Investigation of thick PLD-GdBCO and ZrO₂doped GdBCO coated conductors with high critical current on PLD-CeO₂capped IBAD-GZO substrate tapes

Abstract

In order to increase the critical current, Ic, we have fabricated thick GdBa2Cu3O7?? (GdBCO) coated conductors (CCs) by the pulsed laser deposition (PLD) method on PLD-CeO2/ion-beam assisted deposition (IBAD)-Gd2Zr2O7 (GZO)/hastelloy metal substrate tapes. The highest critical current value was 522?A?cm?1 for a thickness of 3.6??m in self-field at 77?K. It was found that a low volume fraction of a-axis orientated grains was obtained in the thick GdBCO CCs, compared to YBa2Cu3O7?? (YBCO) CCs. Consequently, the GdBCO CCs showed higher critical current density (Jc) than YBCO CCs in all thicknesses from 0.2 to 3.6??m. Furthermore, we have succeeded in improving Ic in a magnetic field by the introduction of artificial pinning centres using a 5?mol% ZrO2 doped GdBCO target. In the measurement of the Ic dependence on the magnetic field angle, ?, Ic was much improved, especially at 0?, i.e., with the magnetic field parallel to the c-axis. The Ic value at 3?T was 59.5?A?cm?1 at 0? and it showed a minimum of 42.3?A?cm?1 at 82? for 2.28??m thick CC. The minimum value in the angular dependence of Ic at 3?T was about five times higher than that of YBCO CC and two times higher than that of pure GdBCO CC.