Atomistic dynamics of sulfur-deficient high-symmetry grain boundaries in molybdenum disulfide

JH Hong and YL Wang and AL Wang and DH Lv and CH Jin and ZP Xu and MIJ Probert and J Yuan and Z Zhang, NANOSCALE, 9, 10312-10320 (2017).

DOI: 10.1039/c7nr02941a

As a common type of structural defect, grain boundaries (GBs) play an important role in tailoring the physical and chemical properties of bulk crystals and their two-dimensional (2D) counterparts such as graphene and molybdenum disulfide (MoS2). In this study, we explore the atomic structures and dynamics of three kinds of high-symmetry GBs (alpha, beta and gamma) in monolayer MoS2. Atomic-resolution transmission electron microscopy (TEM) is used to characterize their formation and evolutionary dynamics, and atomistic simulation based analysis explains the size distribution of alpha-type GBs observed under TEM and the inter-GB interaction, revealing the stabilization mechanism of GBs by pre-existing sulfur vacancies. The results elucidate the correlation between the observed GB dynamics and the migration of sulfur atoms across GBs via a vacancy-mediated mechanism, offering a new perspective for GB engineering in monolayer MoS2, which may be generalized to other transition metal dichalcogenides.

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