Microstructure and macroscopic superconducting properties of GdBa 2 Cu 3 O y bulk superconductors with different heights

Abstract Bulk single‐grain GdBCO superconductors with a nominal composition of 1 mol GdBa₂Cu₃O₇ ‐δ + 1/2 mol Gd₂BaCuO₅ + 20 wt% Ag₂O + 0.5 wt% CeO₂, and with varying heights, were grown using a top‐seeded melt growth process. The diameter of the prepared GdBCO samples was 17.5 mm, with heights ranging from 5 to 11 mm. Additionally, the tallest GdBCO sample was cut incrementally to match the heights of the grown samples. The macroscopic superconducting properties of the samples were measured at 77.3 K on both the top and bottom surfaces. It was observed that the decrease in the maximum trapped magnetic field, as well as the decrease in levitation force with decreasing sample height, differed between the top and bottom surfaces. The influence of macrostructural and microstructural features, such as the distribution of residual melt, and the volume fraction and size of Gd211 particles in growth sectors, on the trends of this decrease is analyzed.