EDUARDO CAETANO CAMILO DE SOUZA
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Artigo IPEN-doc 14071 Synthesis and characterization of spherical and narrow size distribution indium oxide nanoparticles2009 - 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.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.