Development of Solution Buffer Layers for RABiTS Based YBCO Coated Conductors

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 CeO
₂
cap/YSZ barrier/Y
₂
O
₃
seed on Ni-5%W metal tape. In the present work, we have identified CeO
₂
buffer layer as a potential replacement for Y
₂
O
₃
seeds. Using a metal-organic deposition (MOD) process, we have grown smooth, crack-free, epitaxial thin films of 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 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 CeO
₂
samples. We have also demonstrated the growth of YSZ barrier layers on pure CeO
₂
seeds using sputtering. Both sputtered CeO
₂
cap layers and MOD-YBCO films were grown epitaxially on these YSZ-buffered MOD-CeO
₂
/Ni-5W substrates. High critical currents per unit width, I
_c
of 264 A/cm (critical current density, J
_c
of 3.3 MA/cm
²
) at 77 K and 0.01 T was achieved for 0.8 μm thick MOD-YBCO films grown on MOD-CeO
₂
seeds. These results indicate that 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.