Abstract Body

High T_c superconducting (HTS) bulk LREBa₂Cu₃O_y (LRE: Nd, Sm, Eu, Gd) "LRE-123" superconductors, with critical temperatures (T_c) above the boiling point of liquid nitrogen (77.3 K) have numerous technological and industrial applications. Typically, these bulk superconductors are fabricated employing top-seeded melt growth (TSMG) or infiltration growth (TSIG) processes. Recent experiments have shown that TSIG overcomes the limitations of TSMG_[1]. Among the HTS bulk LRE-123 superconductors, ternary LRE-Ba₂Cu₃O_y superconductors, such as (Nd,Eu,Gd)Ba₂Cu₃O_y and (Sm,Eu,Gd)Ba₂Cu₃O_y are renowned for their superior superconducting performance. These superconductors exhibit levitation at liquid oxygen temperature (90.2 K) and show irreversibility at 15 T at 77 K, H // c-axis _[2,3]. However, fabricating these ternary LRE-Ba₂Cu₃O_y compounds requires specific oxygen-controlled environments due to RE/Ba substitutions, which can degrade superconducting performance when fabricated in air.  In this work, we successfully fabricated ternary (Sm,Eu,Gd)Ba₂Cu₃O_y bulk in the air using the TISG process, achieving enhanced superconducting performance. Initially, we used various liquid sources, such as REBa₂Cu₃O_y + Ba₃Cu₅O₈ (1:1) (RE= Sm, Gd, Y and Er), to fabricate the bulk. The bulk obtained using YBa₂Cu₃O_y+ Ba₃Cu₅O₈ exhibited a sharp transition width (∆T_c) of 3.88 K, representing a 52.5% improvement compared to the bulk obtained from ErBa₂Cu₃O_y+ Ba₃Cu₅O₈. To further enhance the transition width, we systematically enriched the (Sm,Eu,Gd)₂BaCuO₅ precursor powder with various weight percentages of BaO₂ to control the RE/Ba substitutions. With optimized BaO₂ in the secondary phase, we achieved a T_{(c, onset)} of > 94 K and ∆T_c < 1 K. The enhanced bulk sample showed a 71.24 % improvement over the reference sample. These results facilitate the fabrication of high-performance ternary (Sm,Eu,Gd)Ba₂Cu₃O_y bulk superconductors in air, broadening their applications in various industrial and technological fields.

References

[1] Agarwal, A. G., & Miryala, M. (2024). Ceram. Int., 50 (17), 31559-66
[2] Muralidhar, M. (2002). Phys. Rev. Lett., 89, 237011-1
[3] Muralidhar, M., et al. (2003). Appl. Phys. Lett., 83 (24), 5005-5007

Acknowledgment

Akash Garg Agarwal acknowledges financial support from SIT for the doctoral program.

Keywords: Top-seeded infiltration growth; Ternary Bulk LRE-123; RE/Ba substitution; Critical temperature.