An Electron Microscope Study of Defect-free YBa2Cu3O7?x (x » 0.15) with Superconductivity at 93 K

High resolution electron microscopy has been used to characterise sintered preparations of the mixed oxide YBa2Cu307_x (x::::; 0·15). By carefully controlled processing techniques a single phase defect-free orthorhombic structure having excellent characteristics for use as a high temperature superconductor was obtained. Surface structures and an image of a dislocation are included in this study.