XPS STUDIES ON CERIUM, ZIRCONIUM AND YTTRIUM VALENCE STATES IN PLASMA-SPRAYED COATINGS

X‐ray photoelectron spectroscopy (XPS) is used for investigating the valence state of the chemical elements present in 25.5 wt.% CeO2−2.5 Y2O3−72 ZrO2 plasma‐sprayed coatings as a function of the deposition temperature. Unlike the other chemical elements, cerium changes its valence state during and after the spraying process. The analysis of Ce 3d binding energies and satellite structures shows that CeO2 after spraying is either partially reduced to Ce(III) at low deposition temperature, or remains essentially unchanged at high deposition temperature. In both cases, the presence of ZrO2−x suboxides is found, which does not depend apparently on the cooling rate. Copyright © 1990 John Wiley & Sons Ltd.