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

Abstract

Large-size, two-dimensional YBCO films such as 5-cm-∅ circles and 12 × 3 cm 2 rectangles were successfully prepared by a chemical solution-based coating-pyrolysis process on sapphire substrates with an evaporated-CeO 2 buffer layer. Two types of furnace systems were adopted in the final heat treatment depending on the sample dimensions. A 5-cm-∅ 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 12 × 3 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.