On the dissociation of dislocations in YBa₂CU₃O_7-δ

Abstract

The fine structure of dislocations with (100) Burgers vectors in YBa₂CU₃O_7-δ ceramics were characterized by transmission electron microscopy after various thermomechanical treatments. Dissociation widths are larger after high-temperature treatments, and it is found that, even at room temperature, dissociations of dislocations are associated with a local non-stoichiometry. The dissociation reaction can be written as on the (001) plane; this involves the addition of a CuO layer in the 1:2:3 matrix at the dislocation core. Mechanisms involved in this non-stoichiometric splitting of dislocations are discussed.