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Graphene

Notes

From 03/24/2015 through 2/7/2012

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Notes

“Graphite may be formed of a stacked structure of two-dimensional planar sheets in which carbon atoms may be bonded in an extended fused array of hexagonal rings. A single sheet of the extended fused array of six-membered carbon rings may be referred to as graphene.

Graphene sheet, as defined herein, may comprise one or more sheets of graphene. Graphene sheet may have advantageous properties different from those of other materials. In particular, electrons may move on the graphene sheet as if they have zero mass, which means that the electrons may move at the velocity at which light moves in vacuum. Electron mobility on graphene sheet has been found to be about 20,000 to 50,000 cm.sup.2/Vs. Further, graphene sheet may exhibit unusual half-integer quantum hall effects for electrons and holes.

Since the electrical properties of graphene sheet with a given thickness may be changed depending on its crystal orientation, the electrical properties may be controlled by selecting the crystalline orientation of the graphene sheet and to this end, designing devices with different electrical properties using graphene sheet may be relatively straightforward. The electrical properties of graphene sheet may be compared with those of a carbon nanotube ("CNT"), which is known to exhibit metallic or semiconducting properties dependent upon the chirality and diameter of the CNT. A complicated separation process may be required in order to take advantage of such metallic or semiconducting properties of CNTs. Graphene sheet may also have economic advantages over CNTs in that because no purification may be needed, as with synthesized CNTs, graphene sheets may be less expensive. Therefore, graphene sheet may be widely used for carbon-based electrical or electronic devices.

Graphene sheets may be prepared generally by a micromechanical process or by a SiC crystal pyrolysis process.

A micromechanical process may be a method that may include, for example, attaching a tape onto a surface of a graphite sample, and releasing the tape from the surface by peeling, to obtain a graphene sheet adhered to the tape coming off the graphite. The tape may be then released from the graphene sheet by, for example, dissolving the tape in a solvent.

The SiC crystal pyrolysis process may be a method that may include, for example, heating a SiC single crystal to decompose SiC on the surface of the crystal. The Si may be removed after the decomposition, and the remaining carbon (C) may form the graphene sheet.”

[Shen, Choi and Yoon, US Patent 8,133,466 (3/13/2012)]

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Roger D. Corneliussen
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www.maropolymeronline.com

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Copyright 2012 by Roger D. Corneliussen.
No part of this transmission is to be duplicated in any manner or forwarded by electronic mail without the express written permission of Roger D. Corneliussen
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* Date of latest addition; date of first entry is 5/1/2012.

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