A NEW METHOD FOR SINGLE DOMAIN YBaCuO SUPERCONDUCTORS BY MULTISEEDING

Although large single domain YBCO superconducting bulk can be produced by using the top-seeded melt process, it takes a quite long period for the grain growth because of an extremely low growth rate of YBCO-123 phase. In order to overcome such a problem, the multi-seeded melt growth (MSMG) technique has been developed. However, in the MSMG-processed YBCO samples, grain boundaries formed between two adjacent grains often is weak links. In this paper, we report a new method prepared single domain YBCO bulk by using modified MSMG. The precursor is composed of layers (Layer-A and layer-B) with composition gradient. The composition of layer-A is (Y_ 1-x Gd_x)_ 1.8 Ba_ 2.4 Cu_ 3.4 O_y (x0.1, 0.2) and layer-B is Y_ 1.8 Ba_ 2.4 Cu_ 3.4 O_y. The peritectic temperatures of layer-A is higher than layer-B. Four SBCO seeds with same size and orientations were placed on the layer-A before the melt process. The trapped field distributions for the bulk superconductors prepared by this modified MSMG method showed a single peak, simulate to the top-seeded melt process using single seed, indicating that the sample had single domain structure.