Investigation of thick PLD-GdBCO and ZrO2 doped GdBCO coated conductors with high critical current on PLD-CeO2 capped IBAD-GZO substrate tapes

In order to increase the critical current, I-c, we have fabricated thick GdBa2Cu3O7-delta ( 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 mu 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-delta ( YBCO) CCs. Consequently, the GdBCO CCs showed higher critical current density ( J(c)) than YBCO CCs in all thicknesses from 0.2 to 3.6 mu 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, theta , I-c was much improved, especially at 0 degrees., 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 degrees. and it showed a minimum of 42.3 A cm(-1) at 82 degrees for 2.28 mu 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.