Computer simulation of defect clusters in UO2 and their dependence on composition

Nicholas A. Brincat, M. Molinari, Stephen C. Parker, G. C. Allen, Mark T. Storr

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

It is recognised that point defects play a key role in the behaviour and properties of many technologically significant oxides. What is less well understood is how these defects cluster together and, crucially, the extent to which the clusters change with composition. We chose to investigate this phenomenon by considering UO2, a nuclear fuel material for which there is contradictory data in the literature concerning defect clustering as a function of oxygen content. Early studies of fluorite UO2+x proposed a model based on 2:2:2 Willis clusters whilst more recent research suggests cuboctahedral or split quad-interstitial defect clustering. Here we use the PBE + U functional to simulate defective UO2+x and find for 0.125 < x < 0.25, chains of edge-sharing 2:2:2 Willis clusters to be most stable. Below x = 0.125 these chains destabilise, transforming in to split di-interstitial clusters, demonstrating that the type of oxygen cluster present is dependent on local environment and stoichiometry.

Original languageEnglish
Pages (from-to)329-333
Number of pages5
JournalJournal of Nuclear Materials
Volume456
Early online date13 Oct 2014
DOIs
Publication statusPublished - Jan 2015
Externally publishedYes

Fingerprint

computerized simulation
Defects
defects
Computer simulation
Chemical analysis
Oxygen
Fluorspar
Nuclear fuels
Point defects
Stoichiometry
Oxides
interstitials
nuclear fuels
fluorite
oxygen
point defects
stoichiometry
oxides
Elvitegravir, Cobicistat, Emtricitabine, Tenofovir Disoproxil Fumarate Drug Combination

Cite this

Brincat, Nicholas A. ; Molinari, M. ; Parker, Stephen C. ; Allen, G. C. ; Storr, Mark T. / Computer simulation of defect clusters in UO2 and their dependence on composition. In: Journal of Nuclear Materials. 2015 ; Vol. 456. pp. 329-333.
@article{203ccfb12b4f415b8e3f355a49473da4,
title = "Computer simulation of defect clusters in UO2 and their dependence on composition",
abstract = "It is recognised that point defects play a key role in the behaviour and properties of many technologically significant oxides. What is less well understood is how these defects cluster together and, crucially, the extent to which the clusters change with composition. We chose to investigate this phenomenon by considering UO2, a nuclear fuel material for which there is contradictory data in the literature concerning defect clustering as a function of oxygen content. Early studies of fluorite UO2+x proposed a model based on 2:2:2 Willis clusters whilst more recent research suggests cuboctahedral or split quad-interstitial defect clustering. Here we use the PBE + U functional to simulate defective UO2+x and find for 0.125 < x < 0.25, chains of edge-sharing 2:2:2 Willis clusters to be most stable. Below x = 0.125 these chains destabilise, transforming in to split di-interstitial clusters, demonstrating that the type of oxygen cluster present is dependent on local environment and stoichiometry.",
author = "Brincat, {Nicholas A.} and M. Molinari and Parker, {Stephen C.} and Allen, {G. C.} and Storr, {Mark T.}",
year = "2015",
month = "1",
doi = "10.1016/j.jnucmat.2014.10.001",
language = "English",
volume = "456",
pages = "329--333",
journal = "Journal of Nuclear Materials",
issn = "0022-3115",
publisher = "Elsevier",

}

Computer simulation of defect clusters in UO2 and their dependence on composition. / Brincat, Nicholas A.; Molinari, M.; Parker, Stephen C.; Allen, G. C.; Storr, Mark T.

In: Journal of Nuclear Materials, Vol. 456, 01.2015, p. 329-333.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Computer simulation of defect clusters in UO2 and their dependence on composition

AU - Brincat, Nicholas A.

AU - Molinari, M.

AU - Parker, Stephen C.

AU - Allen, G. C.

AU - Storr, Mark T.

PY - 2015/1

Y1 - 2015/1

N2 - It is recognised that point defects play a key role in the behaviour and properties of many technologically significant oxides. What is less well understood is how these defects cluster together and, crucially, the extent to which the clusters change with composition. We chose to investigate this phenomenon by considering UO2, a nuclear fuel material for which there is contradictory data in the literature concerning defect clustering as a function of oxygen content. Early studies of fluorite UO2+x proposed a model based on 2:2:2 Willis clusters whilst more recent research suggests cuboctahedral or split quad-interstitial defect clustering. Here we use the PBE + U functional to simulate defective UO2+x and find for 0.125 < x < 0.25, chains of edge-sharing 2:2:2 Willis clusters to be most stable. Below x = 0.125 these chains destabilise, transforming in to split di-interstitial clusters, demonstrating that the type of oxygen cluster present is dependent on local environment and stoichiometry.

AB - It is recognised that point defects play a key role in the behaviour and properties of many technologically significant oxides. What is less well understood is how these defects cluster together and, crucially, the extent to which the clusters change with composition. We chose to investigate this phenomenon by considering UO2, a nuclear fuel material for which there is contradictory data in the literature concerning defect clustering as a function of oxygen content. Early studies of fluorite UO2+x proposed a model based on 2:2:2 Willis clusters whilst more recent research suggests cuboctahedral or split quad-interstitial defect clustering. Here we use the PBE + U functional to simulate defective UO2+x and find for 0.125 < x < 0.25, chains of edge-sharing 2:2:2 Willis clusters to be most stable. Below x = 0.125 these chains destabilise, transforming in to split di-interstitial clusters, demonstrating that the type of oxygen cluster present is dependent on local environment and stoichiometry.

UR - http://www.scopus.com/inward/record.url?scp=84908231498&partnerID=8YFLogxK

U2 - 10.1016/j.jnucmat.2014.10.001

DO - 10.1016/j.jnucmat.2014.10.001

M3 - Article

VL - 456

SP - 329

EP - 333

JO - Journal of Nuclear Materials

JF - Journal of Nuclear Materials

SN - 0022-3115

ER -