Self-seeded YBCO welding induced by Ag additives

A new welding procedure for bulk melt-textured YBa2Cu3O7 (YBCO) superconduc ting tiles has been developed leading to high quality joints. The welding a gent consists of a YBCO-Ag composite, which has a peritectic temperature 40 degreesC lower than YBCO. It is shown that through a proper selection of t hermal treatments, the effect of Ag additives can be confined to the immedi ate welding zone, thus allowing a self-seeded growth process of the YBCO/Ag composite initiated at the adjacent solid YBCO crystals. Local magneto-opt ical observations, as well as trapped field measurements produced by circul ating currents in ring samples, reveal that the critical current across the weld joint is as high as that of bulk melt-textured YBCO. (C) 2001 Elsevie r Science B.V. All rights reserved.