Regensburg 2007 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 12: Symposium “Coated HTS Conductors”

TT 12.7: Talk

Tuesday, March 27, 2007, 11:30–11:45, H20

Temperature series to study the biaxial texturing of La₂Zr₂O₇ buffer layers on nickel-tungsten substrates — •Leopoldo Molina¹, Sebastian Engel², Bernhard Holzapfel², and Oliver Eibl¹ — ¹Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, D-72076, Tübingen, Germany — ²IFW Dresden, P.O.Box 270116, D-01171 Dresden, Germany

La₂Zr₂O₇(LZO) buffer layers are currently of great interest for YBa₂Cu₃O_7−x(YBCO) coated conductor technology. The mechanism of biaxial texturing of the film was investigated by varying the annealing temperature. The LZO buffer layers were prepared by chemical solution deposition (CSD) and annealed at temperatures ranging from 600^∘C to 1000^∘C in order to study the growth, biaxial-texture and microstructure of the LZO thin films. Nanovoids of 10-50 nm were found to be a typical feature of the buffer layers. Samples were investigated by transmission electron microscopy (TEM) and x-ray diffraction (XRD). Diffraction contrast imaging and convergent beam electron diffraction (CBED) techniques were used to investigate the microstructure of the films in plan-view and cross-section. XRD measurements showed that LZO grain growth starts at T>800^∘C. The average Ni grain size of the biaxially textured nickel tungsten substrates is 40µm and the grain size of the LZO buffer layers is 100-200 nm. Thus, even though the films are highly biaxially textured, no epitaxial growth occurs.