Solution deposition approach to high Jc coated conductor fabrication

Great strides have been made in YBCO coated conductor fabrication using the RABiTS approach in the past few years and critical current densities (J_c) of over 3 MA/cm² on 10 meter long tapes have been achieved. Solution deposition for buffer layer processing has the potential to reduce the process complexity and make the conductor fabrication more cost-effective. In our work, we have demonstrated that several of the standard buffer layers can be replaced by sol-gel processed lanthanum zirconium oxide (LZO) layer. A J_c of about 2 MA/cm² has been demonstrated on LZO films for pulsed laser deposited YBCO and J_c up to 1.5 MA/cm² have been demonstrated for MOD-YBCO using a sputtered CeO₂ cap layer on the sol-gel LZO films. Solution processed buffer layers have been found to have rapid growth kinetics which could potentially mean high rate processing of these buffer layers. Using simulated ex-situ YBCO annealing studies, it has been determined that the performance of 80-120 nm thick LZO films is comparable to the standard 3-layer vapor deposited CeO₂/YSZ/Y₂O₃ buffer stack. Using a 120 nm thick LZO layers on NiW substrates, in collaboration with American Superconductor Corp., all-solution coated conductors with the stacking sequence MOD-YBCO/Solution CeO₂/Solution LZO/NiW, critical currents of up to 140 A/cm has been measured. Such high critical currents on an all-solution conductor offers promise for cost-effective scale-up of coated conductor processing.