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Materials

A Glimpse Of Glass On Graphene

Images of two-dimensional silica glass confirm 80-year-old theoretical model

by Bethany Halford
February 13, 2012 | APPEARED IN VOLUME 90, ISSUE 7

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Credit: Nano Lett.
Zachariasen’s 1932 model of amorphous silica (top) and the real thing (bottom) as seen with a scanning transmission electron microscope.
09007-scicon-silicaFib1cxd.jpg
Credit: Nano Lett.
Zachariasen’s 1932 model of amorphous silica (top) and the real thing (bottom) as seen with a scanning transmission electron microscope.

The thinnest possible layer of silica glass has been prepared on a graphene surface, giving scientists the first opportunity to directly observe the atomic arrangement of this amorphous material (Nano Lett., DOI: 10.1021/nl204423x). Researchers led by David A. Muller of Cornell University and Ute Kaiser of the University of Ulm, in Germany, were trying to grow graphene on copper foil when an air leak in their chemical vapor deposition apparatus caused the copper to react with a glass tube, leaving a two-dimensional silica layer attached to the graphene. With a 2-D layer of silica in hand, Muller and Kaiser realized they could, for the first time, study the glass with atomic-resolution transmission electron microscopy. The striking images they obtained match models proposed in 1932 by University of Chicago physicist W. H. Zachariasen. The amorphous structures have variable bond angles between SiO2 molecules, introducing structural disorder in which there are continuous networks of rings of different sizes. Muller and Kaiser suggest the new class of 2-D glasses could find use in semiconductors or layered-graphene electronics.

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