Characterization of 50-mm-diameter Y123 films prepared by a coating-pyrolysis process using an infrared image furnace

Epitaxial YBa2Cu3O7-y (Y123) films were prepared on 50-mm-diameter LaAlO3 (LAO)(0 0 1), NdGaO3 (NGO) (1 1 0) and CeO2-buffered AI(2)O(3)(0 1 2) substrates by a chemical solution-based coating-pyrolysis process using a large-area infrared image furnace for high-temperature heat treatment. The furnace provides uniform temperature distribution over the film specimens and high irradiation power density that enables a high heating rate (similar to200 degreesC/min). An average inductive-J(c) (77 K) in excess of 2 MA/cm(2) was reproducibly obtained for 0.3-0.7-mum-thick c-axis-oriented Y123 films on LAO(0 0 1), of which the variation was fairly small all over the films. Microwave surface resistance of the film was 0.48 mOmega at 12 GHz and 70 K by the sapphire rod resonator method. Moreover, an average J(c) (77 K) = 0.5 MA/ cm(2) and T-c = 89 K were attained in a 0.3-mum-thick film on CeO2-buffered Al2O3(0 1 2). Despite being subjected to rapid thermal annealing, the Y123 film on NGO(1 1 0) was a-axis oriented and resulted in lower J(c) (77 K) = 0.15 MA/cm(2) and T-c= 84 K. (C) 2002 Elsevier Science B.V. All rights reserved.