It was recalled that melt-processed samples of this superconductor exhibited a superior levitation behavior, due to the presence of numerous flux-pinning entities such as twins, dislocations, and Cu4Ba2YO8 stacking faults; which were concentrated mainly around trapped CuBaY2O5 inclusions. In order to understand the formation of the Cu4Ba2YO8 stacking faults, melt-textured samples of Cu3Ba2YO7 were examined. It was found that no Cu4Ba2YO8 stacking fault was observed around CuBaY2O5 in a tetragonal Cu3Ba2YO7 matrix. After oxygenation, Cu4Ba2YO8 stacking faults and Ba-Cu-O platelets formed mainly at the Cu3Ba2YO7/ CuBaY2O5 interface, extended into the Cu3Ba2YO7 matrix, and developed along the [100] and [010] directions of the Cu3Ba2YO7. The defect density depended upon the oxygenation time; thus indicating that the tetragonal-to-orthorhombic phase transformation could be attributed to the formation of a platelet structure; including Cu4Ba2YO8 stacking faults.

C.J.Kim, I.H.Kuk, G.W.Hong: Superlattices and Microstructures, 1997, 21[A], 63-70