Fabrication of Thick REBCO–Coated Conductors with High Performance on Metal Tapes by Pulsed Laser Deposition Process

Abstract

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 J c of 5.0 × 10 6 A/cm 2 (at 77 K, in zero magnetic field), J c 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 J c 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 2 O 3 doping. Scanning electron microscope (SEM) images showed thick REBCO films with high J c had sub-micrometer size grains and narrow grain-boundaries. Our experimental results showed REBCO thick films with I c 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.