Document Type: Research Paper
Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran.
Current study represents the effect of the size and synthesis method on the cation distribution of cobalt ferrite nanoparticles and on the magnetic properties. The nanoferrites have been synthesized through sol-gel auto-combustion method using metal nitrates as precursor and citrate as fuel. In order to obtain the fine and agglomerated-free particles, we have used salt-assisted combustion reaction method. Magnetic properties of the synthesized single phase cobalt ferrite nanoparticles are carried out using vibrating sample magnetometer (VSM) at room temperature. It has been observed that the coercivity and saturation magnetization of the samples reduced by adding salt. The transmission electron microscopy (TEM) confirms the finer nanoparticles formation from around 70-200 nm to 10-40 nm. Structural characterization is done by X-ray diffraction (XRD) and it confirms the spinel structure formation for the samples. The crystallite size and induced strain were derived from the XRD patterns by Williamson-Hall (W-H) method. The magnetic parameters were reduced by crystallite size reduction from 38.5 nm to 11 nm. The further analysis of XRD peaks is fulfilled using Rietveld refinement in order to explain the magnetic properties. The obtained Rietveld refined data allow us to measure the distribution of cations within the available octahedral and tetrahedral sites.