Melt processing and superconducting properties of single-domain GdBa2Cu3Oy, (Sm0.5Gd0.5)Ba2Cu3Oy and (Sm0.33Eu0.33Gd0.33)Ba2Cu3Oy superconductors fabricated in air

Single-domains of GdBa2Cu3Oy, (Sm0.5Gd0.5)Ba2Cu3Oy and (Sm0.33Eu0.33Gd0.33)Ba2Cu3Oy with and without BaCuO2-δ doping were successfully prepared under the ambient atmosphere via a two-step cooling method. At 77 K, all samples show a well-developed secondary peak effect. The combination of two-step cooling method and BaCuO2-δ addition is very effective to suppress the LRE-Ba substitution and hence improve superconducting properties. The Gd-Ba-Cu-O samples exhibit very high Jc values, which are comparable to those of the oxygen-controlled melt-growth (OCMG) Gd-Ba-Cu-O samples