Investigation of thick PLD-GdBCO andZrO2 doped GdBCO coated conductors with high critical current onPLD-CeO2 capped IBAD-GZO substrate tapes

Abstract

In order to increase the critical current,Ic, we havefabricated thick GdBa2Cu3O7−δ (GdBCO) coated conductors (CCs) by the pulsed laser deposition (PLD) method onPLD-CeO2/ion-beam assisteddeposition (IBAD)-Gd2Zr2O7 (GZO)/hastelloy metal substrate tapes. The highest critical current value was522 A cm−1 for athickness of 3.6 µm in self-field at 77 K. It was found that a low volume fraction ofa-axis orientated grains was obtained in the thick GdBCO CCs, compared toYBa2Cu3O7−δ (YBCO) CCs. Consequently, the GdBCO CCs showed higher critical current density(Jc) than YBCO CCs in all thicknesses from 0.2 to3.6 µm. Furthermore, we have succeeded in improvingIc in a magnetic field by the introduction of artificial pinning centres using a 5 mol%ZrO2 doped GdBCO target. In the measurement of theIc dependence on themagnetic field angle, θ,Ic was much improved,especially at 0°, i.e., with the magnetic field parallel to thec-axis. TheIc value at3 T was 59.5 A cm−1 at0° and it showeda minimum of 42.3 A cm−1 at 82° for 2.28 µm thick CC. The minimum value in the angular dependence ofIc at 3 T was about five times higher than that of YBCO CC and two times higher than thatof pure GdBCO CC.