Investigation of multi-deposition for high Ic YBCO coated conductors prepared by PLD on self-epitaxial CeO2 buffers

For fabrication of YBa₂Cu₃O_7-x (YBCO) coated conductors with high J_c, we have investigated pulsed laser deposition (PLD) of YBCO on the "self-epitaxial" PLD-CeO₂ layer on an ion beam assisted deposition (IBAD)-Gd₂Zr₂O₇ (GZO) buffered Hastelloy tape. A multiple coating of YBCO layer (multi-deposition) improved the uniformity in transport properties. In order to increase I_c, we investigated the proper depositing conditions for a thick YBCO layers. It was found that raising the referential deposition temperature, in accordance with the YBCO layer growths, is effective to suppress a-axis oriented grains and increase I_c. A high I_c as high as 293 A was obtained in a 10 cm long conductor. Furthermore, we succeeded in the deposition of a 0.8 m long YBCO coated conductor with the end-to-end I_c of 225 A and J_c of 1.13 MA/cm². The latter coated conductor also exhibited good uniformity, whose standard deviation of I_c distribution is 2.2%. These results demonstrated that the multi-deposition applying heater temperature increase corresponding to the YBCO thickness is effective in a preparation of high I_c and uniform YBCO coated conductors.