Long-length IBAD-MgO buffer layers for high performance RE-123 coated conductors by a large ion beam source

Abstract

In Fujikura, a large-scale ion-beam-assisted deposition (IBAD) system with a large ion source has been employed to fabricate biaxially textured MgO films. The large-scale IBAD system has multiple deposition lanes where substrate tapes move, and therefore we have to optimize experimental conditions at each lane. We selected an appropriate deposition area and, finally, we successfully fabricated a 1km-length IBAD-MgO film at a production rate of 1km/h. We also studied pulsed-laser-deposited (PLD) CeO2 films directly on the IBAD-MgO films in spite of a large lattice mismatch between CeO2 and MgO. From transmission electron microscope (TEM) observations at an interface between MgO and CeO2 films, it is revealed that there is domain-matching-epitaxy relationship between MgO and CeO2 films. We also fabricated thin (1.0μm) and thick (3.7μm) PLD – GdBa2Cu3O7−x (GdBCO) film on the long-length CeO2/MgO substrate (over 150m). Critical currents (Ic) and current density (Jc) were over 300 A and 3MA/cm2 respectively for the thin GdBCO film and were about 645 A and 1.7MA/cm2 for the thick GdBCO film at 77K in self-field.