Development of Low Aspect Ratio Coated Conductor

ReBa₂Cu₃O_7-x (ReBCO, Re = Y or rare earth) coated conductors are currently available as ribbon-shaped conductors. The high aspect ratio of such conductors is often regarded as a limitation for many electrotechnical applications due to the anisotropy of the electrical and mechanical properties and high ac losses. In this view, a method for the development of cube-textured, low aspect ratio wire substrate for ReBCO coated conductor is presented. The method is derived from the conventional cold-rolling and recrystallization process and modified to obtain a cube-textured wire with low aspect ratio rectangular cross section. To show the feasibility of the method, pure copper was used as raw material. Cube-textured copper substrate with a square cross section and a thickness around 0.5 mm was realized by longitudinally cutting a heavily cold-rolled thick tape. All 4 sides of the wire show a strong cube texture development. Cube texture development is comparable with the one obtained in standard tapes, with a fraction of cube-oriented area above 95% and a full width at half maximum of (002) ω-scan ranging from 6.5° to 7.5°. The quality of the obtained surfaces was tested through the epitaxial growth of MgO/Pd bilayer. Preliminary results indicate that all 4 sides of the wire are equally available for epitaxial film growth and lead to a comparable film quality.