X-ray photoelectron spectra and composition of YBa$_2$Cu$_3$O$_{7-\delta}$ films prepared by laser ablation

Y3$d$, Ba3$d_{5/2}$, Cu2$p_{3/2}$, and O1$s$ X-ray photoelectron spectra of thick (600 nm) superconducting YBa$_2$Cu$_3$O$_{7-\delta}$ films deposited on textured Ni–W substrates with Y$_2$O$_3$+ZrO$_2$, CeO$_2$ and CeO$_2$ buffer layers have been studied. It has been established that, after the mechanical removal of surface layers with a diamond scraper (and as the analyzed region of the film approaches the interface), a decrease in the oxygen content leads to a decrease of the orthophase fraction and an increase of the tetraphase and Cu$^+$ ion fractions. This is caused by the presence of elastic stresses in the superconducting film due to the lattice misfit between the phases making up a composite sample. These stresses prevent oxygen diffusion involved in oxidizing annealing. The spectra of the superconducting film have not revealed signals generated by elements of the substrate and buffer layers.