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arXiv · 1103.6010

Molecular dynamics simulation of UO2 nanocrystals surface

A. S. Boyarchenkov·S. I. Potashnikov·K. A. Nekrasov·A. Ya. Kupryazhkin
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Abstract

In this article we investigated surface of nanocrystals (NC) of uranium dioxide (UO2) using molecular dynamics (MD) under isolated (non-periodic) boundary conditions with the approximation of pair potentials and rigid ions. It is shown that a cubic shape of the model NCs is metastable and the stable equilibrium is reached in the process of structural relaxation to the octahedral shape over a time of 1000 ns (200 million MD steps), which increases with the size of NC. We measured the size dependences of the lattice parameter and the surface energy density for NC of cubic and octahedral shape with volume up to 1000 nm3 (50000 particles) at temperatures of 2200K and 2300K. For the surfaces {100} and {111} we obtained the energy density σ100=1.602\pm0.016 J/m^2, σ111=1.137\pm0.032 J/m^2 and surface tension constant γ111=0.875\pm0.008 J/m^2. The resulting ratio of σ100/σ111=1.408\pm0.042 within the error coincides with the experimental value of 1.42\pm0.05 measured for microscopic cavities in monocrystals of UO2.

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A. S. Boyarchenkov, S. I. Potashnikov, K. A. Nekrasov, A. Ya. Kupryazhkin. 2011-03-30. Molecular dynamics simulation of UO2 nanocrystals surface. https://doi.org/10.1016/j.jnucmat.2011.11.030

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