Atomistic simulation of jog pair in magnesium oxide

Magnesium oxide MgO is known for its ductility, allowed by dislocations which are surprizingly glissile for an oxide ceramic material. However in high-temperature applications, the enhanced diffusion may activate another mechanism: dislocation climb, where a dislocation moves out of its glide plane. This is particularly true when one considers creep conditions, where high temperatures come together with very slow strain rates.

In this work, we investigate dislocation climb in magnesium oxide for the two main slip systems [110](110) by means of atomistic simulation. The edge dislocation core configurations are obtained at different pressuresfrom dislocation dipolar configurations with periodic boundary conditions. Jog pair configurations are constructed by duplicating different dislocation dipole configurations. We determine the formation energy of jog pairs under various pressure conditions, and find that they bear an electric charge. We demonstrate that jog density is low and jog pair nucleation mechanism should be considered to model dislocation climb in MgO.