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Master's Dissertation
DOI
https://doi.org/10.11606/D.85.2019.tde-07022019-161716
Document
Author
Full name
Tayná de Fatima Amorim da Silva
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2018
Supervisor
Committee
Baldochi, Sonia Licia (President)
Linhares, Horacio Marconi da Silva Matias Dantas
Macêdo, Zélia Soares
Title in Portuguese
Estudo da síntese de nanopartículas de NaYF4:Yb:Er a partir de circuito microfluídico projetado no IPEN
Keywords in Portuguese
fluoretos
nanopartículas
sistemas microfluídicos
usinagem a laser
Abstract in Portuguese
Este trabalho apresenta a síntese de nanopartículas (NPs) de NaYF4 dopadas com íons terras raras a partir de sistemas microfluídicos projetados e desenvolvidos em parceria entre o Laboratório de Crescimento de Cristais e a Central de Processamento de Materiais a Laser no Centro de Laser e Aplicações IPEN. O objetivo foi o estudo de diferentes circuitos microfluídicos usinados a laser para síntese de NPs de fluoretos em geral. Como material teste foi escolhido o NaYF4:Yb3+:Er3+, visando sua obtenção na fase hexagonal com dimensões definidas. Experiências de síntese deste material por co-precipitação, sem uso de surfactantes, foram realizadas para comparação com as sínteses obtidas via microfluídica. Por co-precipitação foram obtidas partículas esféricas, na fase cubica do NaYF4. Foram projetados e fabricados, via usinagem a laser de pulsos ultracurtos em substrato de vidro ótico BK7, três circuitos microfluídicos. Nas experiências de sínteses realizadas nestes chips foram obtidas NPs de NaYF4:Yb3+:Er3+ tanto na fase cubica quanto na fase hexagonal, em diferentes proporções, dependendo dos fluxos de injeção dos precursores no micro reator, da temperatura e da taxa de residência. As NPs obtidas neste trabalho foram caracterizadas através de DRX e analise pelo método de Rietveld, para a identificação das fases do material, MET para definição de forma e tamanho da nanopartículas e MEV para estudo dos microcanais dos chips usinados a lasers. Os melhores resultados foram observados em chips com microcanais da ordem de 400-600μm, pois minimizam o problema de obstrução. Contudo, o controle da temperatura precisa ser otimizado para evitar trincas nos microcircuitos. As NPs obtidas via microfluídica apresentaram distribuição de tamanho na faixa de 5 a 200nm e fases com estrutura hexagonal e cubica. Foi possível obter NPs de fase única cubica, mas o mesmo não ocorreu para fase hexagonal do NaYF4. O presente estudo permitiu definir vários fatores para a obtenção das NPs de NaYF4 via microfluídica e também referente a fabricação, montagem e uso dos chips, porém para obter NPs desse material com controle da dimensão e fases serão necessários estudos complementares.
Title in English
Study of NaYF4:Yb:Er nanoparticles synthesis through microfluidic systems fabricated at IPEN
Keywords in English
fluorides
laser machining
microfluidics chips
nanoparticles
Abstract in English
This work presents the synthesis of NaYF4 nanoparticles (NPs), doped with rare earth ions, using microfluidic systems designed and fabricated at IPEN through Crystal Growth Lab and Materials Laser Processing Lab partnership. The aim of this work was the study of different microfluidic chips laser machined for use in fluoride NPs synthesis. The compound NaYF4:Yb3+:Er3+ (Yb 10 mole%; Er 0.5 mole %) was chosen to test the fabricated microfluidic chips aiming the production of NPs with hexagonal structure with defined dimensions. Synthesis experiments by co-precipitation method of this material without any surfactant were performed to compare with microfluidics synthesis. By this method spherical particles, were obtained with the cubic NaYF4 crystalline structure. Three different chips were designed and fabricated, using a femtosecond laser to machine BK7 optical glass substrate. The synthesis experiments with these chips resulted in NaYF4:Yb3+:Er3+ NPs with both cubic and hexagonal crystalline structure, in different proportions, depending of precursors flux rates, temperature and resident time. The obtained materials of all experiments were characterized by X-ray diffraction and Rietveld analysis, to define crystalline structures parameters; transmission microscopy to define shape and size of NPs and scanning electron microscopy to characterize the chips micro channels machined by laser. The best results were observed for chips with channels of 400-600μm, in view of the obstruction decrease in the chips. The NPs obtained with microfluidics presented sizes from 5nm up to 200nm and hexagonal and cubic crystallographic structures. Cubic single phase NPs were obtained, but the same did not happened with the NaYF4 hexagonal phase. The present study allowed establishing many different parameters for NaYF4 NPs synthesis through microfluidics and concerning fabrication, assembly and experimental use of microfluidic chips, however, additional experiments will be necessary to obtain the fluoride NPs with controlled size and shape.
 
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Publishing Date
2019-03-13
 
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