Epitaxial growth of gradient Ce1−xZrxO2 buffer layer for YBa2Cu3O7−δ coated conductors

A Ce1−xZrxO2 (CZO) buffer layer architecture with gradient change of Zr-doped concentration along the thickness direction of CZO films was fabricated on rolling assisted biaxially textured NiW metallic substrate by sol–gel method. With the change of Zr-doped concentration, the lattice parameters of CZO of each layer also show a gradient variation. It can not only effectively reduce interfacial stress between the buffer layer and the metallic substrate, but also improve the surface quality of the CZO film. In this work, an epitaxial growth relationship and dense microstructure are discerned in the gradient CZO film, as determined by the comprehensive analysis of X-ray diffraction and scanning electron microscopy. YBCO superconductor films have been deposited on the gradient CZO buffer layers to evaluate the quality of such a gradient buffer layer. TEM measurements reveal that NiW/CZO/YBCO coated conductor (CC) with excellent epitaxial growth relationship is achieved. The superconducting transition temperature of the sample is 90 K and the critical current density Jc reaches 1.9 MA/cm2.