Raman Study of CeO 2 Texture as a Buffer Layer in the CeO 2 /La 2 Zr 2 O 7 /Ni Architecture for Coated Conductors

Abstract

The CeO₂/La₂Zr₂O₇/Ni piled-up structure is a very promising architecture for YBa₂Cu₃O₇ (YBCO) coated conductors. We have grown YBCO/CeO₂/LZO/Ni epitaxial structures by metalorganic decomposition (MOD) and metalorganic chemical vapor deposition (MOCVD) methods. The crystallographic quality of the CeO₂ layer is not well determined by conventional X-ray diffraction (XRD) due to the superposition of LZO and CeO₂ reflections. An alternative simple Raman spectroscopy analysis of the crystalline quality of the CeO₂ films is proposed. The F_2g Raman mode of CeO₂ can be quantified either by using two polarization configurations (crossed or parallel) or at two different rotation angles around the normal axis (0° and 45°) to obtain information about the sample texture. The sample texture can be determined via a quality factor (referred to as the Raman intensity ratio, RIR) consisting of calculating the ratio of the integrated intensity of the CeO₂ F_2g mode at 0° and 45° in parallel polarization. This factor correlates with superconducting performance and the technique can be used as an on-line nondestructive characterization method.