IBAD-MgO buffer layers for coated conductors in the large-scale system

For practical applications of high-temperature superconductor tape, the high production rate of tapes is needed to reduce its cost. Recently, the long-length coated conductor with high performance has been fabricated by an ion beam assisted deposition/pulsed laser deposition (IBAD/PLD) method in Fujikura. In IBAD process, we adopted IBAD-Gd2Zr2O7 (GZO) film. The process speed of IBAD-GZO film was increased up to 5 m/h using a polished metal substrate tape. To fabricate biaxially-textured buffer layers at a higher rate, we have started to develop another structures such as (a) IBAD-GZO/IBAD-MgO (3-fold symmetry) and (b) IBAD-MgO (4-fold symmetry). In the case (a), we fabricated GdBCO/CeO2/IBAD-GZO/IBAD-MgO tape and the critical current was I-c = 550 A/cm (2.46 MA/cm(2)) and throughput of IBAD processes were 20 m/h. In the case (b), IBAD-MgO short samples with Delta phi of, 9 degrees-11 degrees were obtained at 500 m/h. The 500 m/h (10 mm width) is extremely high rate in [BAD process in the world. As long-length IBAD layer 10 m, 50 m and 100 in IBAD-MgO films were fabricated at the speed of 100 m/h. After CeO2 deposition, in-plane textures of these samples were Delta phi of 3.7 degrees-3.7 degrees, 4.1 degrees-4.9 degrees and 4.2 degrees-4.8 degrees. Using some of these buffer layers, we have obtained GdBCO film with I-c = 400 A/cm (2 MA/cm(2), 10 m) and I-c = 550 A/cm (2.7 MA/cm(2), short sample), (C) 2009 Elsevier B.V. All rights reserved.