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Title: First-principles study of noble gas impurities and defects in UO{sub 2}

Abstract

We performed a series of density functional theory + U (DFT + U) calculations to explore the energetics of various defects in UO{sub 2}, i.e., noble gases (He, Ne, Ar, Kr, Xe), Schottky defects, and the interaction between these defects. We found the following: (1) collinear antiferromagnetic UO{sub 2} has an energy-lowering distortion of the oxygen sublattice from ideal fluorite positions; (2) DFT + U qualitatively affects the formation volume of Schottky defect clusters in UO{sub 2} (without U the formation volume is negative, but including U the formation volume is positive); (3) the configuration of the Schottky defect cluster is dictated by a competition between electrostatic and surface energy effects; (4) the incorporation energy of inserting noble gas atoms into an interstitial site has a strong dependence on the volume of the noble gas atom, corresponding to the strain it causes in the interstitial site, from He (0.98 eV) to Xe (9.73 eV); (5) the energetics of each of the noble gas atoms incorporated in Schottky defects show strong favorable binding, due to strain relief associated with moving the noble gas atom from the highly strained interstitial position into the vacant space of the Schottky defect; and (6) formore » argon, krypton, and xenon, the binding energy of a noble gas impurity with the Schottky defect is larger than the formation energy of a Schottky defect, thereby making the formation of Schottky defects thermodynamically favorable in the presence of these large impurities.« less

Authors:
;  [1]
  1. Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States)
Publication Date:
OSTI Identifier:
21596890
Resource Type:
Journal Article
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 84; Journal Issue: 13; Other Information: DOI: 10.1103/PhysRevB.84.134111; (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1098-0121
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANTIFERROMAGNETISM; ARGON; BINDING ENERGY; CRYSTAL DEFECTS; DENSITY FUNCTIONAL METHOD; FLUORITE; FORMATION HEAT; HELIUM; IMPURITIES; INCLUSIONS; INTERACTIONS; INTERSTITIALS; KRYPTON; NEON; OXYGEN; SCHOTTKY DEFECTS; SURFACE ENERGY; URANIUM DIOXIDE; XENON; ACTINIDE COMPOUNDS; CALCULATION METHODS; CHALCOGENIDES; CRYSTAL STRUCTURE; ELEMENTS; ENERGY; ENTHALPY; FLUIDS; FREE ENERGY; GASES; HALIDE MINERALS; MAGNETISM; MINERALS; NONMETALS; OXIDES; OXYGEN COMPOUNDS; PHYSICAL PROPERTIES; POINT DEFECTS; RARE GASES; REACTION HEAT; SURFACE PROPERTIES; THERMODYNAMIC PROPERTIES; URANIUM COMPOUNDS; URANIUM OXIDES; VACANCIES; VARIATIONAL METHODS

Citation Formats

Thompson, Alexander E., and Wolverton, C. First-principles study of noble gas impurities and defects in UO{sub 2}. United States: N. p., 2011. Web. doi:10.1103/PHYSREVB.84.134111.
Thompson, Alexander E., & Wolverton, C. First-principles study of noble gas impurities and defects in UO{sub 2}. United States. doi:10.1103/PHYSREVB.84.134111.
Thompson, Alexander E., and Wolverton, C. Sat . "First-principles study of noble gas impurities and defects in UO{sub 2}". United States. doi:10.1103/PHYSREVB.84.134111.
@article{osti_21596890,
title = {First-principles study of noble gas impurities and defects in UO{sub 2}},
author = {Thompson, Alexander E. and Wolverton, C.},
abstractNote = {We performed a series of density functional theory + U (DFT + U) calculations to explore the energetics of various defects in UO{sub 2}, i.e., noble gases (He, Ne, Ar, Kr, Xe), Schottky defects, and the interaction between these defects. We found the following: (1) collinear antiferromagnetic UO{sub 2} has an energy-lowering distortion of the oxygen sublattice from ideal fluorite positions; (2) DFT + U qualitatively affects the formation volume of Schottky defect clusters in UO{sub 2} (without U the formation volume is negative, but including U the formation volume is positive); (3) the configuration of the Schottky defect cluster is dictated by a competition between electrostatic and surface energy effects; (4) the incorporation energy of inserting noble gas atoms into an interstitial site has a strong dependence on the volume of the noble gas atom, corresponding to the strain it causes in the interstitial site, from He (0.98 eV) to Xe (9.73 eV); (5) the energetics of each of the noble gas atoms incorporated in Schottky defects show strong favorable binding, due to strain relief associated with moving the noble gas atom from the highly strained interstitial position into the vacant space of the Schottky defect; and (6) for argon, krypton, and xenon, the binding energy of a noble gas impurity with the Schottky defect is larger than the formation energy of a Schottky defect, thereby making the formation of Schottky defects thermodynamically favorable in the presence of these large impurities.},
doi = {10.1103/PHYSREVB.84.134111},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
issn = {1098-0121},
number = 13,
volume = 84,
place = {United States},
year = {2011},
month = {10}
}