[WBP1] Conductor Processing & Evaluation

[WBP1-21] Effect of the Ba/RE ratio on the critical current in BaZrO₃ nanoparticle–doped Y-Gd-Ba-Cu-O–coated conductor formed by trifluoroacetate-based metal–organic deposition

*Michio Sato¹, Takuma Oyamada¹, Kei Shiohara¹, Yuji Aoki¹, Kazuhisa Adachi¹, Rin Takajom², Riichiro Tashiro², Masayoshi Inoue², Koichi Nakaoka³, Teruo Izumi³ (1. SWCC Corporation (Japan), 2. Fukuoka Institute of Technology (Japan), 3. National Institute of Advanced Industrial Science and Technology (Japan))

Keywords:

REBCO Coated Conductors,TFA-MOD

The urgent need to substantially reduce carbon dioxide (CO₂) emissions in the wake of global heating has become a critical issue worldwide. Against this backdrop, decarbonization strategies have become essential also in the aviation industry. In this situation, the development of electric aircraft is crucial. Superconducting propulsion systems are the leading candidate for developing electric aircraft. The motor, generator, and cable of such systems should be employed long and high-performance superconducting wires/tapes.Recently, we fabricated long BaZrO₃-doped Y_0.77Gd_0.23Ba₂Cu₃O_y (YGdBCO + BZO)–coated conductors (CCs) through trifluoroacetate-based metal–organic deposition (TFA-MOD) using a reel-to-reel system furnace. By adopting intermediate heating treatment and ultra-thin once-coating (UTOC) techniques [1, 2]. These 100-m-class CCs had a high uniform I_c distribution in the self-field at 77 K [3, 4]. However, the developed CCs had high amounts of second-phase contents, such as CuO, Y₂O₃, and Y₂Cu₂O₅, which prevented the current from entering the superconducting layer and proved detrimental to high I_c. Controlling the Ba/RE ratios in the starting solution is a key factor in overcoming this problem and improving the in-field I_c properties.In this work, we fabricated YGdBCO + BZO CCs with various Ba/RE ratios in the starting solution to suppress the second phase and improve the in-field I_c properties. The CCs with Ba/RE = 1.8 have a self-field I_c of 471 A/cm-width at 77 K, which is 1.25 times that of the CCs with a standard Ba/RE value of 1.5, which is the suitable ration for the previous process without UTOC [5]. Moreover, pre-annealing resistivity measurements (via a two-terminal method) showed that CCs with Ba/RE = 1.8 had an average resistivity of 0.38 W×mm, which is an order magnitude lower than that of the CCs with standard Ba/RE = 1.5. Hence, we anticipate that controlling the Ba/RE ratios in the starting solution is an effective way to suppress the second phase and improve the in-field I_c properties in YGdBCO + BZO CCs.In this presentation, we will report on the in-field I_c properties and microstructure of the YGdBCO + BZO CCs fabricated with various Ba/RE ratios for the UTOC-MOD process.
AcknowledgementsThis study is based on findings obtained from a project, which was subsidized by the New Energy and Industrial Technology Development Organization (NEDO).
Reference[1] K. Nakaoka et al., J. Phys.: Conf. Ser., vol. 1293, 2019.[2] T. Izumi et al., IEEE Trans. Appl. Supercond., vol. 27, 2017.[3] M. Sato et al., IEEE Trans. Appl. Supercond., vol. 34, 2024.[4] M. Sato et al., IEEE Trans. Appl. Supercond., vol. 35, 2025.[5] K. Nakaoka et al., Physica C 463–465, 519–522, 2007.