Special variation of infiltration-growth processed bulk YBCO fabricated using new liquid source: Ba₃Cu₅O₈ (1:1.3) and YbBa₂Cu₃O_y

Utilization of novel materials, particularly high-T_c (critical temperature) superconductors, is essential to pursue the United Nations’ Sustainable Goals, as well as to meet the increasing worldwide demand for clean and carbon-free electric power technologies. Superconducting magnets are beneficial in several real-life applications including transportation, energy production, magnetic resonance imaging (MRI), and drug delivery systems. To achieve high performance, one must develop uniform, large-grain, infiltration-growth (IG) processed bulk YBa₂Cu₃O_y (Y-123) super-magnets. In this study, we report the magnetic and microstructural properties of a large-grain, top-seeded, IG-processed Y-123 pellet, which is 20 mm in diameter and 6 mm in height; the pellet is produced utilizing liquid Yb-123+Ba₃Cu₅O₈ as the liquid source. All the samples cut from the top of the bulk exhibit a sharp superconducting transition (approximately 1 K wide) with the onset T_c of approximately 90 K. However, in the samples cut from the bottom surface, the onset T_c values slightly decreased to between 88 and 90 K, although still exhibiting a sharp superconducting transition. The top and bottom samples exhibited the highest remnant value of J_c (critical current density) at 77 K H//c-axis of 50 and 55 kA/cm², respectively. The remnant J_c and irreversibility field values significantly fluctuated, being fairly low in some bottom samples. Scanning electron microscopy identified nanometer size Y-211 (Y₂BaCuO₅) secondary-phase particles dispersed in the Y-123 matrix. Energy-dispersive spectroscopy clarified that the decreased both T_c and J_c for the bottom samples were attributed to liquid phase dispersion within the Y-123 phase.