Síntese, caracterização e estudo das propriedades magnéticas de CoFe(2-x)YxO4, 0≤x≤0,05, produzidas por reação de combustão
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2013-07-23
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Universidade Federal de Goiás
Resumo
Compounds of CoFe(2-x)YxO4, with 0 x 0.05, were synthesized by
combustion reaction. On the synthesis we used as oxidizing reagents, iron
nitrate Fe(NO3)3.9H2O, cobalt nitrate Co(NO3)2.6H2O, yttrium nitrate
Y(NO3)3.6H2O and as a fuel reducer, was used urea CO(NH2)2 with 300% in
excess. Post nanometric of cobalt ferrite in the spinel structure was obtained,
wich formed crystalline aggregates, with crystallite average size of 20 ± 3 nm.
The results of X-ray diffraction showed well defined diffraction peaks
characteristic of the pure phase CoFe2O4, not showing secondary phase for
all the compounds stoichiometries. The infrared spectra showed bands
characteristic of the metal and the oxygen bonds in the octahedral and
tetrahedral sites around 590-600 cm-1 and 400 cm-1 respectively, as well as,
shifting of the same to higher frequencies, also showed bands relating to
residual compounds bonds of the synthesis stage, that was eliminated during
the heating to obtain the thermograms. The thermograms showed the
material chemical stability and the residual compounds elimination and the
crystallization of the same starting at 400°C. The micrographs achieved
through transmission electron microscopy showed crystalline agglomerates
and using the program Image J. was possible to make 301 counts of the
particles diameters and to obtain a mean value for the sample x = ~ 1.5% of
18.58 nm, close to that obtained by the Scherrer equation, which for this
sample was ~19 nm. The scanning electron microscopy via Energy
Dispersive Spectrometer (EDS) was used to determine the chemical
composition of the experimental material, and along with the stoichiometric
calculate the values were tabulated. The data exposed in the table showed
an agreement with the calculated values whit the obtained. The magnetic
analysis revealed that the samples show the typical ferrimagnetism of the compound nature dependent of the Y3+ concentration.
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NASCIMENTO, Thaísa Cardoso. Síntese, caracterização e estudo das propriedades magnéticas de CoFe(2-x)YxO4, 0≤x≤0,05, produzidas por reação de combustão. 2013. 76 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Goiânia.