Structural Features of Sm- and Gd-Doped Ceria Studied by Synchrotron X-ray Diffraction and μ-Raman Spectroscopy

TitleStructural Features of Sm- and Gd-Doped Ceria Studied by Synchrotron X-ray Diffraction and μ-Raman Spectroscopy
Publication TypeJournal Article
AuthorsArtini C, Pani M, Carnasciali MMaddalena, Buscaglia MTeresa, Plaisier JRikkert, Costa GAndrea
JournalInorganic Chemistry
Volume54
Issue8
Pagination4126-4137
ISSN0020-1669
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.

Notes

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URLhttps://doi.org/10.1021/acs.inorgchem.5b00395
DOI10.1021/acs.inorgchem.5b00395
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