3146 zyxwvutsrqponmlkj IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 11, NO. 1, MARCH 2001 Fabrication of Long Lengths of YBCO Coated Conductors using a Continuous Reel-to-Reel Dip-Coating Unit M. Paranthaman, T.G. Chirayil, zyxwvuts S. Sathyamurthy, D.B. Beach, A. Goyal, F.A. List, D.F. Lee, X. Cui, S.W. Lu, B. Kang, E.D. Specht, P.M. Martin, D.M. Kroeger, R. Feenstra, C. Cantoni, and D.K. Christen Abstract-A low-cost, non-vacuum, solution precursor route has been developed to produce epitaxial GdtO3 and E11203 buffer layers and YBazCu3074 (YBCO) superconductors on biaxially textured metal substrates. On sol-gel E11203 seed layers with sputtered YSZ and CeOz top layers, YBCO film with a J, of over 1 MA/cm2 at 77 K was obtained. On all solution buffer layers (CeOfiutOfli), YBCO film with a J, of 200,000 A/cmZat 77 K was grown using pulsed laser deposition (PLD). Meter lengths of epitaxial and crack-free Gd203 buffer layers were fabricated on cube textured NI-W (3 at. zyxwvut YO) substrates for the first time. High quality YBCO films were deposited on Rolling-Assisted Biaxially Textured Substrates (RABiTS) using a trifluoroacetate (TFA) precursor approach. The precursors were either spin-coated or dip-coated and decomposed in a newly developed fast 3-hour burn-out step followed by post-annealing. In a stationary burn-out route, we have produced 40 cm long crack-free YBCO TFA precursors on RABiTS. On short segments, YBCO films with a Jc of over 500,000 A/cm2 at 77 K were grown on all zyxwvuts PLD buffered-Ni substrates (CeOz/YSZ/CeOz/Ni). Index Terms- Solution precursors, RE203 buffer layers, YBCO coated conductors, textured metal substrates I. INTRODUCTION For the promise of high-temperature superconductivity to be realized, practical processes are needed to manufacture useful lengths of high-temperature superconducting (mS) wires. The goal is to produce robust, economical, and scaleable processes for making wire that can carry sufficient current at liquid nitrogen temperatures. The second- generation YBCO coated conductors are the potential candidates. Also, YBCO coated conductors have good superconducting properties in significant magnetic fields at the liquid nitrogen temperatures. Three methods have been developed for producing long lengths of YBCO coated conductors. The first method is the “Ion Beam Assisted Deposition (IBAD), which was developed by Iijima et al. [l] and later significantly improved at Los Alamos [2]. In the IBAD technique, YSZ (Yttria-stabilized zirconia) or MgO buffer templates with a biaxial cube texture were produced on polycrystalline nickel alloy substrates using a well- collimated secondary gun directed towards the substrate at a certain angle to sputter off non-favorable orientations during the buffer layer deposition. This is followed by Pulsed Laser Deposition (PLD) to grow high quality YBCO layers. The second method is the Rolling-Assisted Biaxially Textured Substrates (RABiTS) process, developed at Oak Ridge [3,4]. In this process the biaxial texture templates were produced in the starting nickel or nickel alloy substrates using mechanical deformation of the metal rods over zy 95 % followed by annealing. The buffer layers and Yl3CO superconductors were then grown epitaxially on biaxially textured nickel tapes or sheets. The third method is the Inclined Substrate Deposition (ISD), which was developed in Japan zyxwv [5], and further pursued in Europe and United States. In this approach, the biaxially textured YSZ or MgO buffer layer templates were produced by keeping the starting polycrystalline nickel alloy substrates at certain angle with respect to the on-axis flux of the buffers. The YBCO layers were then deposited by PLD. Chemical solution epitaxy has emerged as a viable, non- vacuum process for fabricating epitaxial buffer layers and YBCO superconductors [6-121. The roll-textured nickel substrates are the ideal starting templates for this process. The major advantages of solution processes are: The coating of metal-organic precursor solution is done at room at high temperatures to obtain highly crystalline phases. The control of precursor stoichiometry or doping is both easy precise. n i S is completely a non-vacuum, high volume deposition process. The material utilization is ahnost 100 YO and the substrates Manuscript received September 18,2000. This work was supported by the U.S. Department of Energy, Division of Materials Sciences, Office of Science, office of Power Technologies-SuperconductivityProgram, Office of Energy Efficiency and Renewable Energy. The research was performed at the Oak Ridge National Laboratory, managed by UT.-Battelle, LLC for the USDOE under contract DE-AC05400R22725. M. Paranthaman. T.G. Chiravil. S. Sathvamurthv. and D.B. Beach are with Chemical & Analytical Scienffis Division: Oak Ridge National Laboratory, Oak Ridge, TN 37831-6100 (telephone: 865-574-5045, email: could be coated on both sides. In order to scaleup the paranthamanm@oml.gov) Martin, and D.M. KrOeger are with Metals & Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 3783 1 Oak Ridge National Laboratory, Oak Ridge, TN 3783 1 solution process, a reel-to-reel dip-coating process was A. Goyal, F.A. List, D.F. Lee, X. Cui, S.W. LU, B. brig, E.D. Specht, P.M. developed. The dip-coated precursors could be post- annealed in a batch or in a continuous process. We have R. Feen&a, C, Cantoni, and D.K. Christen are with Solid State Division, an alkoxide route to produce oxide buffer layers on roll-textured nickel substrates [ 8- 1 11. 1051-8223/01$10,00 zyxwvutsr 0 2001 IEEE Authorized licensed use limited to: Oak Ridge National Laboratory. 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