| dc.description |
In an effort to develop alternative single buffer layer architectures for YBCO (YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-y</sub>) coated conductors, we have studied RE<sub>2</sub>O<sub>3</sub> (RE = Y, and rare earths) as candidate materials. High-quality Y<sub>2</sub>O<sub>3</sub>, Gd<sub>2</sub>O<sub>3</sub> and Yb<sub>2</sub>O<sub>3</sub> buffer layers were grown epitaxially on biaxially textured Ni (100) substrates using reactive electron beam evaporation. Using thermodynamic considerations for the formation of metal oxides, we employed both reducing atmospheres and water vapour to oxidize the film in situ to form stoichiometric RE<sub>2</sub>O<sub>3</sub>. We have also prevented NiO formation at the substrate-film interface during this process. Detailed x-ray studies have shown that the Y<sub>2</sub>O<sub>3</sub>, Gd<sub>2</sub>O<sub>3</sub> and Yb<sub>2</sub>O<sub>3</sub> films were grown with a single epitaxial orientation. The lattice mismatch between YBCO and Gd<sub>2</sub>O<sub>3</sub> was small as compared with that of YBCO with other rare earth oxides. SEM micrographs indicated that ~0.5 µm thick Y<sub>2</sub>O<sub>3</sub> films on rolled-Ni substrates were dense, continuous and crack free. A high J<sub>c</sub> of 1.8 × 10<sup>6</sup> A cm<sup>-2</sup> at 77 K and self-field was obtained on YBCO films grown on alternative buffer layers with a layer sequence of YBCO/Yb<sub>2</sub>O<sub>3</sub> (sputtered)/Y<sub>2</sub>O<sub>3</sub> (e-beam)/Ni. |
