Molecular dynamics study of UO₂ symmetric tilt grain boundaries around 001 axis

Molecular dynamics and CRG empirical potential are used in this work to study the symmetrical tilt grain boundaries around the [001] axis in UO₂. The analysis of atomic structures obtained by simulation shows excellent agreement with the Read and Schokley model (Read WT, Shockley W. Dislocation Models of Crystal Grain Boundaries. Physical Review. 1950;78:275) predicting the existence of regular dislocations in these grain boundaries. We calculated their energy of formation and cleavage as well as the energy of formation of Schottky defects and incorporation of xenon and krypton atoms in their proximity. This allowed us to determine how these properties evolve for this series of grain boundaries presenting similar geometric characteristics, as a function of the misorientation angle. In addition, the boundary between small and large misorientation grain boundaries has been determined around 20 degrees, close to the value of 15 degrees reported in literature. (authors)