Single grain RE-Ba-Cu-O ((RE)BCO, where RE was a rare earth element or yttrium) bulk superconducting materials have significant potential for a variety of engineering applications due to their ability to trap high magnetic fields. However, it was well known that the presence of grain boundaries coupled with a high angle of misorientation (typically 5°) significantly reduces the critical current density, Jc, in all forms of high temperature superconducting materials. It was of considerable fundamental and technological interest, therefore, to investigate the grain boundary properties of bulk, film and tape (RE)BCO. A successful multi-seeding technique was described for the fabrication of fully-aligned artificial (0° misalignment) grain boundaries within large grain YBCO bulk superconductors using bridge-shaped seeds. The microstructure and critical current densities of the grain boundaries produced by this technique were studied in detail.

Properties of Grain Boundaries in Bulk, Melt Processed Y-Ba-Cu-O Fabricated Using Bridge-Shaped Seeds. Y.H.Shi, J.H.Durrell, A.R.Dennis, N.H.Babu, C.E.Mancini, D.A.Cardwell: Superconductor Science and Technology, 2012, 25[4], 045006