Enhancing the superconducting properties of bulk (Sm,Eu,Gd)Ba2Cu3O7−δ: Impact of BaO2 and Ag2O addition via infiltration growth process in air

Abstract

The air fabrication of bulk LREBa2Cu3O7−δ [where LRE can be Nd, Sm, Eu, Gd, or combinations such as (Y,Gd), (Y,Er), (Sm,Eu,Gd), (Nd,Eu,Gd), and (Nd,Sm,Gd)] holds the potential to revolutionize the cost-effective production of high-temperature superconductors. This method enables batch processing on an industrial scale, opening up a range of applications across various fields with enhanced superconducting performance. In this study, we fabricated large single-domain (Sm,Eu,Gd)Ba2Cu3O7−δ using the top-seeded infiltration growth process in air. To suppress the RE/Ba substitutions, BaO2 was added in the secondary (Sm,Eu,Gd)2BaCuO5 (SEG-211) phase with various BaO2 weight percentages. The optimized sample achieved an onset critical temperature Tc(onset) of 94.57 K and a transition width of ΔTc < 1 K, representing a 71% improvement in ΔTc over the reference sample. Furthermore, the self-field critical current density Jc of the BaO2-optimized sample was 33.55 kA/cm2 at 77 K and 62.26 kA/cm2 at 65 K, H//c-axis. The addition of Ag2O to the BaO2-optimized sample yielded an onset critical temperature of Tc(onset) > 93 K and a transition width of ΔTc < 1.5 K. Significant improvement in high-field critical current density was observed in the Ag2O-added sample, with a Jc value of 18.14 kA/cm2 at 77 K and 1 T, and 50.54 kA/cm2 at 65 K and 3 T, H//c-axis. These results indicate that ternary (Sm,Eu,Gd)Ba2Cu3O7−δ can be produced in air using the IG process with optimal BaO2 and Ag2O, which is crucial for batch production in air.