Observation of a novel stacking-fault nucleation mechanism in melt-textured YBa₂Cu₃O₇

Abstract

The dislocation substructure of melt-textured YBa₂Cu₃O₇-Y2BaCuO₅ composites deformed under uniaxial compressive stress and a superposed gaseous confining pressure has been investigated by transmission electron microscopy. Observations reveal the generation of perfect dislocations in (001) as well as out of this plane. Screw segments of the latter lying on (001) are seen to act as Frank-Read sources for ⅙ 〈301〉 partials bounding YBa₂Cu₄O₈-type stacking faults, according to a mechanism previously anticipated from theoretical considerations by one of the present authors.