Síntese e caracterização de nanocompósitos de hidróxidos de terras raras e investigação da propriedade fotoluminescente
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Data
2016-02-22
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Universidade Federal de Goiás
Resumo
Rare earth hydroxides show optical and photocatalytic properties, and potential application as
contrast agents and biomarkers. In this study, the start materials, samarium hydroxide
(Sm(OH)3) and gadolinium hydroxide (Gd(OH)3), were synthesized at room temperature by
precipitation method and using microwave-assisted hydrothermal (MAH) method for 20
minutes. Pure hexagonal phase with an anisotropic hexagonal nanotubes morphology was
obtained, with dimensions of 200-350 nm x 30-40 nm to Sm(OH)3, and 570-990 nm x 90-245
nm for Gd(OH)3. Hydroxides doped and nanocomposites in the form of TR(OH) 3/TR(OH)3,
were synthesized as hybrid systems. Nanocomposites Sm(OH) 3/Gd(OH)3 e Gd(OH)3/Sm(OH)3
were obtained in differents ratios by two step synthesis by MAH method, resulting in
decorated nanotubes as nanocomposites the ordered/disordered type. The structural and
morphological characterization of materials were carried out by X-ray Diffraction (XRD),
Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Atoms
constituents of phases were confirmed by Energy Dispersive X-Ray Spectroscopy (EDS).
Nanocomposites of Sm(OH)3 and Sm(OH)3 were also synthesized by sonochemical method,
which enabled obtain both crystalline phases. The photoluminescent property of the materials
was investigated by photoluminescence spectroscopy (PLS) in which was observed the
broadband photoluminescence enhancement for both doped hydroxides as for
nanocomposites. The latter provides the best results. The composite Sm/Gd-20-A
showed photoluminescence up to seven times more intense than the pure precursor
hydroxides due to interfacial defects.
Descrição
Palavras-chave
Hidróxidos de terras raras, Nanocompósitos, Microondas, Método hidrotérmico, Síntese sonoquímica, Fotoluminescência, Rare earth hydroxides, Nanocomposites, Microwave, Hydrothermal method, Sonochemistry synthesis, Photoluminesce
Citação
SANTOS, M. A. B. Síntese e caracterização de nanocompósitos de hidróxidos de terras raras e investigação da propriedade fotoluminescente. 2016. 116 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Catalão, 2016.