Abstract:
In this work cobalt ferrite (CoFe2O4) nanoparticles were produced by combustion,
hydrothermal and glycol thermal methods. The aim is to study the effect of the synthesis
methods upon structure and magnetic properties of the obtained nanoparticles. The structure
was studied by X-rays diffraction (XRD) and high resolution transmission electron
microscope (HRTEM). XRD results confirm the formation of cubic spinel structure with
crystallite sizes of 23.296 nm, 7.910 nm and 9.168 nm for combustion, hydrothermal and
glycol thermal methods, respectively. The X-rays patterns of the studies samples were fitted
using Full Proof software program. The obtained lattice parameters were 8.339Å, 8.352 Å and
8.383 Å for combustion, hydrothermal and glycol thermal methods respectively. The lattice
parameters were also calculated using Bragg’s law from the highest intensity peak (311) and
found to be 8.3716 Å, 8.3455 Å and 8.3657 Å for combustion, hydrothermal and glycol
thermal methods, respectively. The sample prepared by combustion method showed the
lowest value of microstrain of 0.00501±0.00010. Significant correlation was observed
between microstrains and lattice parameters. The obtained images from high resolution
transmission electronic microcopy (HRTEM) confirmed the XRD results and reflected well
crystalline structure of the synthesized CoFe2O4 nanoparticles. The magnetic properties were
studied by vibrating sample magnetometer (VSM). The results showed that the highest value
of maximum magnetization of 56.06 emu/g was for the sample prepared by combustion
method. Whilst, the obtained maximum magnetizations of 47.74 emu/g and 32.71 emu/g were
for the samples prepared by hydrothermal and glycol thermal methods, respectively. The
obtained value of corecivity were 1277.6 Oe, 175.12 Oe and 199.95 Oe for the sample
prepared by combustion, hydrothermal and glycol thermal methods, respectively. It can be
concluded that various synthesis methods of nanoparticle can lead to different structural
properties and then significantly affect the magnetic properties. In particular, maximum
magnetization and corecivity increases as crystallite sizes increases.
