Fabrication of long lengths of epitaxial buffer layers on biaxially textured nickel substrates using a continuous reel-to-reel dip-coating unit

A low-cost, nonvacuum, solution precursor route has been developed to produce epitaxial oxide buffer layers of Eu₂O₃ or La₂Zr₂O₇ on biaxially textured Ni (100) tapes. A reel-to-reel continuous dip-coating unit consisting of a constant-tension tape transport system attached to a controlled atmosphere furnace was fabricated. Nickel tapes were pulled through a 2-methoxyethanol solution of europium methoxyethoxide/acetate or lanthanum zirconium methoxyethoxide. The double-sided dip-coated tapes were then annealed in a preheated furnace at 1000°-1100 °C with a high flow rate of Ar/H₂ (4%) gas. The dip-coated buffers were dense, continuous, crack-free, and epitaxial with a single cube texture. A critical current (J_c) of >1 MA/cm² at 77 K and self-field was obtained for YBa₂Cu₃O_7-δ (YBCO) films with a layer sequence of YBCO (ex situ BaF₂ process)/CeO₂ (sputtered)/YSZ (sputtered)/Eu₂O₃ (dip-coated)/nickel. We have produced 1-2 m lengths of epitaxial buffer layers on textured nickel substrates using a nonvacuum process for the first time.