ON CRYSTAL ALIGNMENT IN POLYCRYSTALLINE YBCO MATERIALS BASED ON TEM OBSERVATION

Previously, we have observed that parallel lattice fringes show up reg ularly in MTG samples, indicative of good alignment of unit cells in s trips of size similar to 100 nm x a few times 100 nm. We have prepared films (similar to 80 nm) for TEM observation using YBCO material fabr icated by the conventional solid-state reaction method in order to stu dy the crystal texture in a length scale from a few 100 nm down to sim ilar to 3 Angstrom. Parallel lattice fringes are observed to stretch a cross a cross-section similar to 0.3 x 0.5 mu m(2). Cross lattice frin ges intersecting at 90 degrees and 45 degrees are observed as rare eve nts. This result suggests that the degree of alignment in the crystal texture is higher than expected inside a grain of size similar to a fe w mu m.