Preparation of YBa2Cu3O7-x -based superconductors by means of glass-technological methods

Abstract

The potential usefulness of glass-technological procedures for the preparation of oxidic high-temperature superconductors is emphasized in general. Exemplarily, samples in the system YBa2Cu3O7-x have been produced by melt processing and subsequent annealing steps. Moreover, network formers have been added to the base system and their influence on the properties of the products has been investigated. The samples have been characterized by x-ray diffraction and scanning electron microscopy as well as by magnetical and electrical measurements. After incorporation of B2O3, specimens could be obtained with magnetically determined onset temperatures of 55 to 85 K, depending on the annealing procedure. These values correspond to those of the melt-processed pure YBa2Cu3O7-x material. The glass ceramic samples of the system CuO-BaO-Y2O3-B2O3 exhibit a densified microstructure and an enhanced mechanical strength. On the other hand, materials prepared in this way did not show electrical long-range superconductivity, presumably due to insufficient percolation of the superconducting crystals. Information is also presented concerning specimens with fluorophosphate as a glass-forming additive which were prepared, too.