Investigation of cation self-diffusion mechanisms in UO2 +/- x using molecular dynamics / Boyarchenkov A. S.,Potashnikov S. I.,Nekrasov K. A.,Kupryazhkin A. Ya. // JOURNAL OF NUCLEAR MATERIALS. - 2013. - V. 442, l. 1-3. - P. 148-161.

ISSN/EISSN:

0022-3115 / 1873-4820

Type:

Article

Abstract:

This article is devoted to investigation of cation self-diffusion mechanisms, taking place in UO2, UO2-x, and UO2-x crystals simulated under periodic (PBC) and isolated (IBC) boundary conditions using the method of molecular dynamics in the approximation of rigid ions and pair interactions. It is shown that under PBC the cations diffuse via an exchange mechanism (with the formation of Frenkel defects) with activation energy of 15-22 eV, while under IBC there is competition between the exchange and vacancy (via Schottky defects) diffusion mechanisms, which give the effective activation energy of 11-13 eV near the melting temperature of the simulated UO2.00 nanocrystals. Vacancy diffusion with lower activation energy of 6-7 eV was dominant in the non-stoichiometric crystals UO2.10, UO2.15 and UO1.85. Observations showed that a cation vacancy is accompanied by different number of anion vacancies depending on the deviation from stoichiometry: no vacancies in UO2.15, single vacancy in UO2.00 and four vacancies in UO1.85. The corresponding law of mass action formulas derived within the Lidiard-Matzke model allowed explaining the obtained activation energies and predicting a change in the activation energy within the temperature range of the superionic phase transition. The diffusion of cations on the surface of nanocrystals had activation energy of 3.1-3.6 eV. (C) 2013 Elsevier B.V. All rights reserved.

Author keywords:

URANIUM-DIOXIDE; THERMAL-CONDUCTIVITY; OXYGEN DIFFUSION; ACTINIDE OXIDES; POINT-DEFECTS; UO2; SIMULATION; NANOCRYSTALS; POTENTIALS; ENERGETICS

DOI:

10.1016/j.jnucmat.2013.08.030

Web of Science ID:

ISI:000328175400019

Соавторы в МНС:

Другие поля

Поле	Значение
Month	NOV
Publisher	ELSEVIER SCIENCE BV
Address	PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
Language	English
EISSN	1873-4820
Keywords-Plus	URANIUM-DIOXIDE; THERMAL-CONDUCTIVITY; OXYGEN DIFFUSION; ACTINIDE OXIDES; POINT-DEFECTS; UO2; SIMULATION; NANOCRYSTALS; POTENTIALS; ENERGETICS
Research-Areas	Materials Science; Nuclear Science \& Technology
Web-of-Science-Categories	Materials Science, Multidisciplinary; Nuclear Science \& Technology
Author-Email	boyarchenkov@gmail.com potashnikov@gmail.com kirillnkr@mail.ru kupr@dpt.ustu.ru
ResearcherID-Numbers	Albe, Karsten/F-1139-2011
ORCID-Numbers	Boyarchenkov, Anton/0000-0002-4083-9201
Number-of-Cited-References	60
Usage-Count-Last-180-days	7
Usage-Count-Since-2013	63
Journal-ISO	J. Nucl. Mater.
Doc-Delivery-Number	268MQ