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Title: Vacancy–Vacancy Interaction Induced Oxygen Diffusivity Enhancement in Undoped Nonstoichiometric Ceria

In this paper, molecular dynamics simulations and molecular static calculations have been used to systematically study oxygen vacancy transport in undoped nonstoichiometric ceria. A strong oxygen diffusivity enhancement appears in the vacancy concentration range of 2–4% over the temperature range from 1000 to 2000 K. An Arrhenius ion diffusion mechanism by vacancy hopping along the (100) direction is unambiguously identified, and an increasing trend of both the oxygen migration barrier and the prefactor with increasing vacancy concentration is observed. Within the framework of classical diffusion theory, a weak concentration dependence of the prefactor in oxygen vacancy migration is shown to be crucial for explaining the unusual fast oxygen ion migration in the low concentration range and consequently the appearance of a maximum in oxygen diffusivity. Finally, a representative (100) direction interaction model is constructed to identify long-range vacancy–vacancy interaction as the structural origin of the positive correlation between oxygen migration barrier and vacancy concentration.
Authors:
 [1] ;  [2] ;  [2]
  1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering
  2. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
Publication Date:
OSTI Identifier:
1265538
Grant/Contract Number:
AC05-00OR22725; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 119; Journal Issue: 23; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
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)
Contributing Orgs:
Univ. of Tennessee, Knoxville, TN (United States)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE Ceria; Vacancy; Oxygen Diffusivity