Jog (dislocations)

Jog describes the turns of a dislocation line inside a crystal structure. A dislocation line is rarely uniformly straight as in the figure, often containing many curves and/or steps to facilitate movement through the crystal in incremental amounts, rather than shifting the entire line at once. One of these step types is a jog, the other is a kink. However, both are typically referred to as jogs, which can be a source of confusion.

Segments of dislocation line that have a component of their sense vector normal to the glide plane are termed jogs.^[1] See image for the definitions of the sense vector and the glide plane. Segments of dislocation line that do not leave the original glide plane are termed kinks.

Jogs are often very immobile compared to kinks, and require diffusion of crystallographic defects like vacancies or interstitial atoms to climb. They are not capable of glide (movement in the glide plane) because the direction of motion is in the plane normal direction, not on the plane itself as with kinks.

Schematic representation of an edge dislocation in a crystal lattice. The yellow plane is the glide plane, the vector u is the dislocation sense vector, b is the Burgers vector. When the dislocation moves from left to right through the crystal, the lower half of the crystal has moved one Burgers vector length to the left, relative to the upper half.

Notes

1. Hirth, Lothe, 1982

Hirth, J. P., Lothe, J., Theory of Dislocations, 2nd edition, Krieger Publishing Company, Malabar, Florida, 1982 reprint 1992, page 261