Effects of liquid source mass and slow-cooling time on the infiltration growth of single-grain Y–Ba–Cu–O bulk superconductors

The effects of liquid source (LS) mass and slow-cooling (SC) time on the infiltration growth of the YBCO single grains were investigated. Experimental observations indicated that, the growth rate of YBa2Cu3O7−x crystal increased with the increasing mass of the used LS pellet, and the optimal LS mass for IG process of Y2BaCuO5 preform bulk (12 g) was identified as 20 g. In addition, it was also found that the YBCO single grains grew much larger with the increasing SC time, and finally up to the whole sample size at a SC time 64 h. A crooked a/c growth sector boundary was observed in the cross section of the YBCO single grain grown for 48 h, which resulted from the variations of growth rate along different directions during the SC process. The results can help us develop more optimized IG process to fabricate YBCO single grains more economically and efficiently.

► YBCO single grains were fabricated in air using a modified IG technique.
► Growth rate of Y-123 crystal increased with the increasing liquid source mass.
► The optimal liquid source mass for IG process of a Y-211 preform (12 g) was identified as 20 g.
► YBCO single grains grew much larger with the increasing slow-cooling time.
► A crooked a/c-GSB was observed in the cross section of the YBCO sample grown for 48 h.