Metastable Frenkel pair defect in graphite: source of Wigner energy?

Heggie, M I, Ewels, C P, Telling, R H, El-Barbary, A A and Briddon, P R (2003) Metastable Frenkel pair defect in graphite: source of Wigner energy? Physical Review Letters, 91 (2). 025505. ISSN 0031-9007

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The atomic processes associated with energy storage and release in irradiated graphite have long been subject to untested speculation. We examine structures and recombination routes for interstitial-vacancy (I-V) pairs in graphite. Interaction results in the formation of a new metastable defect (an intimate I-V pair) or a Stone-Wales defect. The intimate I-V pair, although 2.9 eV more stable than its isolated constituents, still has a formation energy of 10.8 eV. The barrier to recombination to perfect graphite is calculated to be 1.3 eV, consistent with the experimental first Wigner energy release peak at 1.38 eV. We expect similar defects to form in carbon nanostructures such as nanotubes, nested fullerenes, and onions under irradiation.

Item Type: Article
Additional Information: MIH directed the work in his group and co-authored the paper. Briddon credited for use of his code (AIMPRO). First explanation of the micro structural changes that store and release energy and identification of the metastable Frenkel pair. Quantitative activation barrier in exact agreement with experiment.
Schools and Departments: School of Life Sciences > Chemistry
Depositing User: Malcolm Heggie
Date Deposited: 06 Feb 2012 20:02
Last Modified: 03 Jul 2019 02:31

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