Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 12: Symposium “Coated HTS Conductors”
TT 12.8: Vortrag
Dienstag, 27. März 2007, 12:00–12:15, H20
The pyrolysis of YBa2Cu3O7−δ thin films produced by metal-organic deposition using trifluoroacetic acid-based precursors — •Thomas Thersleff1, Sebastian Engel1, Martina Falter1, Brigitte Schlobach1, Kerstin Knoth1, Ludwig Schultz1,2, and Bernhard Holzapfel1 — 1Leibniz IFW-Dresden, Postfach 270116, 01171 Dresden, Germany — 2Dresden University of Technology, Department of Physics, D-01062 Dresden, Germany
To assist with the optimization of the TFA-MOD process for YBa2Cu3O7−δ coated conductor development, this work examines the pyrolysis stage - in which organic constituents are burned off - on both single crystal as well as buffered nickel substrates. Samples were dip-coated into precursor solutions prepared using metal acetates as well as YBa2Cu3O7−δ powder dissolved in trifluoroacetic acid and placed in a flowing gas furnace with a humid O2 atmosphere. While firing, individual samples were quenched at various temperatures, effectively freezing the pyrolysis development. These samples were then analyzed for phase formation using grazing incidence x-ray diffraction; surface morphology using AFM; decomposition reactions using TGA, DTA, and exhaust gas characterization; and stoichiometry using EDX. Additionally, cross-sectional cuts were made in the pyrolyzed layers with a FIB, facilitating a detailed discussion of the layer morphology. Results indicate that significant layer shrinkage occurs between 200 and 250 ∘C and reveal a large surface tension. BaF2 crystallizes above 270 ∘C while CuO forms above 200 ∘C. FIB results suggest that HF gas evolves above 200 ∘C but is trapped within the layer until 270 ∘C.