Papers by Author: S. Alves

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Authors: Ana Claudia V. De Araújo, S. Alves, W.M. Azevedo
Abstract: In this work we report the preparation and characterization of a polyaniline/magnetite (PANI)-Fe3O4 nanocomposite, with average diameter around 50 nm and tubular morphology. The tubular nanocomposite was synthesized by an in situ polymerization of aniline using Fe3O4 nanoparticles as an oxidant agent. The Fe3O4 nanoparticles with narrow size distribution were synthesized by co-precipitation technique and the products were characterized by powder X-ray diffractometry (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).
Authors: C. de Mello Donegá, S. Alves, O.L. Malta, G.F. de Sá
Authors: C.G. Gameiro, E.F. da Silva Jr., S. Alves, G.F. de Sá, P.A. Santa-Cruz
Authors: T.S. Barros, Bráulio Silva Barros, S. Alves, Ruth Herta Goldsmith Aliaga Kiminami, Hélio Lucena Lira, Ana Cristina Figueiredo de Melo Costa
Abstract: Zinc oxide was obtained by combustion reaction synthesis method using microwaves energy to provide ignition to the mixture of zinc nitrate, europium and urea. The influence of the europium concentration on the structure, morphology and luminescence characteristics of the ZnO powders was investigated. The proportion of each reagent and fuel was calculated based on the propellants chemistry concepts. The solutions were mixed in a vitreous silica basin and submitted of external heating in a microwaves oven until self-ignition occurred. The resulting powders were characterized by X-ray diffractometer (XRD), granulometric distribution, scanning electronic microscopy (SEM) and emission spectroscopy. The XRD results showed the formation of ZnO:Eu3+ as main phase and Eu2O3 as secondary phase. The powder presented morphology constituted of fine particles agglomerates (<100nm) and red luminescence characteristic from Eu3+ ion.
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