Mobile bend zones in magnesium oxide

Abstract

Bend zones are regions in a crystal across which the lattice is bent; the bend occurs across the whole width of the zone. The lattice bending may be due to flexural glide or an array of discrete bend planes or a single bend plane or combinations of these; the composition of a bend zone may vary along its length. Several examples are given of the conditions under which bend zones form in magnesium oxide. They are able to move through existing dislocation bands as a perturbation of the dislocation arrangement in these bands. They arise in an attempt to accommodate strain due to various phenomena, e.g. grip restraint, dislocation configurations and cracks. Comment is made on their role in crack nucleation and growth.