Atomic diffusion mechanism of Xe in UO2

Yun, Young-ju; Kim, Hanchul; Kim, Heemoon; Park, Kwangheon

doi:10.1016/j.jnucmat.2008.04.013

Cited by 75 publications

(37 citation statements)

References 35 publications

(39 reference statements)

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“…Therefore, it is likely that SDs are too small to be solely responsible for xenon diffusion. 7,8,9 The number of vacancies required for xenon diffusion or the mechanism by which the xenonvacancy complex diffuse is not known experimentally. Because of the difficulty of measuring atomic scale properties, calculating these properties in UO 2 has been of interest using both Density Functional Theory (DFT) 7,10,11,12,13,14,15,16,17,18,19 as well as empirical potentials.…”

Section: Introductionmentioning

confidence: 99%

“…7,8,9 The number of vacancies required for xenon diffusion or the mechanism by which the xenonvacancy complex diffuse is not known experimentally. Because of the difficulty of measuring atomic scale properties, calculating these properties in UO 2 has been of interest using both Density Functional Theory (DFT) 7,10,11,12,13,14,15,16,17,18,19 as well as empirical potentials. 8,9,11,12,19,20,21,22,23 Several theoretical investigations of xenon in UO 2 have studied diffusion via a tetravacancy (TV, 2 V U + 2 V O ) mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…8,9,11,12,19,20,21,22,23 Several theoretical investigations of xenon in UO 2 have studied diffusion via a tetravacancy (TV, 2 V U + 2 V O ) mechanism. 7,8,9 These previous investigations have proposed a variety of diffusion pathways for xenon using empirical potentials, Nudged Elastic Band (NEB), and constrained relaxations. While overall xenon transport in UO 2 has a large activation energy, that barrier can be attributed to uranium vacancy migration within the defect cluster rather than xenon migration.…”

Section: Introductionmentioning

confidence: 99%

“…Grimes et al 9 showed that xenon migration within a TV (XeTV) has a lower barrier than uranium migration, and therefore, uranium migration is the limiting factor for xenon transport. Yun et al 7 proposed that xenon would be immobile in a Schottky defect until a (second) uranium vacancy approached the xenon-Schottky defect cluster. The xenon atom could move from the first uranium vacancy to the second, leaving the first uranium vacancy to dissociate from the SD.…”

Section: Introductionmentioning

confidence: 99%

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Pathway and energetics of xenon migration in uranium dioxide

Thompson

Wolverton

2013

Phys. Rev. B

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Using a combination of Density Functional Theory (DFT), classical potentials, Molecular Dynamics (MD), and Nudged Elastic Band (NEB) calculations, we explore the diffusion of xenon in uranium dioxide (UO 2 ). We compare migration barriers of empirical potentials with DFT by performing NEB calculations and subsequently we use the DFT-validated empirical potentials to calculate vacancy clusters, with and without xenon, to determine the migration path and barrier of xenon in bulk UO 2 . We find (i) two empirical potentials out of four tested agree qualitatively with DFT derived energetics for Schottky defect migration, (ii) through the use of molecular dynamics with empirical potentials, we have found a new path for the diffusion of xenon-tetravacancy clusters (Xe + 2 V U + 2 V O ), (iii) this new path has an energy barrier significantly lower than previously reported paths by nearly 1 eV, (iv) we examine the physical contributions to the migration pathway and find the barrier is largely electrostatic and that xenon contributes very little to the barrier height, (v) once a uranium vacancy attaches to a xenonSchottky defect, the resulting xenon-tetravacancy cluster is strongly bound, and (vi) like xenon in a tetravacancy, a xenon-double Schottky defect can diffuse in a concerted manor with a comparable barrier to xenon in a tetravacancy, but two of the oxygen vacancies are only weakly bound to the defect.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pathway and energetics of xenon migration in uranium dioxide

Thompson

Wolverton

2013

Phys. Rev. B

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“…The data points and associated error bars reflect the means and standard deviations of the measurements. The measurements were all 32 oxygen vacancy diffusivity as the mechanism of charge transfer inside this material is believed to be via an oxygen vacancy mechanism [24]. As a result, the curve of dc conductivity versus dopant concentration in [23] reflects oxygen vacancy self-diffusivity change with La dopant concentration within the CeO2 lattice.…”

Section: Xenon Precipitation In Ceomentioning

confidence: 99%