Direct imaging of a two-dimensional silica glass on graphene |
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Authors: | Huang Pinshane Y Kurasch Simon Srivastava Anchal Skakalova Viera Kotakoski Jani Krasheninnikov Arkady V Hovden Robert Mao Qingyun Meyer Jannik C Smet Jurgen Muller David A Kaiser Ute |
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Affiliation: | School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA. |
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Abstract: | Large-area graphene substrates provide a promising lab bench for synthesizing, manipulating, and characterizing low-dimensional materials, opening the door to high-resolution analyses of novel structures, such as two-dimensional (2D) glasses, that cannot be exfoliated and may not occur naturally. Here, we report the accidental discovery of a 2D silica glass supported on graphene. The 2D nature of this material enables the first atomic resolution transmission electron microscopy of a glass, producing images that strikingly resemble Zachariasen's original 1932 cartoon models of 2D continuous random network glasses. Atomic-resolution electron spectroscopy identifies the glass as SiO(2) formed from a bilayer of (SiO(4))(2-) tetrahedra and without detectable covalent bonding to the graphene. From these images, we directly obtain ring statistics and pair distribution functions that span short-, medium-, and long-range order. Ab initio calculations indicate that van der Waals interactions with graphene energetically stabilizes the 2D structure with respect to bulk SiO(2). These results demonstrate a new class of 2D glasses that can be applied in layered graphene devices and studied at the atomic scale. |
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