The predicted shapes of voids and Xe bubbles in UO2

Morphology is a fundamental attribute when investigating voids and bubbles in
. This study uses molecular dynamics and Monte Carlo simulations to predict the lowest energy shapes for voids and bubbles in
. The energies of the and surfaces have been calculated and used to predict the equilibrium void shape from Wulff construction. This equilibrium shape is compared to low energy faceted voids exhibiting different relative proportions of each family of terminating surfaces. It is found that the equilibrium Wulff shape does not represent the lowest energy morphology for nm void sizes at temperatures between 300 K and 1200 K. Furthermore, the lowest energy faceted voids are slightly more energetically favourable than spherical voids, and as Xe is added, and bubble pressure increases, the faceted morphology becomes even more favourable than the spherical shape