Development of Textured Buffer Layer on Metal Tapes for Oxide Superconductors

High current carrying conductors for various commercial and military applications can be fabricated by using a coating of high-temperature superconductor such as Yttrium-Barium-Copper-Oxide (YBCO) on a suitable metallic tape. It has been shown, however,that YBCO films deposited directly on polycrystalline metal substrates exhibit poor superconducting properties at liquid nitrogen temperature. A textured buffer layer on metal substrates is needed for the growth of YBCO films with a high critical currentdensity. In Phase I, UES has demonstrated the feasibility of growing highly textured MgO films on polycrystalline substrates using inclined substrate deposition (ISD) technique. A multilayer architecture incorporating ISD MgO layer on metal substratesexhibited optimum properties of the overlaying YBCO films. In Phase II, UES proposes to further optimize the multilayer architecture and develop a pilot production process for coating long metal tapes. A reel-to-reel sputter deposition system at UES willbe equipped with an electron beam evaporation source for this scale-up. Argonne National Laboratory and State University of New York, Albany will provide support in YBCO depositions and characterizations of coated conductors.