BASILIO, Sabrina Kelly Trajano.
Resumo:
NiCuZn ferrites are materials that can be used in various applications in the
technological area. The application as an absorber of electromagnetic radiation has
stood out, since this material has excellent electrical and magnetic properties. Thus,
the objective of this work is to obtain the Ni0.5-xZn0.5-xCu2xFe2O4 ferrite (x = 0; 0.1;
0.15 mol of Cu) by combustion reaction on a pilot scale with 200g / batch, in order to
present nanocharacteristics suitable for use as absorbers of electromagnetic
radiation in the frequency of 8 to 12GHz. The samples were characterized by X-ray
diffraction (XRD), chemical analysis by X-ray fluorescence by dispersive energy
(EDX), infrared spectroscopy with Fourier transform (FTIR), particle size distribution,
textural analysis by nitrogen adsorption (BET), thermogravimetric analysis (TGA),
experimental density by helium gas pycnometry, scanning electron microscopy
(SEM), magnetic measurements and electromagnetic analysis. The results showed
that the single-phase NiZn and NiZnCu ferrites were only obtained after the
calcination process, and that without heat treatment, hematite appears as a
segregated phase. Crystallite sizes ranged from 24.9 to 88.7 nm. After calcination, a
denser morphology of the samples was observed. Particle sizes ranged from
approximately 19 to 175 nm. Among the non-sintered samples, the addition of 0.2
mol of Cu in the NiZn ferrite allowed an increase in the saturation magnetization,
reaching the value of 29.7 emu/g, while in the sintered samples, the highest
magnetization was achieved by the ferrite Pure NiZn, with a value of 88.4 emu / g.
The electromagnetic properties were favored both by the presence of copper and by
the heat treatment resulting in an electromagnetic absorption greater than 99% at the
frequency of 11.5 GHz for the sample sintered and doped with 0.3 mol of copper.
