@BN homo-junctions. This is interpreted as a result of symmetry breaking of the sliding flake and is in contrast to the case of defect free G@G and BN@BN homo-junctions where flake reorientations remove superlubricity. The 585 extended line defect (585-ELD) in the sliding flakes acts as structural anisotropy enhancers in the G(D)@BN and BND@G hetero-junctions and it can be regarded as the origin of the predicted robust superlubricity. The present theoretical models suggest that embedded 585-ELD topological defect on both homogeneous and heterogeneous junctions results in promising candidates for dry lubrication purposes. (C) 2015 Elsevier Ltd. All rights reserved.