title: Defects in bilayer silica and graphene: common trends in diverse hexagonal two-dimensional systems.
abstract: By combining first-principles and classical force field calculations with aberration-corrected high-resolution transmission electron microscopy experiments, we study the morphology and energetics of point and extended defects in hexagonal bilayer silica and make comparison to graphene, another two-dimensional (2D) system with hexagonal symmetry. We show that the motifs of isolated point defects in these 2D structures with otherwise very different properties are similar, and include Stone-Wales-type defects formed by structural unit rotations, flower defects and reconstructed double vacancies. The morphology and energetics of extended defects, such as grain boundaries have much in common as well. As both sp(2)-hybridised carbon and bilayer silica can also form amorphous structures, our results indicate that the morphology of imperfect 2D honeycomb lattices is largely governed by the underlying symmetry of the lattice.
authors: COMP/Department of Applied Physics, Aalto University School of Science, P.O. Box 11100, 00076 Aalto, Finland.
authors: Torbjörn
authors: T
authors: Björkman
authors: Electron Microscopy Group of Materials Science, University of Ulm, Germany 89081.
authors: Simon
authors: S
authors: Kurasch
authors: Electron Microscopy Group of Materials Science, University of Ulm, Germany 89081.
authors: Ossi
authors: O
authors: Lehtinen
authors: 1] Department of Physics, University of Helsinki, P.O. Box 43, 00014 Helsinki, Finland [2] Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1190 Wien, Austria.
authors: Jani
authors: J
authors: Kotakoski
authors: Institute of Theoretical Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors: Oleg V
authors: OV
authors: Yazyev
authors: 1] Max Planck Institute for Solid State Research, Stuttgart, Germany 70569 [2] Department of Physics, Banaras Hindu University, Varanasi, India 221005.
authors: Anchal
authors: A
authors: Srivastava
authors: 1] Max Planck Institute for Solid State Research, Stuttgart, Germany 70569 [2] Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1190 Wien, Austria.
authors: Viera
authors: V
authors: Skakalova
authors: Max Planck Institute for Solid State Research, Stuttgart, Germany 70569.
authors: Jurgen H
authors: JH
authors: Smet
authors: Electron Microscopy Group of Materials Science, University of Ulm, Germany 89081.
authors: Ute
authors: U
authors: Kaiser
authors: 1] COMP/Department of Applied Physics, Aalto University School of Science, P.O. Box 11100, 00076 Aalto, Finland [2] Department of Physics, University of Helsinki, P.O. Box 43, 00014 Helsinki, Finland.
authors: Arkady V
authors: AV
authors: Krasheninnikov