Improving sol-gel Yba₂Cu₃O_7−δ film morphology using high-boiling-point solvents

The effect of high-boiling-point solvent addition on the morphology of low-p(O₂) processed, sol-gel YBa₂Cu₃O_7−δ (YBCO) films is discussed. Proper selection and addition of a high-boiling-point solvent prevents film roughening during precursor pyrolysis, while permitting at least a tenfold reduction in pyrolysis time compared to standard film processing in air or O₂. Use of such solvents appears to increase film plasticity, avoiding elastic compressive stress related buckling. High-quality YBCO films on 〈100〉 LaAlO₃ with a critical current density (J_c) ∼ 3–4 MA/cm² at 77 K, are routinely crystallized with this new sol-gel process. Diethanolamine-based, sol-gel YBCO films deposited on sol-gel SrTiO₃-buffered 〈100〉 Ni have J_c(77 K) > 1 MA/cm², demonstrating a route toward all-sol-gel superconducting wires.