Magneto-Optical Characterization of (Nd_(0.33)Eu_(0.33)Gd_(0.33))Ba_2Cu_3O_y Bulk Superconductors With Different Gd-211 Content

摘要

We have investigated the ternary (Nd_(0.33)Eu_(0.33)Gd_(0.33))Ba_2Cu_3O_y (NEG-123) bulk superconductors with different amounts of Gd_2BaCuO_5 (Gd-211) second phase by using magneto-optical (M-O) imaging technique. An external magnetic field was applied parallel to the c-axis of the sample at various temperatures. The observed flux pattern images reflect the J_c-B characteristics of rectangular samples in perpendicular magnetic field. The M-O results are compared with DC magnetic measurements. The results show that fine dispersion of Gd-211 is effective in improving the pinning performance.