Grain boundaries in sintered YBa₂Cu₃O_7–δ

High-resolution electron microscopy has been carried out on grain boundaries of 92% dense YBa₂Cu₃O_7-δ in the tetragonal form. Grain boundaries were found to be predominantly parallel to (001) of one of the adjacent grains. No amorphous interlayer was observed at the grain boundaries. At some grain boundaries highly localized strains were detected.