Preparation and characterization of solution deposition planarized Y₂O₃–Al₂O₃ compound seed layer for coated conductors

In this work, we have successfully fabricated the second-generation YBa₂Cu₃O₇ (YBCO)-coated conductors on the solution deposition planarization (SDP) yttrium oxide and aluminum oxide (Y₂O₃-Al₂O₃, YAlO) templates. Distinguishing from commercially available coated conductors, the SDP-YAlO process employs chemical solution deposition to fabricate multi-layer amorphous oxides on polycrystalline metal substrates, presenting a cost-effective alternative to replace sputtering-Al₂O₃, sputtering-Y₂O₃, and electrochemical polishing processes. The detailed SDP-YAlO fabrication process has been studied systematically. The YAlO seed layer exhibits smooth and flat surface morphology with an optimal root mean square roughness (RMS) of 1.6 nm over a 5 μm x 5 μm area, indicative of a smooth surface. Furthermore, the YBCO functional layer was deposited on ion beam-assisted deposition (IBAD) MgO buffer layers, utilizing both SDP-Y₂O₃ and SDP-YAlO as seed layers. The critical current (J_c) uniformity of YBCO films on SDP-YAlO is much better that those on SDP-Y₂O₃, indicating the potential of SDP-YAlO as a promising seed layer for YBCO-coated conductors.