Synthesis and Optimization of Fluorine-Free Y & Cu Precursor Solution for MOD Processing of YBCO Coated Conductor

MOD solutions for YBCO coated conductors were synthesized with fluorine-free Y & Cu precursor. The fluorine content in the precursor solution was significantly reduced and a fast calcination profile was realized. A crack-free & thick precursor film was successfully obtained just after less than 2 hours of calcination in wet O₂ atmosphere. Optimization of the precursor solution with Sm addition enables further improvement of thickness and uniformity of precursor films. The calcinated precursor film was successfully converted to dense and uniform YBCO film after annealing in wet Ar/O₂ atmosphere. The measured critical current value was about 273 A/cm-w (J_c ~ 3.8 MA/cm²), and well-developed microstructure was confirmed. Also discussed are recent developments in the reel-to-reel processing using the precursor solution with low fluorine-content. It was shown that employing fluorine-free Y & Cu precursor solution enabled uniform and fast processing of YBCO coated conductors.