Please use this identifier to cite or link to this item: http://hdl.handle.net/10995/27142
Title: High-precision molecular dynamics simulation of UO2-PuO 2: Anion self-diffusion in UO2
Authors: Potashnikov, S. I.
Boyarchenkov, A. S.
Nekrasov, K. A.
Kupryazhkin, A. Y.
Issue Date: 2013
Citation: High-precision molecular dynamics simulation of UO2-PuO 2: Anion self-diffusion in UO2 / S. I. Potashnikov, A. S. Boyarchenkov, K. A. Nekrasov [et al.] // Journal of Nuclear Materials. — 2013. — Vol. 433. — № 1-3. — P. 215-226.
Abstract: Our series of articles is devoted to high-precision molecular dynamics simulation of mixed actinide-oxide (MOX) fuel in the approximation of rigid ions and pair interactions (RIPI) using high-performance graphics processors (GPU). In this article we study self-diffusion mechanisms of oxygen anions in uranium dioxide (UO2) with the 10 recent and widely used sets of interatomic pair potentials (SPP) under periodic (PBC) and isolated (IBC) boundary conditions. Wide range of measured diffusion coefficients (from 10-3 cm2/s at melting point down to 10-12 cm2/s at 1400 K) made possible a direct comparison (without extrapolation) of the simulation results with the experimental data, which have been known only at low temperatures (T < 1500 K). A highly detailed (with the temperature step of 1 K) calculation of the diffusion coefficient allowed us to plot temperature dependences of the diffusion activation energy and its derivative, both of which show a wide (∼1000 K) superionic transition region confirming the broad λ-peaks of heat capacity obtained by us earlier. It is shown that regardless of SPP the anion self-diffusion in model crystals without surface or artificially embedded defects goes on via exchange mechanism, rather than interstitial or vacancy mechanisms suggested by the previous works. The activation energy of exchange diffusion turned out to coincide with the anti-Frenkel defect formation energy calculated by the lattice statics. © 2012 Elsevier B.V. All rights reserved.
Keywords: DEFECT FORMATION ENERGIES
DIFFUSION ACTIVATION ENERGY
EMBEDDED DEFECTS
EXCHANGE DIFFUSION
EXCHANGE MECHANISM
GRAPHICS PROCESSOR
HIGH-PRECISION
LATTICE STATICS
LOW TEMPERATURES
MOLECULAR DYNAMICS SIMULATIONS
OXYGEN ANION
PAIR INTERACTIONS
PAIR POTENTIAL
SELF-DIFFUSION
SUPERIONIC TRANSITION
TEMPERATURE DEPENDENCE
VACANCY MECHANISMS
ACTIVATION ENERGY
APPROXIMATION THEORY
CRYSTAL DEFECTS
IONS
MOLECULAR DYNAMICS
MOLECULAR MECHANICS
SURFACE DEFECTS
DIFFUSION
URI: http://hdl.handle.net/10995/27142
SCOPUS ID: 84867895212
WOS ID: WOS:000316153800029
PURE ID: 895948
ISSN: 0022-3115
DOI: 10.1016/j.jnucmat.2012.08.033
Appears in Collections:Научные публикации, проиндексированные в SCOPUS и WoS CC

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