Research Of Preparation Of High Quality La₂Zr₂O₇Buffer Layer By Metal Organic Decomposition Method

With excellent electrical properties, the2-generation high temperaturesuperconductor wires based on YBa₂Cu₃O_7-δ（YBCO） has a wide range of applicationsin many fields，especially in the electric power field. In the preparation of YBCO onflexible tapes it is necessary to add a buffer layer strcucture, serving as barrier to blockthe metal and oxygen atoms diffusion and as template layer to transfer the biaxialtexture of substrates.The buffer layer texture directly influence the performance ofsuperconductor. Therefore, the preparation of buffer layer is a key process forsuperconductor wires.Comparing with many buffer materials, La₂Zr₂O₇（LZO） film is currently of greatinterest because of its many distinctive advantages, i.e., small lattice mismatch withYBCO material, effectively blocking Ni and O atoms diffusion, structure stability,simple fabrication method and low-cost. In this article, LZO buffer film wassystematically investigated by metal organic decomposition （MOD） method on biaxiallytextured Ni-5at.%W tapes.First of all, in order to study the growth process, LZO film was deposited on Ni-Wsubstrates by MOD method, indicating a strong pure a-axis orientation when annealingat1100°C for60min. However, the out-of-plane and in-plane texture were not well,showing that the Δω and Δφ values were7°and6.2°, respectively. Therefore, morework was needed to further optimize the texture of the film.PVD-Y₂O₃seed layer was inserted to improve the MOD-LZO texture. The effectof different texture of PVD-seed on the microstructure of3-layer MOD-LZO film wasstudied in detail. The Δω, Δφ, and root-mean-square roughness（RMS） of typical3-layerLZO film were3.34°,4.59°and6.96nm, respectively, indicating a significantimprovement in the crystallographic texture comparing with LZO/Ni-W film.Meanwhile, double-sided MOD-LZO film was attempted to prompt the carry currentcapability of YBCO.In order to prepare cost-effective, high-quality LZO film by all-MOD method,MOD-seed layer was used to optimize the LZO crystallographic texture. The effect of fabrication parameters of different MOD-seed layer, i.e., precursor solutionconcentrations, annealing temperature and time, on LZO texture were studied in detail.The results showed that LZO film on MOD-CeO₂seed had the most excellent improvedtexture when MOD-seed annealing at800℃for30min, and the Δω and Δφ values of3-layer LZO film were5.09°and4.83°. Finally, YBCO films were sputtered on3-layerLZO/Ni-W, LZO/MOD-Y₂O₃/Ni-W and LZO/MOD-CeO₂/Ni-W buffer films and the Jcvalues were0.6MA/cm²,1.2MA/cm², and1.4MA/cm², respectively. In summary, theinsertion of MOD-seed layer achieved the preparation of high-quality LZO buffer filmby all-MOD method and improved the properties of the superconducting film.