High-J{sub}c YBCO coatings on reel-to-reel dip-coated Gd{sub}2O{sub}3 seed buffer layers epitaxially fabricated on biaxially textured Ni and Ni-(3atW-1.7atFe)alloy tapes

摘要

A low-cost, non-vacuum reel-to reel dip-coating system has been used to continuously fabricate epitaxial Gd{sub}2O{sub}3 buffer layers on mechanically strengthened, biaxially textured Ni(3at.%W- 1.7at%Fe), defined as Ni-alloy, metal tapes. X-ray diffraction analysis of the seed Gd{sub}2O{sub}3 layers indicated that well textured films can be obtained at processing temperatures (T{sub}p) between 1100 and 1175°C. Processing speed did not significantly affect the crystalline quality of the Gd{sub}2O{sub}3. Scanning electron microscopy revealed a continuous, dense and crack-free surface morphology for these dip-coated buffers. The Gd{sub}2O{sub}3 layer thickness led to remarkable differences in the growth characteristics of the subsequent YSZ and CeO{sub}2 layers deposited by rf-magnetron sputtering. Epitaxial YBCO films grown by pulsed laser deposition on the short prototype CeO{sub}2/YSZ/Gd{sub}2O{sub}3/Ni-(3at%W- 1.7at%Fe) conductors yielded self-field critical current densities (J{sub}c) as high as 1.2×10{sup}6 A/cm{sup}2 at 77 K. Pure Ni tapes were used to asses 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{sub}2/YSZ/Gd{sub}2O{sub}3 buffered Ni tapes by the industrially scalable ex-situ BaF{sub}2 precursor process, exhibited end-to-end self-field J{sub}c of 6.25×10{sup}5 A/cm{sup}2 at 77 K.