Development of Solution Buffer Layers for RABiTS Based YBCO Coated Conductors

摘要

The main objective of this research is to find a suitable alternate solution based seed layer for the standard RABiTS three-layer architecture of physical vapor deposited $hbox{CeO}_{2}$ cap/YSZ barrier/$hbox{Y}_{2}hbox{O}_{3}$ seed on Ni-5%W metal tape. In the present work, we have identified $hbox{CeO}_{2}$ buffer layer as a potential replacement for $hbox{Y}_{2}hbox{O}_{3}$ seeds. Using a metal-organic deposition (MOD) process, we have grown smooth, crack-free, epitaxial thin films of $hbox{CeO}_{2}$ (pure and Zr, Cu and Gd-doped) directly on biaxially textured Ni-5W substrates in short lengths. Detailed XRD studies indicate that a single epitaxial $hbox{CeO}_{2}$ phase with slightly improved out-of-plane texture compared to the texture of the underlying Ni-W substrates can be achieved in pure, undoped $hbox{CeO}_{2}$ samples. We have also demonstrated the growth of YSZ barrier layers on pure $hbox{CeO}_{2}$ seeds using sputtering. Both sputtered $hbox{CeO}_{2}$ cap layers and MOD-YBCO films were grown epitaxially on these YSZ-buffered MOD- $hbox{CeO}_{2}$/Ni-5W substrates. High critical currents per unit width, $I_{rm c}$ of 264 A/cm (critical current density, $J_{c}$ of 3.3 $hbox{MA/cm}^{2}$) at 77 K and 0.01 T was achieved for 0.8 $mu{hbox {m}}$ thick MOD-YBCO films grown on MOD- $hbox{CeO}_{2}$ seeds. These results indicate that $hbox{CeO}_{2}$ films can be grown directly on Ni-5W substrates and still support high performance YBCO coated conductors. This work holds promise for a route for producing low-cost buffer architecture for RABiTS based YBCO coated conductors.