The role of boundaries in the superconducting properties of sintered YBa2Cu3O7−x

Since the discovery of high critical temperature superconducting oxides, an important factor potentially limiting their technological application has been the typically low value of the critical current density that they can carry. Here are presented the results of a transmission electron microscopy study of sintered YBa2Cu3O7−x aimed primarily at the characterization of those elements of the microstructure responsible for the poor current-carrying capacity in the superconducting state. The observations are further discussed in relation both to the flux pinning characteristics required and to the prospect for controlling the microstructure in order to optimize the properties of this material for technological development.