Chemical solution processing of Gd2Zr2O7 (GZO) thin films via sol-gel and metalorganic decomposition (MOD) precursor routes have been studied on textured Ni-based tape substrates. Even though films processed by both techniques showed similar property characteristics, the MOD-derived samples developed a high degree of texture alignment at significantly lower temperatures. Both precursor chemistries resulted in exceptionally dense, pore-free, and smooth microstructures, reflected in the cross-sectional and plan-view high-resolution scanning and transmission electron microscopy studies. On the MOD GZO buffered Ni–3at.% W (Ni–W) substrates with additional CeO2/YSZ sputtered over layers, a 0.8-μm-thick YBa2Cu3O7−δ (YBCO) film, grown by an ex situ metalorganic trifluoroacetate precursor method, yielded critical current, Ic (77 K, self-field), of 100 A/cm width. Furthermore, using pulsed-laser deposited YBCO films, a zero-field superconducting critical current density, Jc (77 K), of 1 × 106 A/cm2 was demonstrated on an all-solution, simplified CeO2(MOD)/GZO(MOD)/Ni–W architecture. The present study establishes GZO buffers as a candidate material for low-cost, all-solution coated conductor fabrication.

Metalorganic deposition (MOD) is an attractive process for low-cost, high-rate deposition of YBa2Cu3O7– (YBCO) films on continuous lengths of biaxially textured metallic templates for second-generation (2G) high-temperature superconductor (HTS) wires.MOD of YBCO films involves four steps:precursor synthesis, coating, decomposition, and reaction.The final films must meet stringent requirements, including high critical current, uniformity across the width and along the length of the textured substrate, and excellent mechanical properties.Achieving these properties has required the development of a metalorganic precursor that produces an intermediate BaF2-based film, which in turn is converted to a high-quality YBCO film.Understanding and controlling the deposition of the metalorganic precursor and its conversion to YBCO are critical to reproducibly manufacturing uniform, high-performance, HTS wires required for commercial applications.This article reviews the issues that must be addressed in the use of MOD for low-cost YBCO film fabrication and summarizes the performance of 2G HTS wires prepared by this manufacturing process.

Epitaxial lanthanum zirconate (LZO) buffer layers have been grown by sol-gel processing on Ni–W substrates. We report on the application of these oxide films as seed and barrier layers in coated conductor fabrication as potentially simpler, lower cost coated-conductor architecture. The LZO films, about 80–100-nm thick, were found to have dense, crack-free surfaces with high surface crystallinity. Using 0.2-μm YBCO deposited by pulsed laser deposition, a critical current density of 2 MA/cm2 has been demonstrated on the LZO films (YBCO/LZO/Ni–W). Using 0.8-μm YBCO deposited using metal organic decomposition, a critical current density of 1.7 MA/cm2 and a critical current of 135 A/cm have been demonstrated on the LZO barrier layer with a sputtered CeO2 cap layer (YBCO/CeO2/LZO/Ni–W). These results offer promise to replace several of the vacuum-deposited layers in the typical coated conductor architecture (YBCO/CeO2/YSZ/Y2O3/Ni/Ni-W).