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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Obtenção de prata nanoestruturada a partir da redução mecano-química de 𝐴𝑔2𝑂

Bezerra, Meg Caroliny dos Santos, 92-99192-9864 16 January 2017 (has links)
Submitted by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-08-25T14:24:55Z No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação Parcial (Cap.1 a 5) - Meg C. S. Bezerra.pdf: 2265801 bytes, checksum: 27101837915da2598de1bc917e58d461 (MD5) Dissertação Parcial (Cap. 7,8,9) - Meg C. S Bezerra.pdf: 311607 bytes, checksum: bc1c1e77ac88270ffb7adaccca509e0d (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-08-25T14:27:05Z (GMT) No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação Parcial (Cap.1 a 5) - Meg C. S. Bezerra.pdf: 2265801 bytes, checksum: 27101837915da2598de1bc917e58d461 (MD5) Dissertação Parcial (Cap. 7,8,9) - Meg C. S Bezerra.pdf: 311607 bytes, checksum: bc1c1e77ac88270ffb7adaccca509e0d (MD5) / Made available in DSpace on 2017-08-25T14:27:05Z (GMT). No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação Parcial (Cap.1 a 5) - Meg C. S. Bezerra.pdf: 2265801 bytes, checksum: 27101837915da2598de1bc917e58d461 (MD5) Dissertação Parcial (Cap. 7,8,9) - Meg C. S Bezerra.pdf: 311607 bytes, checksum: bc1c1e77ac88270ffb7adaccca509e0d (MD5) Previous issue date: 2017-01-16 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / The mixture of the precursor element Ag2O with three different process control agents (carbon, glycerine and polyethylene), each mixture called route 1, route 2 and route 3 respectively, were synthesized using the mechanochemical technique. In all synthesis routes the silver oxide was reduced in silver, but one route with greater efficiency than another. The evolution of the structural properties of the samples for the routes of the process control agents (PCA) was studied by the X - ray diffraction (XRD) technique, at each time interval of mechanochemical synthesis a measurement of XRD was performed. The presence of silver carbonate (contaminant) in all ACP routes was identified, with increasing milling time there is a decrease but not dissipation. From the structural refinements by the Rietveld method using the GSAS software, the average crystallite size of routes 1, route 2 and route 3 was estimated, where the mean crystallite size for each route at the end of the synthesis was 13 nm, 22 nm and 12 nm, respectively. Differential Scanning Calorimetry (DSC) analysis was performed on all samples for thermal stability analysis. The heat treatment was carried out for one hour at 300 ° C under inert atmosphere, the XRD measurement was performed on the residue, which revealed dissipation of the silver carbonate. The morphology of the synthesized samples was investigated using scanning electron microscopy (SEM), the technique was applied in the untreated and thermally treated samples, route 1 shows a leaf shape morphology and the flake shape route 2, both with size of irregular grains. The FTIR technique was applied to identify if there were still organic compounds in nanostructured silver. / A partir da mistura do elemento precursor Ag2O com três diferentes agentes de controle de processo (carbono, glicerina e polietileno), cada mistura chamada de rota 1, rota 2 e rota 3 respectivamente, foram sintetizados usando a técnica de mecano – química. Em todas as rotas de síntese o óxido de prata foi reduzido em prata, porém uma rota com maior eficiência que outra. A evolução estrutural das amostras para as rotas dos agentes de controle de processo (ACP) foram estudadas através da técnica de difração de raios X (DRX). Cada intervalo de tempo do processo mecano - químico uma medida de DRX foi realizada e a partir dos refinamentos estruturais pelo método de Rietveld, usando o software GSAS, estimou-se os tamanhos médios de cristalitos das rotas 1, rota 2 e rota 3, onde o tamanho médio de cristalito para cada rota ao final da síntese foi de 13 nm, de 22 nm e 12nm, respectivamente. A análise de calorimetria diferencial de varredura (DSC) foi realizada em todas as amostras para análise da estabilidade térmica. Um tratamento térmico foi realizado durante uma hora a 300° C sob atmosfera inerte, revelando a dissipação do carbonato de prata. As morfologias das amostras foram investigadas usando microscopia eletrônica de varredura (MEV). A amostras não tratadas e tratadas termicamente, da rota 1 apresenta uma morfologia em forma de folhas e a rota 2 em forma de flocos, ambas com tamanhos de grãos irregulares. A técnica de FTIR foi aplicada para identificar se ainda havia compostos orgânicos na prata nanoestruturada.

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