Processing and Properties of Bulk Textured YBa2Cu3Ox

We present our work on the preparation and studies of bulk samples of the YBa2Cu3Ox superconductor that have controlled grain orientation. The effect of the degree of grain alignment on physical properties with emphasis on the critical current densities is described. First, the processing was based on the standard solid state reaction method. We find that repeating the steps of this method leads to higher degree of orientation, until a saturation is reached. X-ray measurements show the preferred orientation of the grains on the surface of the samples with their c-crystallographic axis parallel to the compression axis. Scanning electron microscopy photographs of internal surfaces of samples that were broken indicates that this preferred orientation extends throughout the bulk of the samples with up to ~45% of the microcrystallites aligned. We measure the preferred orientation of the grains inside the samples with a polarized Raman spectroscopy technique that we have developed. Critical current (Jc) experiments show the dependence of the critical current densities on the degree of alignment. At 77K and ambient field, Jc increases with the preferred orientation by a factor of three. Application of melt-growth on pre-oriented samples results to an order of magnitude increase in the average size of the microcrystals.