Navegando por Autor "Lima, Renata Cibely Freire de"
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Artigo Effect of process parameters on photophysical properties and barium molybdate phosphors characteristics(Elsevier, 2014) Abreu, Maria Fernanda C.; Motta, Fabiana Villela da; Lima, Renata Cibely Freire de; Li, Maximo S.; Longo, Elson; Marques, Ana Paula de A.Barium molybdate particles (BaMoO4) with uniform shapes have applications in various fields such as phosphors, optical fibers, scintillators, magnets and catalysts. In this study, two synthesis methods (microwave-assisted hydrothermal (MAH) and Complex Polymerization (CP)) were used to prepare BaMoO4 particles. The effect of the applied synthesis methodology and experimental parameters on the morphology, particle size, sample uniformity and optical properties of the BaMoO4 were studied. Scheelite-type single crystalline structures of BaMoO4 were identified by X-ray diffraction (XRD) as well as Raman and Fourier transform infrared spectroscopy (FTIR). Octahedral morphologies were characterized by field-emission scanning electron microscopy (FE-SEM). Photoluminescence (PL) spectra of the samples exhibited different emission properties which indicates a relationship with surface defect states (shallow and deep level defects) where interfaces populate additional levels in the band gap. Electronic order-disorder at short- and intermediate-ranges is generated by utilizing the synthesis method and can be modified by applied experimental parameters. If the particle size and morphology are controlled, deep and shallow defects can be controlled, and PL properties can be modified accordingly with the optical properties desiredArtigo Effects of microwave-assisted hydrothermal treatment and of use of capping reagent on the photophysical properties of SrMoO4 phosphors(Springer, 2017-12) Paradelas, Sidney M.V.; Gonçalves, Rosana F.; Motta, Fabiana Villela da; Lima, Renata Cibely Freire de; Li, Maximo S.; Longo, Elson; Marques, Ana Paula de A.Strontium molybdate particles (SrMoO4) with uniform shapes have applications in various fields such as phosphors, optical fibers, scintillators, magnets, sensors, and catalysts. SrMoO4 were prepared by Microwave-Assisted Hydrothermal (MAH) method with variations in applied experimental parameters. The effect of the applied synthesis methodology and experimental parameters on the morphology, particle size, sample uniformity and optical properties of the SrMoO4 were studied. In this study, was observed that the microwave radiation favors an organization of material and that this organization can be changed with a capping agent, which provokes alterations in morphology, a disorder-order degree of material and variations of band gap energy. This study indicates that surface defect states favor an alteration in properties of the PL emission. The control of a surface state, the particle size and morphology can be a form to modify the property in accordance with optics characteristics the desired one.TCC Síntese Eco-Friendly: Transformando Clinoptilolita em zeólita do tipo LTA(Universidade Federal do Rio Grande do Norte, 2021-09-10) Lima, Renata Cibely Freire de; Pergher, Sibele Berenice Castellã; Oliveira, Daniele da Silva; http://lattes.cnpq.br/2513575106175219; http://lattes.cnpq.br/5249001430287414; http://lattes.cnpq.br/6117670920893429; Oliveira, Fernando José Volpi Eusébio de; http://lattes.cnpq.br/5600786330033497; Bieseki, Lindiane; http://lattes.cnpq.br/4894556873583410A Clinoptilolita é um aluminossilicato, com estrutura zeolítica, encontrada em grandes quantidades na natureza, entretanto pouca explorada. Para ampliar as aplicações deste material, uma alternativa seria empregar essa zeólita natural para a síntese de zeólita de maior interesse industrial como uma zeólita de estrutura LTA. Com isso, o objetivo desse trabalho foi utilizar a Clinoptilolita como fonte alternativa na síntese da zeólita LTA, variando as condições de síntese. A Clinoptilolita foi utilizada como fonte alternativa de silício e alumínio na síntese da zeólita tipo LTA, variando o tempo de cristalização de 1 h a 6 h a 100 ºC em meio estático. As amostras obtidas foram caracterizadas por difração de raios-X (DRX), fluorescência de raios-X (FRX), espectroscopia na região do infravermelho com transformada de Fourier (FTIR) e microscopia eletrônica de varredura (MEV). A partir dos resultados obtidos foi possível observar que as sínteses foram realizadas com êxito. A utilização da Clinoptilolita na síntese de zeólitas é um processo inovador, economicamente viável e ambientalmente correto, valorizando um material que existe em grande quantidade e que ainda é pouco explorado pelas indústrias.