High-Resolution Electron Microscopy of Planer Defects and Dislocation in Ba2YCu3Oy

Abstract
Two types of planar defects in Ba2YCu3O y (y is around 6.9), previously reported [Y. Matsui et al.: Jpn. J. Appl. Phys. 26 (1987) L777] are re-examined by high-resolution transmission electron microscopy. The first is due to additional [CuO] one-dimensional chains inserted in the basal plane to form double chains, and the second to additional [CuO2] layers inserted near the Y layers to form double pyramids. The local formation of the latter type of planar defect may possibly be the origin of the edge-dislocation with Burgers vector [100] or [010].