Sapphire was compressed at 1400C to activate basal slip, and the core structure of introduced basal dislocations was directly observed by high-resolution transmission electron microscopy from a direction parallel to the dislocation line. It was confirmed that the basal dislocation dissociates into two half partial dislocations by the self-climb mechanism as suggested in a previous report. The 2 partials separated with a certain distance along the [00•1] direction, which was normal to the glide plane. On the other hand, it was found that glide dissociation was not developed in the basal dislocation. This result implied that after the glide motion of the basal dislocation had stopped, glide dissociation makes a change to climb dissociation in the core of the dislocation.

Direct Observation of Basal Dislocation in Sapphire by HRTEM. A.Nakamura, T.Yamamoto, Y.Ikuhara: Acta Materialia, 2002, 50[1], 101-8