It was noted that in sapphire single crystals with a [00▪1] orientation and in directionally solidified eutectic ceramic composites which contained topologically continuous Al2O3 components with nearly perfect [00▪1] growth textures, the creep resistance at 1400 to 1800C resulted from the sessile nature of the dislocations of the pyramidal system. This was the only system to produce creep in this orientation. The results of a molecular dynamics simulation of the core of the pyramidal edge dislocation were presented here. These demonstrated its sessile nature, and indicated that the only possibility for creep in this orientation was the climb of such dislocations.

Pyramidal Edge Dislocation Cores in Sapphire. J.Chang, C.T.Bodur, A.S.Argon: Philosophical Magazine Letters, 2003, 83[11], 659-66