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Modelling defect evolution in irradiated graphite

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journal contribution
posted on 05.08.2019, 14:17 by Ying Zhou, Kenny Jolley, Rhiannon Phillips, Roger Smith, Houzheng Wu
The diffusion of point defects after irradiation events in graphite is considered using high temperature molecular dynamics and adaptive kinetic Monte Carlo. The system is modelled with a ReaxFF potential model. It is shown that monovacancies can diffuse both within the graphite layers and also between layers to form stable divacancy and trivacancy structures. Interstitials can also combine, first forming interlayer strings which transform to ring structures. Separated ring structures can also combine to form mobile platelets which can be the seed for new layer formation. When a defective lattice contains a local mixture of vacancies and interstitials, both recombination and larger defect clusters can form. The Dienes defect, cannot easily occur by direct transformation as originally proposed, because of high energy barriers but is shown to occur as an intermediate step in interstitial-defect recombination process. At high temperature the graphite layers bend which has the effect of enhancing defect motion and changing the relative stability of monovacancy structures. The consequences of this are discussed.

Funding

EPSRC grant EP/M018822/1, UNIGRAF: Understanding and Improving Graphite for Nuclear Fission

History

School

  • Science

Department

  • Chemistry

Published in

Carbon

Volume

154

Pages

192 - 202

Publisher

Elsevier

Version

AM (Accepted Manuscript)

Publisher statement

This paper was accepted for publication in the journal Carbon and the definitive published version is available at https://doi.org/10.1016/j.carbon.2019.07.092

Acceptance date

27/07/2019

Publication date

2019/08/03

Copyright date

2019

ISSN

0008-6223

Language

en

Depositor

Prof Roger Smith

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