Assessment of Chemical Solution Synthesis and Properties of Gd2Zr2O7 Thin Films as Buffer Layers for Second-Generation High-Temperature Superconductor Wires

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.