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Title: Diffusion of oxygen in uranium dioxide: A first-principles investigation

Abstract

Results of ab initio density-functional theory calculations of the migration energies of oxygen vacancies and interstitials in stoichiometric UO{sub 2} are reported. The diffusion of oxygen vacancies in UO{sub 2} is found to be highly anisotropic, and the [1 0 0] direction is energetically favored. The atomic relaxations play an important role in reducing the migration barriers. Within the generalized gradient approximation (GGA), we find that the migration energies of the preferred vacancies and interstitials paths are, respectively, 1.18 and 1.09 eV. With the inclusion of the Hubbard U parameter to account for the 5f electron correlations in GGA+U, the vacancy migration energy is lowered to 1.01 eV while the interstitial migration energy increases slightly to 1.13 eV. We find, however, that the correlation effects have a drastic influence on the mechanism of interstitial migration through the stabilization of Willis-type clusters. Indeed, in contrast to GGA, in GGA+U there is an inversion of the migration path with the so-called 'saddle-point' position being lower in energy than the usual starting position. Thus while the migration barriers are nearly the same in GGA and GGA+U, the mechanisms are completely different. Our results clearly indicate that both vacancies and interstitials contribute almost equallymore » to the diffusion of oxygen in UO{sub 2}.« less

Authors:
;  [1];  [2]
  1. IRSN, DPAM, SEMIC, LETR, Saint Paul Lez Durance (France)
  2. Laboratoire de Physique et Modelisation des Milieux Condenses, CNRS, Maison des Magisteres, 25 Avenue des Martyrs, BP 166, 38042 Grenoble (France)
Publication Date:
OSTI Identifier:
21366645
Resource Type:
Journal Article
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 81; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevB.81.014110; (c) 2010 The American Physical Society; Journal ID: ISSN 1098-0121
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANISOTROPY; APPROXIMATIONS; DENSITY FUNCTIONAL METHOD; DIFFUSION; ELECTRON CORRELATION; INCLUSIONS; INTERSTITIALS; MIGRATION; OXYGEN; RELAXATION; SIMULATION; STABILIZATION; STOICHIOMETRY; URANIUM DIOXIDE; VACANCIES; ACTINIDE COMPOUNDS; CALCULATION METHODS; CHALCOGENIDES; CORRELATIONS; CRYSTAL DEFECTS; CRYSTAL STRUCTURE; ELEMENTS; NONMETALS; OXIDES; OXYGEN COMPOUNDS; POINT DEFECTS; URANIUM COMPOUNDS; URANIUM OXIDES; VARIATIONAL METHODS

Citation Formats

Gupta, Florence, Brillant, Guillaume, and Pasturel, Alain. Diffusion of oxygen in uranium dioxide: A first-principles investigation. United States: N. p., 2010. Web. doi:10.1103/PHYSREVB.81.014110.
Gupta, Florence, Brillant, Guillaume, & Pasturel, Alain. Diffusion of oxygen in uranium dioxide: A first-principles investigation. United States. doi:10.1103/PHYSREVB.81.014110.
Gupta, Florence, Brillant, Guillaume, and Pasturel, Alain. Fri . "Diffusion of oxygen in uranium dioxide: A first-principles investigation". United States. doi:10.1103/PHYSREVB.81.014110.
@article{osti_21366645,
title = {Diffusion of oxygen in uranium dioxide: A first-principles investigation},
author = {Gupta, Florence and Brillant, Guillaume and Pasturel, Alain},
abstractNote = {Results of ab initio density-functional theory calculations of the migration energies of oxygen vacancies and interstitials in stoichiometric UO{sub 2} are reported. The diffusion of oxygen vacancies in UO{sub 2} is found to be highly anisotropic, and the [1 0 0] direction is energetically favored. The atomic relaxations play an important role in reducing the migration barriers. Within the generalized gradient approximation (GGA), we find that the migration energies of the preferred vacancies and interstitials paths are, respectively, 1.18 and 1.09 eV. With the inclusion of the Hubbard U parameter to account for the 5f electron correlations in GGA+U, the vacancy migration energy is lowered to 1.01 eV while the interstitial migration energy increases slightly to 1.13 eV. We find, however, that the correlation effects have a drastic influence on the mechanism of interstitial migration through the stabilization of Willis-type clusters. Indeed, in contrast to GGA, in GGA+U there is an inversion of the migration path with the so-called 'saddle-point' position being lower in energy than the usual starting position. Thus while the migration barriers are nearly the same in GGA and GGA+U, the mechanisms are completely different. Our results clearly indicate that both vacancies and interstitials contribute almost equally to the diffusion of oxygen in UO{sub 2}.},
doi = {10.1103/PHYSREVB.81.014110},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
issn = {1098-0121},
number = 1,
volume = 81,
place = {United States},
year = {2010},
month = {1}
}