Abstract

The precise characterization of REBCO thin films is an ongoing point of research interest as improved characterization methods help to accelerate the optimization of REBCO Coated Conductor manufacturing conditions. Keeping that in mind, fast and reliable measurement methods like X-ray diffraction (XRD) are needed to determine critical parameters such as the crystalline structure of produced thin films.
The REBCO crystal structure is hugely influenced by the oxygen deficiency δ. Depending on δ either an orthorhombic or tetragonal unit cell is prevalent. With ω/2θ scans in the coplanar plane the lattice parameters a,b,c can be determined for thin film samples. Thus, by investigating the relationship between the lattice parameters a,b,c and the oxygen deficiency δ, XRD could be used to reliably characterize oxygenation processes in the production of REBCO thin films.
In this work, we observe the oxygen out-diffusion in different gas atmospheres and determine the lattice parameters a,b,c on accumulative heat-treated samples. The c lattice parameter showed a continuous change while oxygen was diffusing out of the crystal lattice. A relationship between c and δ, which follows Vegard's rule could be established.