Dissociation of dislocation witha/2〈111〉 Burgers vectors in YIG single crystals deformed at high temperature

Abstract

It is shown that dislocations with a/2〈111〉 Burgers vector in yttrium iron garnet (YTG) deformed in compression above 0.8T _M are dissociated into two partials following: a/2〈111〉→a/4〈111〉 + a/4〈111〉. The dissociation mode involves a climb component which renders the glide motion of the dislocation difficult. The dissociation width is not constant and cannot be used to derive a stacking-fault energy intrinsic to the crystal. The variations in width are probably associated with local interactions with point defects. Pure climb motion of the dislocations, consistent with the dissociation, is experimentally observed.