Metal\nPropionate Solutions for High-Throughput Liquid-Assisted\nManufacturing of Superconducting REBa<sub>2</sub>Cu<sub>3</sub>O<sub>7‑δ</sub> (RE = Y, Gd, Sm, and Yb) Films

The cost-effective\nsynthesis of a series of metal propionate powders\n(copper, yttrium, barium, samarium, gadolinium, and ytterbium) is\ndeveloped through single chemical reactions resulting in five novel\ncrystalline forms. These complexes are valuable precursors for the\npreparation of epitaxial REBa<sub>2</sub>Cu<sub>3</sub>O<sub>7‑δ</sub> (REBCO) superconducting films (here, RE = Y, Sm, Gd, and Yb) through\nthe innovative transient liquid-assisted growth (TLAG) process based\non chemical solution deposition (CSD). TLAG-CSD shows impressive results\nwith YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7‑δ</sub> (YBCO),\nobtaining critical current densities of 2.6 MA/cm<sup>2</sup> (77\nK) on 500 nm films at unprecedented growth rates (50–2000 nm/s),\nboosting unprecedented high-throughput industrial production. With\na cardinal concern on designing the pyrolysis toward optimal nanocrystalline\nfilms for TLAG, an analysis of the thermal behavior of the synthesized\nprecursors is essential. Decomposition pathways for each metal propionate\nare established, and compatibility with TLAG-CSD is corroborated.\nMetal–organic solutions for these REBCO systems are successfully\nprepared, and their rheological properties and thermal behavior are\nanalyzed. This work demonstrates homogeneous nanocrystalline films\nthrough propionate-based REBCO precursor solutions, including several\nrare-earth ions, which display exemplary chemical and microstructural\ncharacteristics crucial for TLAG, and provides a base for a wide variety\nof CSD-based functional oxides.