Direct observation of grain orientation in YBa2Cu3O7-δthin films

Using a recently developed specimen-preparation technique to examine heteroepitactic growth in ceramics, the early development of grain orientation in thin YBa2 Cu3 O7-δ films prepared by pulsed-laser ablation can be determined. The technique involves deposition directly on to a specially prepared electron-transparent substrate. The films are examined during the early stages of growth by transmission electron microscopy. Three different orientations corresponding to different alignments of the c axis of the YBa2 Cu3 O7-delta; unit cell with the MgO substrate could be determined from the particle morphology in the image, but were not detected by selected-area diffraction due to their small size.