Structural and magnetic properties of cobalt ferrite nanoparticles synthesized by auto–combustion sol–gel method

Abstract

The present study reports the synthesis of cobalt ferrite (CoFe2O4; CFO) nanoparticles using the auto–combustion sol–gel method, aimed at investigating their structural and magnetic properties. X–ray diffraction (XRD) measurement reveals the single–phase nature of the CFO nanoparticles. Various aspects of the structure of the CFO nanoparticles have been analyzed on the basis of the Nelson–Riley (N–R) method, Scherrer’s plot, Williamson–Hall (W–H) method and the Size–Strain plot. The magnetization–magnetic field (M–H) loop, influenced by particle size, does not exhibit saturation in magnetization. Saturation magnetization ∼ 70.89 emu/gm has been estimated using the Law of Approach to Saturation (LoAS) method, along with a magnetocrystalline anisotropy ∼ 5.56 × 106 erg/cm3 for the CFO nanoparticles. Temperature dependent magnetization measurements under zero–field–cooled (ZFC) and field–cooled (FC) protocols demonstrate that the CFO nanoparticles exhibit the blocking temperature (TB) characteristic of superparamagnetic nanoparticles at ∼ 150 K.