Investigation of Structure and Magnetic Properties of Cobalt Ferrite Nanoparticles Prepared by Combustion, Hydrothermal and Glycol thermal Methods

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.