Optimization of the Dy Content in Single Crystalline GdBCO Bulk Superconductors Fabricated in Air Via Top-Seeded Infiltration Growth Process

Single-crystalline bulk GdBa₂Cu₃O_7−δ (GdBCO) superconductors were fabricated with top-seeded infiltration-growth technique (TSIG) in air by adding the different amounts of Dy₂BaCuO₅ (Dy-211) particles (5, 10, 15, 20, 25, 30, 35, and 40 wt%). All the samples show superconducting critical temperature at ∼93 K with sharp transition irrespective of the chemical composition. X-ray diffraction measurements confirmed that all the samples were single domain with high alignment. Microstructural studies through scanning electron microscopy showed that TSIG-processed GdBCO samples contained 211 phase particles of two different sizes, i.e., ∼2–4 and ∼10 μ m. The addition of Dy-211 phase particles led to a significant enhancement of critical current density (J_c) at 77 K. GdBCO superconductor with the addition of 20 wt% of Dy-211 showed the highest J_c of 45.5 kA/cm ² at 77 K and self field.