Effects of Y2BaCuO5 content and the initial temperature of slow-cooling on the growth of YBCO bulk

In order to grow large mono-domain YBa2Cu3O7−δ bulk in the tubular furnace, the effect of Y2BaCuO5 (Y211) content and initial temperature of the slow-cooling process on the growth of YBa2Cu3O7−δ (Y123) bulk has been investigated. Single grain Y123 bulk samples with 20 mol% and 30 mol% Y211 addition have higher original crystallization temperature than that with 40 mol% Y211; however, the melt-textured growth rate of the single domain seems to be faster for the system with higher Y211 concentrations. In addition, it seems that the crystal growth of YBCO is extremely sensitive to the initial temperature of slow-cooling. The optimal initial temperature of slow-cooling process, which should be chosen according to the Y211 phase content, has been brought to the fore in the growth of large grain bulk. The above data is very useful for the fabrication of large grain (RE)-Ba-Cu-O bulk, and a group of YBCO single domain samples with diameter of 53 mm have been successfully produced, all of which present excellent magnetic levitation performance in the axial direction.