Nonstoichiometry behavior of La1-xSrxCoO3-delta series perovskite oxides wa
s studied by XPS and cyclic voltammetry. The results indicate that the chem
ical states of La and Sr in the oxides are barely influenced by their relat
ive content. Substitution of Sr for La results in the valence state change
of some cobalt ions from Co3+ to Co4+ and the increase of the lattice oxyge
n vacancies. (C) 2000 Elsevier Science S.A. All rights reserved.