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Title: Theoretical investigation of thermodynamic stability and mobility of the oxygen vacancy in ThO 2 –UO 2 solid solutions

The thermodynamic stability and the migration energy barriers of oxygen vacancies in ThO 2 –UO 2 solid solutions are investigated by density functional theory calculations. In pure ThO 2, the formation energy of oxygen vacancy is 7.58 eV and 1.46 eV under O rich and O poor conditions, respectively, while its migration energy barrier is 1.97 eV. The addition of UO 2 into ThO 2 significantly decreases the energetics of formation and migration of the oxygen vacancy. Among the range of UO 2-ThO 2 solid solutions studied in this work, UO 2 exhibits the lowest formation energy (5.99 eV and -0.13 eV under O rich and O poor conditions, respectively) and Th 0.25U0 .75O 2 exhibits the lowest migration energy barrier (~ 1 eV). Moreover, by considering chemical potential, the phase diagram of oxygen vacancy as a function of both temperature and oxygen partial pressure is shown, which could help to gain experimental control over oxygen vacancy concentration.
Authors:
 [1] ;  [1] ;  [2] ;  [2]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division; Univ. of Tennessee, Knoxville, TN (United States). Department of Materials Science and Engineering
Publication Date:
Grant/Contract Number:
AC05-00OR22725; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Physical Chemistry Chemical Physics. PCCP (Print)
Additional Journal Information:
Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal Volume: 16; Journal Issue: 46; Journal ID: ISSN 1463-9076
Publisher:
Royal Society of Chemistry
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Thoria; Urania; Oxygen Vacancy
OSTI Identifier:
1163592