| In the 2nd generation wire technology of high temperature superconducting coated conductors, highly conductive and nonmagnetic Cu substrate can improve the wire properties along with the conductive buffer layers, offering fully conductive wire architecture. This scheme requires two components, namely oxidation resistance for the Cu tape and conductive buffer layers.; The growth of epitaxial Cu2Mg as an oxidation barrier was investigated. Epitaxy of (004) Cu2Mg intermetallic phase was achieved on (002) Cu film. An in-plane ϕ-scan through the Cu2Mg (222) and the x-ray diffraction rocking curve for the (004) Cu2Mg peak indicates that the intermetallic phase is well oriented on (002) Cu surface.; The perovskite (La,Sr)TiO3 was investigated as a possible conducting oxide buffer layer for high temperature superconducting coated conductors. YBa2Cu3O7 was grown epitaxially on (La,Sr)TiO3 buffer layer on SrTiO3 substrate with excellent in-plane and out-of-plane alignment. The superconducting transition temperature (Tc) of YBa2Cu3O 7/(La,Sr)TiO3/SrTiO3 structure was 91 K and the critical current density (Jc) of this structure was 2.18x106 A/cm2 at 0 magnetic field. The resistivity results of a post annealed sample at YBa2Cu 3O7 deposition condition indicates that the (La,Sr)TiO 3 layer can be a candidate for the conductive buffer layer in the coated conductor applications. The epitaxial film growth of (La,Sr)TiO3 was examined on Ni-W metal alloy tape. The transition metal nitride such as TiN was deposited epitaxially on Ni-W tape by PLD and played an excellent role as a seed layer for (La,Sr)TiO3 film growth on Ni-W tape. The YBa2Cu3O7 film was deposited epitaxially on the (La,Sr)TiO3 buffer layer with the TiN seed layer on Ni-W tape. The YBa2Cu3O7 film grown on (La,Sr)TiO 3/TiN/Ni-W tape has Tc of 89 K and Jc of 0.42x106 A/cm2.; The epitaxial film growth of (La,Sr)TiO3 was examined on Cu tape as a possible conducting buffer layer for high temperature superconducting coated conductors. The noble metal, such as Ir, was deposited epitaxially on Cu tape by PLD for an oxygen diffusion barrier. The YBa2Cu 3O7 film was deposited epitaxially on the (La,Sr)TiO 3 and Ir buffer stack on Cu tape. The YBa2Cu3O 7 film grown on the (La,Sr)TiO3/Ir/Cu tape has a superconducting transition temperature of 90 K and a critical current density value of 1.0x10 6 A/cm2. This shows that (La,Sr)TiO3 is a possible candidate for the conductive buffer layer in the Cu based RABiTS applications. |
