Top-seeded infiltration growth of (Y, Gd)Ba₂Cu₃Oy bulk superconductors with high critical current densities

We employed the top-seeded infiltration-growth (IG) process for the fabrication of bulk (Y, Gd)Ba₂Cu₃O_y (YG-123) superconductors by varying the composition of (Y, Gd)₂BaCuO₅ (YG-211) and compared with bulk YBa₂Cu₃O_y (Y-123) superconductors grown under similar conditions. IG-processed YG-123 exhibited J_c (77 K) of 4.78 × 10⁴ A cm^-2 in zero field, which was higher than the value of 3.71 × 10⁴ A cm^-2 for Y-123. The superconducting transition temperature (T_c) of YG-123 increased with increasing Gd content. However, there was spatial variation in the superconducting properties of IG-processed YG-123 samples due to the inhomogeneous distribution of YG-211. J_c values of YG-123 decreased when increasing the distance from the seed both along the a and c-axis directions. The scaling studies of the pinning behavior for YG-123 showed that non-superconducting YG-211 particles act as effective pinning centers, supported by the fact that δT_c type pinning is active in the system.