Reel‐to‐Reel Continuous Chemical Solution Deposition of Epitaxial Gd 2 O 3 Buffer Layers on Biaxially Textured Metal Tapes for the Fabrication of YBa 2 Cu 3 O 7−δ Coated Conductors

• Published in: Journal of the American Ceramic Society Vol. 86; no. 2; pp. 257 - 265
• Main Authors: Aytug, Tolga, Paranthaman, Mariappan P., Kang, Byeongwon W., Beach, David B., Sathyamurthy, Srivatsan, Specht, Eliot D., Lee, Dominic F., Feenstra, Roeland, Goyal, Amit, Kroeger, Donald M., Leonard, Keith J., Martin, Patrick M., Christen, David K.
• Format: Journal Article
• Language: English
• Published: 01.02.2003
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1151-2916.2003.tb00009.x

A nonvacuum reel‐to‐reel dip‐coating system has been used to continuously fabricate epitaxial Gd 2 O 3 buffer layers on mechanically strengthened, biaxially textured Ni–(3 at.% W–1.7 at.% Fe), defined as Ni‐alloy, metal tapes. Because of its significance as a seed layer, optimum processing conditions (postannealing speed and temperature) of Gd 2 O 3 buffer layers have been studied. Highly textured films were obtained under reducing (96% Ar + 4% H 2 ) atmosphere at temperatures between 1100° and 1150°C; postannealing speed did not significantly affect the crystalline quality of the Gd 2 O 3 . Scanning electron microscopy revealed a continuous, dense, and crack‐free surface morphology for these dip‐coated buffers. The Gd 2 O 3 layer thickness led to pronounced differences in the growth characteristics of the subsequent YSZ and CeO 2 layers deposited by rf‐magnetron sputtering. Epitaxial YBCO films grown by pulsed laser deposition on the short prototype CeO 2 /YSZ/Gd 2 O 3 /Ni–(3 at.% W–1.7 at.% Fe) conductors yielded self‐field critical current densities ( J c ) as high as 1.2 × 10 6 A/cm 2 at 77 K. Pure Ni tapes were used to assess the viability of dip‐coated buffers for long length coated conductor fabrication. The YBCO films, grown on 80 cm long and 1 cm wide CeO 2 /YSZ/Gd 2 O 3 buffered Ni tapes by the industrially scalable ex situ BaF 2 precursor process, exhibited end‐to‐end self‐field J c values of 6.25 × 10 5 A/cm 2 at 77 K. These results demonstrate the reproducible epitaxy of solution‐derived seed layers on pure Ni and Ni‐alloy tapes as well as underscore the viability of solution approaches for the production of long length YBCO‐based coated conductors.