XPS and XANES study onPb2Sr2YCu3O8+δ and PbBaSr(YCa)Cu3O7+δ

Abstract The charge distribution inPb 2 Sr 2 YCu 3 O 8+δ and PbBaSrY 1− x Ca x Cu 3 O 7+δ has been studied by X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES). The Cu 2p core-level and the Pb M 3 XANES show that the valences of Cu and Pb in the blocking layers are + 1 and + 2, respectively, for the oxides synthesized in a reducing atmosphere (δ = 0). The valences of Cu and Pb increase after oxidation by annealing in O 2 gas. On the other hand, the substitution of Ca for Y ( x = 0.2) hardly changes the valences of Cu and Pb. The core-levels of Ba, Sr and Y are not changed in the binding energy by the oxidation, but are shifted to the lower-binding-energy side by the substitution. These results will be discussed in terms of charge distributions in the crystal structures before and after the oxidation and substitution.