An XPS investigation of (La2O3)1-x (CeO2)2x (ZrO2)2 compounds†

(La2O3)1-x (CeO2)2x (ZrO2)2 mixed oxides (LCZ) where 0 ≤ x ≤ 1 were synthesised from commercial La2O3, CeO2 and ZrO2 powders and co-melted in a 2-kW solar furnace. These samples were re-oxidised in air at temperatures that ranged from 900 K to 1100 K. The microstructures of the LC, LCZ and CZ oxides were investigated by XPS and XRD. Core-level spectroscopy (XPS) has been used to study electronic states (III) and (IV) of the Ce 3 d5/2 and Ce 3 d3/2 levels. The resolved components of the Ce 3 d3/2,5/2 features were identified. The rate of Ce3+ and Ce4+ states were calculated for different values of x (0.1–1). The nature of the chemical bonds of Ce and O were determined from the Ce 3 d3/2,5/2 and O 1 s photoelectron peaks, respectively.The XRD study revealed the presence of solid solutions (LCZ and CZ). The presence of crystalline phases (pyrochlore and fluorite-like structures) depends on the value of x. A decrease in the lattice parameter was observed with increasing x. La atoms were substituted by Ce atoms in a solid solution, and the oxygen vacancies were filled. The amount of fluorite-like phase increases with an increasing amount of Ce atoms. Copyright © 2012 John Wiley & Sons, Ltd.