Processing and properties of high J(sub c) grain boundaries in melt textured YBa2Cu3O(x)

摘要

We have developed a processing method to eliminate secondary phases and to reduce the amount of microcracks at the grain boundaries in melt-textured YBCO superconductors. In this process, a fraction of the liquid phase is removed during melt-texturing which lead to cleaner grain boundaries. These boundaries have been found to carry high currents (30,000 A/sq cm at self field and 1500 A/sq cm at 1.5T) at 77 K in spite of relatively high misorientation angles. Also, the weak dependence of J(sub c) on magnetic field indicates that these grain boundaries are strongly coupled. In addition, the linear I-V characteristics of these samples suggest that flux flow along these boundaries may be the J(sub c) limiting mechanism.