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Vacancy diffusion and coalescence in graphene directed by defect strain fields

Lookup NU author(s): Professor Patrick Briddon, Dr Mark Rayson

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

The formation of extended defects in graphene from the coalescence of individual mobile vacancies can significantly alter its mechanical, electrical and chemical properties. We present the results of ab initio simulations which demonstrate that the strain created by multi-vacancy complexes in graphene determine their overall growth morphology when formed from the coalescence of individual mobile lattice vacancies. Using density functional theory, we map out the potential energy surface for the motion of mono-vacancies in the vicinity of multi-vacancy defects. The inhomogeneous bond strain created by the multi-vacancy complexes strongly biases the activation energy barriers for single vacancy motion over a wide area. Kinetic Monte Carlo simulations based on rates from ab initio derived activation energies are performed to investigate the dynamical evolution of single vacancies in these strain fields. The resultant coalescence processes reveal that the dominant morphology of multi-vacancy complexes will consist of vacancy lines running in the two primary crystallographic directions, and that more thermodynamically stable structures, such as holes, are kinetically inaccessible from mono-vacancy aggregation alone.


Publication metadata

Author(s): Trevethan T, Latham CD, Heggie MI, Briddon PR, Rayson MJ

Publication type: Article

Publication status: Published

Journal: Nanoscale

Year: 2014

Volume: 6

Issue: 5

Pages: 2978-2986

Print publication date: 07/03/2014

Online publication date: 21/01/2014

Acceptance date: 15/01/2014

Date deposited: 07/08/2015

ISSN (print): 2040-3364

ISSN (electronic): 2040-3372

Publisher: RSC Publications

URL: http://dx.doi.org/10.1039/c3nr06222h

DOI: 10.1039/c3nr06222h


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