title: Dynamical observations on the crack tip zone and stress corrosion of two-dimensional MoS2.
abstract: Whether and how fracture mechanics needs to be modified for small length scales and in systems of reduced dimensionality remains an open debate. Here, employing in situ transmission electron microscopy, atomic structures and dislocation dynamics in the crack tip zone of a propagating crack in two-dimensional (2D) monolayer MoS2membrane are observed, and atom-to-atom displacement mapping is obtained. The electron beam is used to initiate the crack; during in situ observation of crack propagation the electron beam effect is minimized. The observed high-frequency emission of dislocations is beyond previous understanding of the fracture of brittle MoS2. Strain analysis reveals dislocation emission to be closely associated with the crack propagation path in nanoscale. The critical crack tip plastic zone size of nearly perfect 2D MoS2is between 2 and 5 nm, although it can grow to 10 nm under corrosive conditions such as ultraviolet light exposure, showing enhanced dislocation activity via defect generation.
authors.affiliation: IBS Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: Thuc Hue
authors.initials: TH
authors.lastname: Ly
authors.affiliation: IBS Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: Jiong
authors.identifier: 0000-0002-7411-0734
authors.initials: J
authors.lastname: Zhao
authors.affiliation: IBS Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science, Sungkyunkwan University, Suwon 440-746, Korea.|Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: Magdalena Ola
authors.initials: MO
authors.lastname: Cichocka
authors.affiliation: Physical Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.
authors.forename: Lain-Jong
authors.identifier: 0000-0002-4059-7783
authors.initials: LJ
authors.lastname: Li
authors.affiliation: IBS Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science, Sungkyunkwan University, Suwon 440-746, Korea.|Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: Young Hee
authors.identifier: 0000-0001-7403-8157
authors.initials: YH
authors.lastname: Lee