Zr:CeO₂ Buffer by CSD on Ni-W Substrate for Low-Cost Fe(Se,Te) Coated Conductor

Although Fe(Se,Te) film shows limited superconducting properties compared to REBCO in terms of critical temperature and critical current density, it represents a potential low-cost alternative to REBCO-based coated conductor applications at low temperature and high field condition. In fact, due to the low deposition temperature and absence of oxygen, materials constraints are less strict and Fe(Se,Te) coated conductor can be realized using a very simplified architecture. A further process simplification is the use of cube-textured substrate combined with a single buffer layer by chemical solution deposition (CSD), which may provide a cheap, vacuum-free route for oriented template fabrication. Zr-doped CeO2/Ni-W templates were realized by CSD and successfully tested with epitaxial Fe(Se,Te) film growth by pulsed laser deposition showing good superconducting properties. Further, a detailed analysis before and after buffer layer deposition using optical, atomic, and scanning electron microscopy, electron backscattered diffraction and Raman and X-ray photoelectron spectroscopy was carried out to relate Zr-doped CeO2 film quality to Ni-W microstructure, morphology, and composition. Results show that 30-nm-thick Zr-doped CeO2 film is effective to prevent Ni diffusion. Further, buffer-layer quality is mainly dependent on the characteristics of individual Ni-W grains.