A STUDY ON THE MICROSTRUCTURAL DEFECTS ALONG THE A-B PLANE IN THE MELT-TEXTURED YBA2CU3OY SUPERCONDUCTOR

The microstructural defects of the melt-textured growth (MTG) YBa2Cu3Oy superconductor were studied by transmission electron microscopy using a sample prepared such that the electron beam was parallel to the a-b plane of the material. A special planar defect with a highly disordered atomic arrangement in it was observed. A large density of defects (10(9)-10(10) cm-2), in the forms of dislocations and stacking faults, was found in the material. [001]-type edge dislocations, and localised crystal-plane distortion with a surrounding region of strain field were also observed. Many of the defects observed may act as flux-pinning centres and thus increase the critical current density of the superconductor. In addition, stacking faults which were identified as the YBa2Cu4O8 (124) phase were found. Some amorphous layers were also noted on grain boundaries.