Structural defects were studied by means of high-resolution electron microscopy, together with multi-slice image simulation. The as-prepared crystals contained several types of structural defect. These included planar defects that consisted of a local structure of Cu5Ba2YO9, with triple Cu-O chains that resulted from the insertion of an extra Cu-O chain at the location of the original double Cu-O chains. There were also planar faults that consisted of thin 90° rotation twins about the c-axis. The layer thickness of the a-c plane domain in the b-c plane domain was equal to half of a unit cell along the c-axis of the host material. Layers of Cu4Ba2YO8 and Cu3Ba2YO7 existed within a given crystal. Also present were edge dislocations with a Burgers vector of b<010> or a<100> on a single Cu-O chain layer, and dislocations with a Burgers vector of ½[110] on double Cu-O chain layers which existed at the boundaries of 90° twins.

K.Hashimoto, M.Akiyoshi, A.Wisniewski, M.L.Jenkins, Y.Toda, T.Yano: Physica C, 1996, 269[1-2], 139-48