Process parameters, orientation, and functional properties of melt-processed bulk Y-Ba-Cu-O superconductors

摘要

This study compared the microstructure, texturing, and functional properties (critical currents) of YBa(sub 2)Cu(sub 3)O(sub 7(minus)x)-based bulk pellets that were prepared by the quench-melt-growth-process (QMGP), melt-textured growth (MTG), and conventional solid-state reaction (SSR) approaches. Using two X-ray diffraction (XRD) methods, (theta)-2(theta), and rocking curves, the authors found that the individual grains of two melt-processed pellets exhibited remarkable preferred orientational alignment (best rocking curve width = 3.2(degree)). However, the direction of the preferred orientation among the grains was random. Among the three types of bulk materials studied, the QMGP sample was found to have the best J(sub c) values, (approx) 4,500 A/cm(sup 2) at 77 K in a field of 2 kG, as determined from SQUID magnetic data.