A new method for multiseeding RE-Ba-Cu-O superconductor

We have developed a new multiseeding method, the MUSLE (MUlti-Seeded seamLEss bulk) technique, for alleviating a problem of the conventional multiseeding method, i.e. the existence of excluded non-superconducting phases (liquid phases and segregated RE211 phases) at the grain boundaries orientated by the multiple seeds in the bulk superconductor. The basic concept of this technique is that the precursor is composed of two or more RE-Ba-Cu-O layers with different peritectic temperatures. In order to study the superconducting prospects for MUSLE bulk, RE-Ba-Cu-O bulk superconductors of various sizes up to 100 mm in diameter were produced by the MUSLE technique. All trapped field distributions for the RE-Ba-Cu-O bulk superconductors had a single peak. For the 46 mm diameter MUSLE bulk, J(c) (B) across the multiseed-orientated grain boundary was comparable to that in the grain. The misorientation angle of the c-axis between the multi seed-orientated grains was approximately 3degrees-7degrees in this sample, whereas each J(c)(B) for the specimens across the multiseed-orientated grain boundary has the same level. We also estimated the macro-J(c) flow in bulk superconductors through the peak values of the trapped fields. The macro-J(c) for the MUSLE bulk was larger than that for the single-seeded bulk at sizes greater than 65 mm diameter.