Development of technology for a reliable fabrication of LRE-123 materials for levitation applications above 80 K

Abstract

Nanoscale secondary phase Gd 2BaCuO 5 “Gd-211” particles less than 60 nm in size, added to mixed ternary LREBa 2Cu 3O y [LRE = (Nd 0.33Eu 0.33Gd 0.33), (Sm 0.33Eu 0.33Gd 0.33), (Nd 0.33Sm 0.33Gd 0.33)] “NEG-123, SEG-123, NSG-123” oxide powders and melt-processed in Ar–1%pO 2 gas mixture, significantly improve electromagnetic performance at low magnetic fields. As confirmed by transmission electron microscopy and dynamic force microscopy, the nanoparticles in the LRE-123 matrix not only survive the melt-texturing process but, thanks to their contamination by Zr coming from ball milling process, these particles in majority transform into a new type of even smaller defects. Further improvement in flux pinning was reached when both 123 and 211 powders were thoroughly ball milled before the melt-growth process to the similar small size. As a result, J c values of 260 kA/cm 2 and 55 kA/cm 2 were observed in remnant state at 77 K and 90 K, respectively.