Fabrication of high-Jc YBCO films by the TFA-MOD process using YBCO powder as precursor

YBCO thin films were prepared on LaAlO₃ (100) single-crystal substrates using the metal-organic deposition of trifluoroacetates (TFA-MOD). Unlike the normal TFA-MOD process, TFA-based solutions were prepared dissolving YBCO powder into the trifluoroacetic acid solvent. The solutions were coated on the substrates by spin coating, fired at the temperature up to 400°C in 4.2% humid and oxygen atmosphere, fired again at the temperature region of 725-850°C for 2 h in 4.2% humidity and 1000 ppm oxygen partial pressure, and finally oxygenated at 450°C for 1 h. Similar to the normal TFA-MOD process, both microstructure and superconducting properties of YBCO films were highly sensitive to the firing temperature. Optimally processed YBCO films of ∼250 nm thickness exhibited T_C,zero of 90 K and J_C of 2.9 MA/cm² at 77 K in a self-field. The present results clearly evidence that our cost-effective modified TFA-MOD process is applicable to the fabrication of YBCO coated conductors.