X-ray photoelectron spectroscopy analysis ofBi2Sr2Ca1−xYxCu2Oy

Experiments on x-ray photoelectron spectroscopy of ${\mathrm{Bi}}_2$ ${\mathrm{Sr}}_2$ ${\mathrm{Ca}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Y}}_{\mathit{x}}$ ${\mathrm{Cu}}_2$ ${\mathrm{O}}_{\mathit{y}}$ were performed to investigate the change of valence of each atom and the distribution of Y atoms on the cation sites. The core-level binding energies of Sr and Y increased with increasing Y content and that of Bi did not change. The average valence of Cu was above 2 for 0.0≤x≤0.5 and below 2 for 0.8≤x≤1.0. Y atoms were substituted for the cations between the adjacent Cu-O planes.