Composite ${\rm Y}_{2}{\rm O}_{3}-{\rm Al}_{2}{\rm O}_{3}$ as Diffusion Barrier/Nucleation Layer for HTS Coated Conductors Based on IBAD MgO

A composite layer has been successfully implemented in high temperature superconducting (HTS) coated conductors (CCs) based on ion beam assisted deposition (IBAD) MgO technology. This layer serves a dual function: a nucleation layer for the growth of high quality biaxially aligned MgO and a diffusion barrier to inhibit interdiffusion between the Ni-alloy substrate and the superconductor. The composition of the composite Y₂O₃-Al₂O₃ influences the texture and superconducting properties of YBCO films grown on STO buffered MgO/Y₂O₃-Al₂O₃/Ni-alloy. Our experimental results demonstrate that the superconducting properties of YBCO grown on STO buffered MgO/Y₂O₃-Al₂O₃/Ni-alloy are comparable with those of YBCO on standard architecture. The use of a single composite Y₂O₃-Al₂O₃ layer instead of individual layers of Y₂O₃ and Al₂O₃ for the fabrication of HTS CCs based on IBAD MgO provides advantages such as simplified architecture and potentially reduced cost due to the reduced number of fabrication steps.