title: Structural features of Sm- and Gd-doped ceria studied by synchrotron X-ray diffraction and μ-Raman spectroscopy.
abstract: A structural study of Sm- and Gd-doped ceria was performed with the aim to clarify some unexplained structural features. (Ce1-xREx)O2-x/2 samples (RE ≡ Sm, Gd; x = 0, 0.1, ..., 1) were prepared by coprecipitation of mixed oxalates and subsequent thermal treatment at 1473, 1173, or 1073 K in air; they were then analyzed at room temperature both by synchrotron X-ray diffraction and μ-Raman spectroscopy. Two structural models were adopted to fit the experimental data, namely, a fluoritic one, resembling the CeO2 structure at low RE content, and a hybrid one at higher RE content, intermediate between the CeO2 and the RE2O3 structures. Two main transitions were detected along the compositional range: (a) an RE-dependent transition at the boundary between the fluoritic and the hybrid regions, of a chemical nature; (b) an RE-independent transition within the hybrid region at ∼0.5, having a purely geometrical nature. The presence of two finely interlaced F- and C-based structures within the hybrid region was confirmed, and hints of their composition were obtained by μ-Raman spectroscopy. The obtained results indicate a possible explanation for the non-Vegard behavioral trend of the cell parameters.
authors: †DCCI, Department of Chemistry and Industrial Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova, Italy.|‡CNR-IENI, Via De Marini 6, 16149 Genova, Italy.
authors: Cristina
authors: C
authors: Artini
authors: †DCCI, Department of Chemistry and Industrial Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova, Italy.|§CNR-SPIN Genova, Corso Perrone 24, 16152 Genova, Italy.
authors: Marcella
authors: M
authors: Pani
authors: †DCCI, Department of Chemistry and Industrial Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova, Italy.|∥INSTM, Genova Research Unit, Via Dodecaneso 31, 16146 Genova, Italy.
authors: Maria Maddalena
authors: MM
authors: Carnasciali
authors: ‡CNR-IENI, Via De Marini 6, 16149 Genova, Italy.
authors: Maria Teresa
authors: MT
authors: Buscaglia
authors: ⊥Elettra - Sincrotrone Trieste S.C.p.A., ss 14, km 163.5, 34149 Basovizza, Trieste, Italy.
authors: Jasper Rikkert
authors: JR
authors: Plaisier
authors: †DCCI, Department of Chemistry and Industrial Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova, Italy.|§CNR-SPIN Genova, Corso Perrone 24, 16152 Genova, Italy.
authors: Giorgio Andrea
authors: GA
authors: Costa