Ce 3d XPS investigation of cerium oxides and mixed cerium oxide (Ce _<i>x</i> Ti _<i>y</i> O _<i>z</i> )

Abstract

Abstract This article presents an XPS study of Ce 3d emission spectra dominated by atomic multiplet effects in core level spectroscopy of rare earth compounds (Ce oxides). Core level spectroscopy has been used to study the electronic states of Ce 3d 5/2 and Ce 3d 3/2 levels in Ce 4+ and Ce 3+ states. The well‐resolved components of Ce 3d 5/2 and Ce 3d 3/2 spin‐orbit components, due to various final states (4f 0 , 4f 1 , 4f 2 configurations), were determined on 3d XPS spectra from commercial powders (CeO 2 , CePO 4 ). These results were used to study the 3d spin‐orbit component of mixed cerium‐titanium oxide. This compound was prepared by co‐melting commercial powders of CeO 2 and TiO 2 at 1800 K under air using a solar furnace with a flux density of 16 MW.m −2 at the focal point of the parabolic concentrator. The mixed oxide Ce 2 Ti 2 O 7 was produced and contained Ce(III) species which may be reactive with water to give back the initial metal oxides and generate hydrogen, a valuable product considered as a promising energy carrier in the future in replacement of oil. The 3d photoemission spectra revealed the presence of mixed components attributed to mainly Ce(III) and Ce(IV) species. Copyright © 2008 John Wiley &amp; Sons, Ltd.