Abstract
Nickel ferrite (NiFe204) nanoparticles were synthesized by the proteic
sol gel method at synthesis temperature of 250 degrees C, 300 degrees C
and 400 degrees C, with the objective of obtaining superparamagnetic
nanoparticles. Thermogravimetric analysis (TGA) and
temperature-programed oxidation (TPO) presented peaks around 290 degrees
C indicating that nickel ferrite was forming at this temperature. X-ray
powder diffraction (XRPD) confirmed that the polycrystalline sample was
single phased NiFe2O4 with space group Fd3m. Scherrer equation applied
to the diffraction patterns and transmission electron microscopy (TEM)
images showed that the size of the nanoparticles ranged from 9 nm to 13
nm. TEM images also revealed that the nanoparticles were agglomerated,
which was supported by the low values of surface area provided by the
Brunauer-Emmet-Teller (BET) method. Mossbauer spectroscopy presented
spectra composed of a superposition of three components: a sextet, a
doublet and a broad singlet pattern. The sample synthetized at 300
degrees C had the most pronounced doublet pattern characteristic of
superparamagnetic nanoparticles. In conclusion, this method was
partially successful in obtaining superparamagnetic nickel ferrite
nanoparticles, in which the synthetized samples were a mixture of
nanoparticles with blocking temperature above and below room
temperature. Magnetization curves revealed a small hysteresis,
supporting the Mossbauer results. The sample with the higher
concentration of superparamagnetic nanoparticles being the one
synthetized at 300 degrees C. (C) 2015 Elsevier B.V. All rights
reserved.
Users
Please
log in to take part in the discussion (add own reviews or comments).