Levitation Force Density on Different Thicknesses of YBa_2Cu_3O_(7-x) Bulk Superconductor Fabricated by FQMG Process

摘要

A precursor YBCO in the stoichiometric ratio of 1:2:3 was prepared by the flame-quench-melt-growth (FQMG) method. Both the superconducting and nonsuperconducting regions were decided by measuring the magnetic levitation force per unit volume as a function of thickness of the superconducting sample. It was determined that superconducting forming ratio depends on where it forms in the sample, and thus a region near the top surface of the sample contains more superconducting forming ratio than the other regions. The levitation force density measured at different thicknesses of the sample ranging from 6.54 to 1.58 mm firstly increased and then separately reached a saturation point (maximum value) for both repulsive and attractive levitation force density. It was found that the maximum values of the repulsive and attractive levitation forces were respectively 125 mN/cm~3 and - 23 mN/cm~3. The considerably improved F_L - z performance in FQMG sample can be translated to large-scale Y123 blocks intended for real superconducting levitation applications.