Microstructure of Candidate Conductive Buffer and Superconducting Layers in a Coated Conductor Using {100} <001> Textured Cu Tape

To develop a low-cost coated conductor, a new wire architecture using conductive buffer layers and a metal tape with high conductivity has been proposed. Nb-doped SrTiO
₃
(Nb-STO) was chosen as the conductive buffer layer. A high JC of 2.5 MA/cm
²
at 77 K under a self-magnetic field was demonstrated using a Nb-STO buffer layer and a cube-textured Cu and stainless-steel laminate tape as a metal tape with high conductivity. Considering the industrial production of wires, it is preferable to have many suitable materials. Thus, Nb-doped TiO
₂
(Nb-TiO
₂
) was examined as a new conductive buffer layer. However, it was found to be difficult to grow a well biaxially aligned YBCO layer on a single Nb-TiO
₂
buffer. Therefore, in this paper, buffer layers combining both Nb-STO and Nb-TiO
₂
were prepared and an YBCO layer was deposited on this buffer layer by PLD with the purpose of realizing a superior conductivity characteristic to that of the single Nb-STO buffer layer. It was found that the combined buffer layer has potential use as a conductive buffer layer. However, the process must be optimized to increase the benefit of adding Nb-TiO
₂
to Nb-STO.