Direct Imaging of a Two-Dimensional Silica Glass on Graphene
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- 作者：Pinshane Y. Huang ; Simon Kurasch ; Anchal Srivastava ; Viera Skakalova ; Jani Kotakoski ; Arkady V. Krasheninnikov ; Robert Hovden ; Qingyun Mao ; Jannik C. Meyer ; Jurgen Smet ; David A. Muller ; Ute Kaiser
- 刊名：Nano Letters
- 出版年：2012
- 出版时间：February 8, 2012
- 年：2012
- 卷：12
- 期：2
- 页码：1081-1086
- 全文大小：460K
- 年卷期：v.12,no.2(February 8, 2012)
- ISSN：1530-6992
文摘
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鈥檚 original 1932 cartoon models of 2D continuous random network glasses. Atomic-resolution electron spectroscopy identifies the glass as SiO2 formed from a bilayer of (SiO4)2鈥?/sup> 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 SiO2. These results demonstrate a new class of 2D glasses that can be applied in layered graphene devices and studied at the atomic scale.