New multi-seeding method of RE-Ba-Cu-O superconductor

We have developed a new multi-seeding method, multi-seeded seamless bulk (MUSLE) technique, for improving a problem of the conventional multi-seeding method, i.e. the existence of the excluded non-supercondcting phases (liquid phases and segregated RE211 phases) at the grain boundaries in the bulk superconductor. It is the basic concept of this technique that the precursor is composed of two or more RE-Ba-Cu-O layers with different peritectic temperatures. Thereby, the directions of the crystal growth from the seed crystals can be controlled. RE-Ba-Cu-O superconductors were fabricated by the MUSLE technique with four seeds. The trapped field distribution obtained at 77 K showed a single peak with a value of 0.9 T, indicating that the MUSLE technique is effective in eliminating the excluded phases formed at the grain boundaries in the multi-seeded bulk superconductor. We suggest that the elimination of the excluded phases can be explained by the seed crystal proximity effect. (C) 2002 Elsevier Science B.V. All rights reserved.