Valence States of Lead and Bismuth Atoms in the High-Temperature Superconductor BaPb1-xBixO3

Abstract

X-ray photoelectron spectra of valence bands and core levels of BaPb0.8Bi0.2O3, PbO, PbO2, BaPbO3, BaBiO3, NaBiO3, and Bi2O3 were studied. Comparison of the electron binding energies of the Pb 4f7/2 or Bi 4f7/2 core levels for all the oxides studied showed that the high-temperature oxide superconductor BaPb0.8Bi0.2O3 contains simultaneously two different valence forms of lead atoms (PbIV and PbII) and two different valence forms of bismuth atoms (BiV and BiIII). Parameters of the X-ray photoelectron spectra of the valence bands do not contradict the conclusion on heterovalent states of lead and bismuth atoms in BaPb0.8Bi0.2O3.