title: Local structure and nanoscale homogeneity of CeO2-ZrO2: differences and similarities to parent oxides revealed by luminescence with temporal and spectral resolution.
abstract: Although homogeneity at the atomic level of CeO2-ZrO2 with a Ce/Zr atomic ratio close to unity is considered to be one of the main causes for the increased total oxygen storage capacity (OSC), the characterization approaches of homogeneity remain a major challenge. We propose a simple, yet effective method, to assess both structural and compositional homogeneity of CeO2-ZrO2 by using Eu(3+) luminescence measured with time and dual spectral resolution (emission and excitation). For Eu(3+)-CeO2-ZrO2 calcined at 750 °C, the X-ray diffraction, Raman and High-Resolution Transmission Electron Microscopy data converge to a single pseudo-cubic phase. However, the evolution of Eu(3+)-delayed luminescence from cubic ceria-like to tetragonal zirconia-like emission reveals the formation of CeO2- and ZrO2-rich nanodomains and provides evidence for early phase separation. For Eu(3+)-CeO2-ZrO2 calcined at 1000 °C, the emission of Eu(3+) reveals both structural and compositional inhomogeneity. Our study identifies the differences between the local structure properties of CeO2 and ZrO2 parent oxides and CeO2-ZrO2 mixed oxide, also confirming the special chemical environment of the oxygen atoms in the mixed oxide as reported earlier by Extended X-ray Absorption Fine Structure investigations.
authors.affiliation: National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG-36, Bucharest-Magurele, RO 76900, Romania. tiseanuc@yahoo.com.
authors.forename: Carmen
authors.initials: C
authors.lastname: Tiseanu
authors.forename: Vasile
authors.initials: V
authors.lastname: Parvulescu
authors.forename: Daniel
authors.initials: D
authors.lastname: Avram
authors.forename: Bogdan
authors.initials: B
authors.lastname: Cojocaru
authors.forename: Magali
authors.initials: M
authors.lastname: Boutonnet
authors.forename: Margarita
authors.initials: M
authors.lastname: Sanchez-Dominguez