Systematic x-ray photoelectron spectroscopic study of La1-xSrx-based perovskite-type oxides

X-ray photoelectron spectroscopy is used to analyse systematically a group of La1-xSrx-based mixed-metal perovskite-type oxides of interest in the development of oxygen separation membranes. Angleand temperature-resolved studies reveal compositional variations that correlate with the segregation of various elements during annealing. The complex 0 1s, Sr 3d(5/2) and La 3d(5/2) spectra could be curve-fitted systematically with two La 3d(5/2), three Sr 3d(5/2) and five 0 1s contributions, respectively, using fixed binding energies and full widths at half-maximum. The trends are discussed and assignments are made on the basis of peak intensity and composition variations noted during the angle- and temperature-resolved studies, literature data and nearest-neighbor electronegativities. In all cases, elements present at the outermost surface revealed higher binding energies than their bulk-bound counterparts. Copyright (C) 2002 John Wiley Sons, Ltd.