2-D large-size YBCO films on sapphire for FCL prepared by coating-pyrolysis process

Large-size, two-dimensional YBCO films such as 5-cm-diameter circles and 12 x 3 cm(2) rectangles were successfully prepared by a chemical solution-based coating-pyrolysis process on sapphire substrates with an evaporated-CeO2 buffer layer. Two types of furnace systems were adopted in the final heat treatment depending on the sample dimensions. A 5-cm-diameter YBCO film annealed in an infrared image furnace showed an average inductive-J(c) value of 1.3 MA/cm(2) at 77 K. While, a 12x3 cm(2) rectangular film annealed in a large-diameter tube furnace demonstrated much more uniform inductive-J(c) distribution, i.e., 85% of the observations fall within +/-20% of the average although the J(c) value was approximately 0.4 MA/cm(2) at 77 K. (C) 2003 Elsevier B.V. All rights reserved.