title: Dislocation motion and grain boundary migration in two-dimensional tungsten disulphide.
abstract: Dislocations have a significant effect on mechanical, electronic, magnetic and optical properties of crystals. For a dislocation to migrate in bulk crystals, collective and simultaneous movement of several atoms is needed. In two-dimensional crystals, in contrast, dislocations occur on the surface and can exhibit unique migration dynamics. Dislocation migration has recently been studied in graphene, but no studies have been reported on dislocation dynamics for two-dimensional transition metal dichalcogenides with unique metal-ligand bonding and a three-atom thickness. This study presents dislocation motion, glide and climb, leading to grain boundary migration in a tungsten disulphide monolayer. Direct atomic-scale imaging coupled with atomistic simulations reveals a strikingly low-energy barrier for glide, leading to significant grain boundary reconstruction in tungsten disulphide. The observed dynamics are unique and different from those reported for graphene. Through strain field mapping, we also demonstrate how dislocations introduce considerable strain along the grain boundaries and at the dislocation cores.
authors.affiliation: 1] Department of Materials Science and Engineering, Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA [2] Center for Two Dimensional and Layered Materials, Pennsylvania State University, University Park, Pennsylvania 16802, USA [3].
authors.forename: Amin
authors.initials: A
authors.lastname: Azizi
authors.affiliation: 1] Department of Materials Science and Nano-Engineering, and the Richard Smalley Institute, Rice University, Houston, Texas 77005, USA [2].
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Zou
authors.affiliation: National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Ercius
authors.affiliation: Department of Materials Science and Nano-Engineering, and the Richard Smalley Institute, Rice University, Houston, Texas 77005, USA.
authors.forename: Zhuhua
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: 1] Center for Two Dimensional and Layered Materials, Pennsylvania State University, University Park, Pennsylvania 16802, USA [2] Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Ana Laura
authors.initials: AL
authors.lastname: Elías
authors.affiliation: 1] Center for Two Dimensional and Layered Materials, Pennsylvania State University, University Park, Pennsylvania 16802, USA [2] Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Néstor
authors.initials: N
authors.lastname: Perea-López
authors.affiliation: Department of Materials Science and Engineering, Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Greg
authors.initials: G
authors.lastname: Stone
authors.affiliation: 1] Department of Materials Science and Engineering, Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA [2] Center for Two Dimensional and Layered Materials, Pennsylvania State University, University Park, Pennsylvania 16802, USA [3] Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA [4] Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Terrones
authors.affiliation: Department of Materials Science and Nano-Engineering, and the Richard Smalley Institute, Rice University, Houston, Texas 77005, USA.
authors.forename: Boris I
authors.initials: BI
authors.lastname: Yakobson
authors.affiliation: 1] Department of Materials Science and Engineering, Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA [2] Center for Two Dimensional and Layered Materials, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Nasim
authors.initials: N
authors.lastname: Alem