Size Induced Structural and Magnetic Properties of Nanostructured Cobalt Ferrites Synthesized by Co-precipitation Technique

Abstract

Cobalt ferrite (CoFe₂O₄), a well-known hard magnetic material high frequency applications and high-density recording media. Due to their good chemical and thermal stability, high permeability, high electrical resistivity, high saturation magnetization and coercivity etc. they found wide technological applications. Size dependent properties of CoFe₂O₄ include catalytic properties, electrochemical properties, magnetic properties and optical properties. Thermally induced changes in nanocrystalline CoFe₂O₄spinel ferrites were synthesized by co-precipitation technique. Unlike other techniques, co-precipitation is reported to be the most economical and successful technique for synthesizing ultrafine CoFe₂O₄powders having narrow particle size distribution. Their structural and magnetic properties were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) measurements. The average crystallite size of CoFe₂O₄was observed to increase from 23 to 65 nm as the annealing temperature was increased from 300 to 900°C. The lattice parameters were observed to increase due to increase in the crystallite size. The activation energy (E) of nanostructured CoFe₂O₄ was observed to be 11.6 kJ/mol. The annealing temperature has a prominent effect on the nanocrystallite growth. The saturation magnetization, coercivity and remanence were observed to increase with increasing crystalite size. In our future work, we plan to synthesize nanocrystalline CoFe₂O₄ using different techniques in order to understand the role of synthesis techniques on the structural and magnetic properties.