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High-TC Superconducting Oxide Films Produced from Solution Precursors
Published online by Cambridge University Press: 28 February 2011
Abstract
Superconducting films of Ba2RECu3O7−x were prepared from aqueous and aqueous-alcoholic mixed solutions of barium, rare earth (RE), and copper nitrates. The solutions were sprayed onto heated (100) orientated MgO, ZrO2 —9%Y2O3 and SrTiO3 substrates to form a dehydrated nitrate precursor; subsequent thermal treatment yielded the superconducting 2:1:3 compound. Earlier magnetic film studies with aqueous-alcoholic mixed solutions of rare-earth iron garnet precursors showed that alcohol improves the spreading and drying of solutions on substrates. Here, however, alcohol significantly lowers the solubility of Ba(NO3)2. Some compositions tend to phase segregate during film preparation. A key objective of this study was to understand reaction paths of the precursors in order to optimize the furnace annealing schedule. Film and substrate reactions complicate the process, especially for SrTiO3, which otherwise has a good lattice match with films. Analytical methods used were Knudsen effusion mass spectrometry, thermogravimetric analysis, x-ray diffraction, secondary ion mass spectroscopy, electron microscopy and temperature-dependent resistivity. The best samples showed a Tc of 95K and had zero resistivity below 89K. Advantages of this process include: simplicity of equipment, short deposition time; ease of making composition adjustments; and possible deposition on complex shapes.
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- Copyright © Materials Research Society 1988
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