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Chris Ewels: Escape from Graphene Flatland

posted 11 Jul 2011, 01:34 by Peter Bøggild
In 2004 Graphene was considered an infinite flat two dimensional sheet. In 2007 it was shown that it flaps and waves like a flag in the wind. As we continue to learn more about this fascinating material, we increasingly realise that the world of graphene is anything but flat.

Conventional three-dimensional crystal lattices are terminated by surfaces, which can demonstrate complex rebonding and rehybridisation, localised strain and dislocation formation. Two dimensional crystal lattices, of which graphene is the archetype, are terminated by lines. The additional available dimension at such interfaces opens up a range of new topological interface possibilities. We show that graphene sheet edges can adopt a range of topological distortions depending on their nature. Rehybridisation, local bond reordering, chemical functionalisation with bulky, charged, or multi-functional groups can lead to edge buckling to relieve strain [1], folding, rolling [2] and even tube formation [3]. We discuss the topological possibilities at a 2D graphene edge, and under what circumstances we expect different edge topologies to occur. Density functional calculations are used to explore in more depth different graphene edge types. Finally we examine the effect of this on graphene properties, and lay out some of the challenges graphene designers face if it is to live up to its promise as the defining material of the 21st century.

Authors: Chris Ewels1, V. Ivanovskaya1, Ph. Wagner1, A. Yaya1, A. Zobelli2, M. Heggie3, P. Briddon4, 1 : Institute of Materials, CNRS, University of Nantes, France, 2: LPS, Universite Paris Sud, Orsay, Franc, 3 : Chemistry Department, University of Sussex, Brighton, UK, 4 : University of Newcastle Upon Tyne, UK

[1] Ph. Wagner, C. Ewels, V. V. Ivanovskaya, P. R. Briddon, A. Pateau, B. Humbert, submitted (2011)
[2] V. V. Ivanovskaya, Ph. Wagner, A. Zobelli, I. Suarez-Martinez, A. Yaya, C. P. Ewels, submitted (Proc. GraphITA 2011, Wiley, 2011)
[3] V. V. Ivanovskaya, A. Zobelli, Ph. Wagner, M. Heggie, P. R. Briddon, M. J. Rayson, C. P. Ewels, Phys. Rev. Lett. In press (2011).

Chris Ewels graduated from Oxford University in 1993 after studying “Metallurgy and the Science of Materials”. He received a Ph.D. in 1997 from the University of Exeter UK, for computational studies of oxygen defects in silicon. He then moved to Sussex University where he worked on modelling radiation induced defects in nuclear graphite and carbon nanosystems. At Sussex he joined the Vega Science Trust with Sir Harry Kroto, where he created an online science TV channel and developed a passion for public communication of science. In Paris he worked at ONERA and was then a Marie Curie Individual Research Fellow at the Universite Paris Sud within the electron microscopy group of Professor Christian Colliex. In 2006 he took up a permanent post with the CNRS at the Institute of Materials in Nantes. His work focuses on computer modelling of point and line defects in nanoscale carbons, and he has authored over 90 journal publications including six book chapters. His interest in science communication continues, exhibiting his nanoscience images in the US (www.ewels.info) and producing YouTube videos for the EU project nano2hybrids (www.nano2hybrids.net). He writes regularly for national and international newspapers and websites. In 2006 he received the European Marie Curie Excellence Award.