Estudo das propriedades magnéticas de compósito de ferrita de níquel em matriz polimérica de PVA
Ferrites are ferrimagnetic oxides that can be manufactured in different geometric shapes. Their specimen can be formed of polycrystalline ferrites (sintered body) or ferrite composites dispersed in some type of matrix (polymeric, ceramic or metallic). Poly (vinyl alcohol) is a biodegradable poly...
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| Formato: | doctoralThesis |
| Idioma: | pt_BR |
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Brasil
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/26769 |
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| Resumo: | Ferrites are ferrimagnetic oxides that can be manufactured in different geometric
shapes. Their specimen can be formed of polycrystalline ferrites (sintered body) or ferrite
composites dispersed in some type of matrix (polymeric, ceramic or metallic). Poly (vinyl
alcohol) is a biodegradable poly (vinyl acetate) derivative, useful for film making, which
exhibits chemical resistance and good mechanical properties. In this work, composite films
formed by a poly (vinyl alcohol) 99% hydrolyzed (PVA) polymer matrix were prepared as
dispersed phases of the nickel ferrite ceramic (NiFe2O4) in 10; 20; 30 and 50% (m/m)
concentrations, (m/m), respectively, for the purpose of application in the telecommunication
area. The method of combustion was used to obtain the nickel ferrite. The nickel ferrite powder
produced in the combustion was calcined at 750°C/ 2h with a heating rate of 10°C/ min. The
films were obtained by the casting method. All the products obtained were characterized by the
techniques of X-ray diffraction (XRD), Thermogravimetry (TG-DTG), Fourier Transform
Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) with EDS, Sample
Magnetometer Vibrant (MAV) and Paramagnetic Resonance Spectroscopy (RPE). The results
of XRD together with the Rietveld refinement, showed a mean crystallite size of 32.5 nm and
formation of secondary phases of Fe2O3 and NiO. The SEM spectra showed spherical and
porous particles, while the data collected from the EDS are in line with the XRD result. The
MAV magnetic measurements have characteristics of soft magnetic materials useful for
application in telecommunication technology. The EPR spectra showed the presence of groups
binding to the Fe3+
íons. |
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