Melt processing of bulk high Tc superconductors and their application

This paper reports on Melt-Powder-Melt-Growth (MPMG) process which results in high Jc for bulk Y-Ba-Cu-O superconductors. The Y-Ba-Cu-O pellets or powders are melt-quenched. The quenched plates are crushed into powder and mixed well. The powder is then compacted into desired shapes and remelted again and slowly cooled in thermal gradient. When the starting composition is changed from the 1:2:3 stoichiometry toward the Y:BaCuO5(211) rich region, the 211 inclusions can be dispersed in the YBa2Cu3Ox matrix,which contributes to the increase in both flux pinning force and fracture toughness. A Jc value exceeding 3 x 108 A/m2 has been achieved at 77K and 1T. Another attractive feature of the MPMG process is that other component such as fine Ag powders can be added during solid state mixing