Melt-Growth Joining of Superconductive YBCO Crystals with YBCO/Ag Insert

Melt/growth mechanism and interfacial reaction of YBCO superconductive oxide with molten Ag and YBCO/Ag composite were analyzed to clarify the best fabricating condition of YBCO crystals junction.The peritectic temperature of YBCO(liquid+Y2BaCuO5(Y211)→YBa2Cu3O7−x(Y123)) was lowered toward 1242(±2) K from 1280 K by the addition of Ag, and Y123 phase dissolved into liquid(containing Ag+)+Y211 phases above 1244 K. Therefore Ag and YBCO/Ag composites were used as the inserted low-melting point materials for Y123 crystals. The surface layer of YBCO crystal was melted due to Ag diffusion from inserted YBCO/Ag into the crystals. By cooling the joint under 1240 K, Y123 crystals developed from base YBCO and a superconductive joint was obtained.It was clarified that Ag diffuses from inserted YBCO/Ag composite into YBCO crystals mainly along Y123-Y211 boundaries.