Stacked cylindrical ring bulk YBCO superconductor fabricated by top-seeding-melt-growth process

In this study, it is intended to increase the dimension of the superconductors and improve their technological use. For this purpose, samples having different compositions were prepared with Top seeding-melt-growth (TSMG) process by using Y2O3 layer from Y123: Y211: CeO2 powder mixtures and Nd123 was used as seed. Totally ten samples were fabricated in stoichiometric ratios of 1:0:0, 1:0.4:0, 1:0.4:0.1, 1:0.3:0.1, 1:0.2:0.1 as two samples was produced for each composition. Melt-powder-melt-growth (MPMG) processed five samples with 17 % wt. Ag2O added samples were fabricated for welding of TSMG Y123 samples. Appropriate samples for stacking were determined from X-ray diffraction patterns and levitation force results. The samples were welded by thermal process after placing a mass of 2.4 kg on the top surface of the stacked samples. The welded samples were brought into the coil by using water jet. Resistivity and magnetization measurements were done on small pieces cut from the samples to examine the properties of the samples and weld region. It was observed from the levitation force measurements 30 % Y211 + 0.1 % CeO2 added samples were had the highest repulsive force, while 40 % Y211 + 0.1 % CeO2 added samples were had the lowest. However, the critical current densities of the samples were had in the same order with the other samples whereas expect to lower. It is found that superconducting properties of the sample was cured with second thermal process. On the other hand, decreasing of the width of magnetization curves of these samples was higher than the other samples with the magnetic field. It was observed that superconducting transition gaps of the all samples were small in resistivity measurements at different fields. While the Y1-ek sample had the lowest transition gap, the Y3-b sample had the highest at 0 T magnetic field. It was determined that 40 % Y211 adding is high and an addition Y211 in the range 30-20 % is found to be suitable