title: Temperature dependence of the reconstruction of zigzag edges in graphene.
abstract: We examine the temperature dependence of graphene edge terminations at the atomic scale using an in situ heating holder within an aberration-corrected transmission electron microscope. The relative ratios of armchair, zigzag, and reconstructed zigzag edges from over 350 frames at each temperature are measured. Below 400 °C, the edges are dominated by zigzag terminations, but above 600 °C, this changes dramatically, with edges dominated by armchair and reconstructed zigzag edges. We show that at low temperature chemical etching effects dominate and cause deviation to the thermodynamics of the system. At high temperatures (600 and 800 °C), adsorbates are evaporated from the surface of graphene and chemical etching effects are significantly reduced, enabling the thermodynamic distribution of edge types to be observed. The growth rate of holes at high temperature is also shown to be slower than at room temperature, indicative of the reduced chemical etching process. These results provide important insights into the role of chemical etching effects in the hole formation, edge sputtering, and edge reconstruction in graphene.
authors.affiliation: †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K.
authors.forename: Kuang
authors.initials: K
authors.lastname: He
authors.affiliation: †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K.
authors.forename: Alex W
authors.initials: AW
authors.lastname: Robertson
authors.affiliation: †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K.
authors.forename: Ye
authors.initials: Y
authors.lastname: Fan
authors.affiliation: †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Allen
authors.affiliation: ‡Nanotube Research Center, Advanced Institute for Industrial Science and Technology, Tsukuba 305-8561, Japan.
authors.forename: Yung-Chang
authors.initials: YC
authors.lastname: Lin
authors.affiliation: ‡Nanotube Research Center, Advanced Institute for Industrial Science and Technology, Tsukuba 305-8561, Japan.
authors.forename: Kazu
authors.initials: K
authors.lastname: Suenaga
authors.affiliation: †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K.
authors.forename: Angus I
authors.initials: AI
authors.lastname: Kirkland
authors.affiliation: †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K.
authors.forename: Jamie H
authors.initials: JH
authors.lastname: Warner
keywords: HRTEM; edges; graphene; high temperature; reconstructed zigzag