Influences of Zr, Ce and Ba fission products on the surface properties of UO2: Atomistic simulations

HX Xiao and CS Long and XF Tian and HS Chen, SURFACE SCIENCE, 649, 1-6 (2016).

DOI: 10.1016/j.susc.2016.01.014

Molecular dynamics (MD) simulations with a shell-core model have been carried out to investigate the influences of Zr, Ce and Ba fission products on the surface properties of UO2. Simulation results indicate that (i) the presence of these fission products will change the surface energy of three low-index surfaces in UO2; (ii) the individual addition of Ce has no significant effect on the surface energy, while the individual addition of Ba will dramatically decrease the surface energy of UO2 by approximately 18% on (100) surface, 7% on (110) surface and 9% on (111) surface with the Ba contents ranging from 0 to 12.5 mol% at 300 K, which is obviously contrary to the Zr; (iii) the combined additions of Zr, Ce and Ba fission products will continuously increase the surface energy of UO2 (100), (110) and (111) surfaces; (iv) the structures of the three low-index surfaces in pure UO2 as well as U-0.8(Zr,Ce, Ba)(0.2)O-2 are dramatically disturbed after the free relaxation; (v) The nearest O atoms move towards the Zr and Ce atoms center by about 0.21 angstrom and 0.12 angstrom but move away from the Ba atom center by about 0.27 angstrom. (C) 2016 Elsevier B.V. All rights reserved.

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