Incoherent BaMO₃ (M=Zr, Hf, Sn etc) nanoparticles (NPs) have been shown to have great success in improving superconducting performance[1] in materials such as REBa₂Cu₃O_y (REBCO) superconducting films and iron-based superconducting films [2,3]. To be effective, the BHO NP size has to be tuned, and the density needs to be higher with little degradation of the matrix crystallinity, carrier density and critical temperature (T_c) for greater enhancement.

We show how an economically viable method, namely trifluoroacetate metal organic deposition (TFA-MOD), can be tuned to obtain both small size and high density of NPs while maintaining the crystallinity of the REBCO matrix. We get significant enhancement of the in-field critical current density (J_c) over a broad temperature and field-angle range by changing the NP material and by modulating the precursor chemistry with the result of constraining the NPs spatially. The enhancements are seen not only in in-field J_c but also in self-field J_c. The self-field J_c of our nanocomposite REBCO CC reaches over 30% of the depairing current density (J_d) over broad ranges of temperature. Detailed microstructural and superconducting properties for nanocomposite REBCO CCs will be presented.

Acknowledgements: This presentation is based on results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO). A part of this work was supported by JSPS KAKENHI (18KK0414 and 20H02184), Promotion and Mutual Aid Corporation for private Schools of Japan (Science Research Promotion Fund).

Reference: [1] M. Miura et al., NPG Asia Materials 9 (2017) e447.  [2] M. Miura et al., Nature Commun. 4 (2013) 2499. [3] M. Miura et al., Supercond. Sci. Technol. 32 (2019) 064005.

Keywords: Critical Current, Flux Pinning, TFA-MOD, Coated Conductor, Nanoparticles