Navegando por Autor "Santos, Maria Aparecida Bezerra dos"

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    Síntese e caracterização de nanocompósitos de hidróxidos de terras raras e investigação da propriedade fotoluminescente
    (Universidade Federal de Goiás, 2016-02-22) Santos, Maria Aparecida Bezerra dos; Godinho Junior, Mario; http://lattes.cnpq.br/8364676654739392; Godinho Junior, Mario; Lima, Renata Cristina de; Santos, Maria Rita de Cássia
    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.