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Title: Computational study of the energetics and defect clustering tendencies for Y- and La-doped UO2

The energetics and defect-ordering tendencies in solid solutions of uoritestructured UO2 with trivalent rare earth cations (M3+=Y, La) are investigated computationally using a combination of ionic-pair-potential and densityfunctional- theory (DFT) based methods. Calculated enthalpies of formation with respect to constituent oxides show higher energetic stability for La solid solutions relative to Y, consistent with the di erences in experimentally measured solubility limits for the two systems. Additionally, calculations performed for di erent atomic con gurations show a preference for reduced (increased) oxygen vacancy coordination around La (Y) dopants. The current results are shown to be qualitatively consistent with related calculations and calorimetry measurements in other trivalent-doped uorite-structured oxides, which show a tendency for increasing stability and increasing preference for higher oxygen coordination with increasing size of the trivalent impurity. The implications of these results are discussed in the context of the e ect of trivalent impurities on oxygen-ion mobilities in UO2, which are relevant to the understanding of experimental observations concerning the e ect of trivalent ssion products on oxidative corrosion rates of spent nuclear fuel.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Engineering
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical Sciences Division
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Physical and Life Science Directorate
  4. Univ. of California, Davis, CA (United States). Nanomaterials in the Environment, Agriculture, and Technology Organized Research Unit (NEAT ORU), Peter A. Rock Thermochemistry Lab.
  5. Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Engineering; Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science
Publication Date:
OSTI Identifier:
1305821
Report Number(s):
LLNL-JRNL--648918
Journal ID: ISSN 1359-6454
Grant/Contract Number:
AC52-07NA27344; AC02-05CH11231; SC0001089
Type:
Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 78; Journal Issue: C; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Research Org:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY Oxygen vacancy; Formation enthalpy; Pyrochlore; DFT