Magnetic nanocomposites: Preparation and characterization of Co-ferrite nanoparticles

Cobalt ferrite nanoparticles, CoFe2O4, are one of the important spinel ferrites due to their high cubic magnetocrystalline anisotropy, high coercivity and moderate saturation magnetization. CoFe2O4 nanoparticles have been known to be a photomagnetic material which shows an interesting light induced coercivity change. In this study, various preparation techniques were used to produce cobalt ferrite nanoparticles namely, (i) ball milling of a homogeneous mixture of cobalt(II) acetate, and iron(III) acetate (basic) treated by a novel self flash combustion, (ii) precipitation of cobalt(II) chloride (CoCl2·6H2O) and iron(III) chloride (FeCl3), and (iii) ceramic method by firing of cobalt oxide (CoO) and iron oxide (Fe2O3). These techniques help to obtain particle sizes ranging from a few micrometers to about 20 nm. Thermal analysis (TGA and DTA), X-ray diffraction, SEM, TEM, magnetic and surface area measurements have been used for characterization of the prepared samples. Results showed that saturation magnetic flux density (Bs) and remnant magnetic flux density (Br) varied with crystallite size from 6.929 to 14.91 and 2.73 to 8.146 emu/g, respectively. The measured surface area (SBET) for the prepared Co-ferrite particles ranged from 5.327 to 47 m2/g. The effect of different nanosizes on the total pore volume, adsorption energy, average pore diameter, micro pore volume, have been studied. Nanocrystalline CoFe2O4 showed a catalytic activity towards CO2 decomposition with the formation of carbon nanotubes.