Indexed on: 17 Sep '14Published on: 17 Sep '14Published in: Journal of Superconductivity and Novel Magnetism
High-quality long REBCO-coated conductors have been successfully fabricated on flexible metal substrates by pulsed laser deposition (PLD). Although thinner REBCO films had a very high critical current density Jc of 5.0 × 10 6 A/cm 2 (at 77 K, in zero magnetic field), Jc of thick films decreased to less than 3.0 × 10 6 A/cm 2 as the thickness increased over 1 μm. In order to improve superconducting properties of REBCO thick films, microstructure and surface morphology of different thick REBCO films were systematically analyzed to understand the relationship between Jc and epitaxial growth process. X-ray diffraction (XRD) analysis showed that thick REBCO films still had pure c-axis orientation by Gd substitution and Y 2O3 doping. Scanning electron microscope (SEM) images showed thick REBCO films with high Jc had sub-micrometer size grains and narrow grain-boundaries. Our experimental results showed REBCO thick films with Ic of 780 A/cm could be obtained. Hundred meters long coated conductor tapes with 500 A/cm have been routinely fabricated. And now, the process optimization for kilometer long coated conductor tapes is underway.