Fabrication and Characteristic of -123 Coated Conductors

We have developed HoBa₂Cu₃O_7-x (Ho-123) coated conductors on flexible metal tape substrates. Oxide buffer layers such as YSZ and CeO₂ have been deposited on textured Ni-alloy tapes. A basic technique of the formation of buffer layer was investigated, and hetero-epitaxial buffer layer of CeO₂ /YSZ/CeO₂ showed excellent in-plane alignment with the delta phi value in the range of 5 to 7 degrees. Surface roughness (Ra) of 3rd buffer layer was several nm and the surface was almost flat with few particles. Ho-123 deposition was conducted on the buffer layers by PLD method. Sample less than 0.2 mum in thickness of superconducting layer showed Jc (77.3 K, self field) over 4 MA/cm². Sample with 1.3 mum in thickness of superconducting layer showed Jc (77.3 K, self field) was 1.8MA/cm² near 2MA/cm² and Ic (77.3 K, self field) was 231 A/cm-width. SEM photograph of Ho-123 layer revealed relatively smooth film morphology with some particles. This demonstrated fine epitaxial Ho-123 growth on CeO₂/YSZ/CeO₂ textured Ni-alloy tape. Furthermore, Jc-B characteristics at 4.2 K under the high magnetic field up to 30 T were evaluated. Ic (4.2 K, 30 T) was over 2,000 A/cm-width when the external magnetic field was applied parallel to the tape surface