STRUCTURAL CHARACTERIZATION OF THE AG-YBA2CU3O7-X INTERFACE

Silver contacts to the high critical temperature (T(c)) superconductor YBa2Cu3O7-x (YBCO) are characterized using high resolution transmission electron microscopy (HRTEM). Observations of the interfacial regions reveal that Ag bonds to YBCO without any intermediate phase formation but with a preferred orientation relationship, in which the close packed planes and directions of the metal are parallel to those of the superconductor. The formation of (111)Ag interfaces and facets are also strongly favored during deposition. The as-deposited Ag film exhibits a granular morphology and a high twin density, especially when the surface of YBCO is corrugated and structurally unstable. Annealing of the Ag-YBCO interface results in measurable grain growth and a decrease in the density of structural defects within the deposited Ag. At regions where the surface of YBCO is not flat, however, there is precipitation of isolated Ag-bearing particles.