〈110〉{1̄10} edge dislocations in strontium titanate: Charged vs neutral, glide vs climb

The ductile deformation of strontium titanate SrTiO${}_3$${}_3$ at low temperature ($T⪅1000$$T⪅1000$ K) is commonly associated with the activity of dislocations gliding in $\left\{110\right\}$$\left\{110\right\}$ slip planes. While dislocations with pure screw character keep essentially the same dissociated core structure in the whole temperature range, dislocations with edge character may adopt different atomic configurations, associated with different charge states and different mobilities. In this work we use atomic-scale simulations to investigate the core structure of charged and neutral edge dislocations. We report a new possible dislocation core that is charge-neutral, dissociated, and with the lowest Peierls stress reported so far, thus making it an efficient component of plastic deformation. In comparison, dislocations carrying a positive charge are slightly less mobile, while those with negative charge have a very low mobility. Our results indicate that glide of charge-neutral dislocations is favoured, and that they may locally acquire a charge by interacting with vacancies all while remaining glissile. Finally, we investigate edge dislocations that are dissociated in their climb plane, and confirm that they are energetically more favourable than their glissile counterparts. Computing the activation energy for the core transformation provides insight into the ductile–brittle transition.