EDUARDO CAETANO CAMILO DE SOUZA
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Artigo IPEN-doc 08616 Synthesis of reactive neodymia-doped zirconia powders by the sol-gel technique2002 - MUCCILLO, E.N.S.; SOUZA, E.C.C.; MUCCILLO, R.Artigo IPEN-doc 14484 Effect of solvent on physical properties of samaria-doped ceria prepared by homogeneous precipitation2009 - SOUZA, E.C.C.; MUCCILLO, E.N.S.Samaria-doped ceria solid solutions were prepared by homogeneous precipitation with hexamethylenetetramine using water and mixtures of alcohol/water as solvent. The mixed solvent influences several physical properties of the synthesized material when compared to those of samples prepared in water. The solid solution is formed, at least partially, during precipitation as demonstrated by Raman spectroscopy data. The dried precipitate is crystalline and single phase with fluorite-type structure, and consists of a mixture of anhydrous and hydrated cerium oxide with average sizes in the 5-8 nm range. Thermal decomposition of the as-synthesized material occurs at 400 °C. High densification was obtained at low temperatures (∼1200 °C). The electrical conductivity of grains and grain boundaries is improved for synthesized samples when compared to specimens prepared by mixing of starting oxides. These improved characteristics of synthesized powders are attributed to the interaction among the solvent and hydroxyl and water species on the surface of nanoparticles. The strength of this interaction is related to the carbon content in the alcohol chain.Artigo IPEN-doc 14482 Optical and electrical characterization of samaria-doped ceria2010 - SOUZA, E.C.C.; BRITO, H.F.; MUCCILLO, E.N.S.Ce0.8Sm0.2O1.9 andCeO2 nanomaterials were prepared by a solution technique to produce an ultrafine particulate material with high sinterability. In this work, the structural characteristics, the photoluminescent behavior and the ionic conductivity of the synthesized materials are focused. The thermally decomposed material consists of less than 10 nm in diameter nanoparticles. The Raman spectrum of pure CeO2 consists of a single triple degenerate F2g model characteristic of the fluorite-like structure. The full width at half maximum of this band decreases linearly with increasing calcination temperature. The photoluminescence spectra show a broadened emission band assigned to the ligand-to-metal charge-transfer states O→Ce4+. The emission spectra of the Ce0.8Sm0.2O1.9 specimens present narrow bands arising from the 4G5/2 →6HJ transitions (J=5/2, 7/2, 9/2 and 11/2) of Sm3+ ion due to the efficient energy transfer from the O→Ce4+ transitions to the emitter 4G5/2 level. The ionic conductivity of sintered specimens shows a significant dependence on density.