Dislocations in the fluorite structure

The structures of dislocations on the primary and secondary slip systems in crystals with the fluorite structure are investigated. It is shown that the edge dislocation on the primary system can adopt either a charged or a jogged configuration; the most likely form (for calcium fluoride) is intermediate between these extremes, i.e. a series of adjacent like charges terminating in a ’half’ jog and followed by a series of opposite like charges, etc. The screw dislocation and the edge dislocation on the secondary system are uncharged. The velocities of dislocations are measured and the screw dislocations are found to move faster than the edge. This observation is associated with the unusual nature of the edge dislocation.