Oxidation Behavior at the Ni–W and ${\rm CeO}_{2}$ Interface With and Without Pd Over Layer

The interface between the cube textured Ni-W substrate, both bare and Pd-buffered, and the CeO₂/YSZ buffer layer structure-required to growth YBCO coated conductors-samples have been subjected to different oxidizing conditions and have been investigated with different techniques: X-ray diffraction (XRD), X-ray absorption and Auger electron spectroscopy. Due to the Ni-Pd interdiffusion, the presence of a Pd over layer significantly modifies the substrate surface composition and the substrate oxidation mechanism. Depending on the Pd layer thickness, the formation of NiO can be completely prevented while the formation of ternary oxides and of W oxide is favored. Moreover, the Pd layer affects the extension of interface between the substrate and the CeO₂ layer and the portion of uncontaminated CeO₂.