Energetics of the break-up of dislocation dipoles into prismatic loops

The energetics of two different models leading to the formation of a row of prismatic loops from the fluctuation and subsequent break-up of dislocation dipoles or elongated dislocation loops have been evaluated as a function of fluctuation amplitude and wavelength. Break-up most likely occurs by spontaneous pinching off of small circular loops at the ends of closed-ended dipoles or elongated loops. The theoretical results agree well with experimental observations of the dislocation substructure in Ti⁴⁺-doped sapphire (α-Al₂O₃) deformed by basal slip.