Fabrication of high J_c YBa₂Cu₃O_7-δ coated conductors using sol-gel buffer layers on nickel and nickel alloy substrates

Sol-gel processing of La₂Zr₂O₇ (LZO) buffer layers on biaxially textured Ni-3 at.% W alloy substrates using a continuous reel-to-reel dip-coating unit has been studied. The epitaxial LZO films obtained have a strong cube texture and uniform microstructure. The effect of increasing the annealing speed on the texture, microstructure and the carbon content retained in the film were studied. On top of the LZO films, epitaxial layers of Yttria Stabilized Zirconia (YSZ) and Ceria (CeO₂) were deposited using rf sputtering, and YBa₂Cu₃O_x (YBCO) films were then deposited using Pulsed Laser Deposition (PLD). A critical current density (J_c) of 1.9 MA/cm² at 77K and self-field and 0.34 MA/cm² at 77K and 0.5T have been obtained on these films. These values are comparable to those obtained on YBCO films deposited on all-vacuum deposited buffer layers, and are the highest ever obtained using solution seed layers. The use of all-solution buffers for coated conductor processing has also been explored. A critical current density of 1.1 MA/cm² at 77 K and self-field was obtained on YBCO films grown be PLD on LZO buffered nickel substrates.