The role of uranium chemistry and uranium fission in obtaining ultra-high Jc in textured Y123

When uranium (U) is added to Y123 powders, after texturing the deposits containing U are found to be similar to 300 nm. These deposits act as pinning centres, and increase J(c) by 90% per 0.8 wt% U. Neutron irradiation further increases J(c). Total increases of J(c) by factors of e.g. similar to 30 (at 77 K, 0.25 Tesla), and similar to 15 (at 50 K, 10 Tesla) result. Magnitudes of J(c) are similar to 290 000 A cm(-2) (at 77 K, 0.25 T) and 10(6) A cm(-2) (at 50 K, 0.25 T). The U/n process is not yet optimized. Chemistry, microstructure, radiation effects and cost are discussed.