EDUARDO CAETANO CAMILO DE SOUZA

EDUARDO CAETANO CAMILO DE SOUZA

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Synthesis and characterization of spherical and narrow size distribution indium oxide nanoparticles
2009 - SOUZA, E.C.C.; REY, J.F.Q.; MUCCILLO, E.N.S.
This work reports the synthesis of indium oxide nanoparticles and their thermal, structural, microstructural and optical characterization. The preparation method is based on a surfactant-free room temperature soft chemistry route. Spherical indium oxide nanoparticles (about 8 nm in diameter) were obtained after thermal treatment of gels at 400 ºC for 2 h, as shown by X-ray diffraction experiments and nitrogen adsorption measurements. Transmission electron microscopy observations confirm the single-crystalline nature of the produced nanoparticles. The photoluminescence emission spectrum at room temperature shows a broad peak with onset at approximately 315 nm as a result of quantum size effect as revealed by small-angle X-ray scattering.
Effect of solvent on physical properties of samaria-doped ceria prepared by homogeneous precipitation
2009 - 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.
Optical and electrical characterization of samaria-doped ceria
2010 - 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.
Solid solution formation, densification and ionic conductivity of Gd- and Sm-doped ceria
2011 - REIS, S.L.; SOUZA, E.C.C.; MUCCILLO, E.N.S.
Influence of neodymium ions on photocatalytic activity of TiOsub(2) synthesized by sol-gel and precipitation methods
2011 - HEWER, T.L.R.; SOUZA, E.C.C.; MARTINS, T.S.; MUCCILLO, E.N.S.; FREIRE, R.S.
Ionic and electronic conductivity of nanostructured, samaria-doped ceria
2012 - SOUZA, E.C.C.; CHUEH, W.C.; JUNG, W.; MUCCILLO, E.N.S.; HAILE, S.M.