Magnetic properties of thermal plasma synthesized nanocrystalline nickel ferrite (NiFe2O4)

A rapid synthesis method is reported for magnetic nanoparticles of nickel ferrite involving thermal plasma assisted vapor phase condensation process. The as-synthesized samples were characterized by X-ray Diffraction, Transmission Electron Microscopy, Vibrating Sample Magnetometer and X-ray Photoelectron Spectroscopy techniques. The average particle size was determined from the TEM micrographs and found to be around 30 nm. The effects of reactor parameters on the magnetic and structural properties have been evaluated, to find the optimized parameters so as to achieve the highest values of saturation magnetization and coercivity. Reasonably high saturation magnetization (48 emu/g) has been assigned to the high degree of crystallinity, achieved on account of high temperature during the growth, and the cation redistribution. The high value of coercivity (115 Oe) is explained on the basis of possible lattice defects arising from the cation redistribution. Detailed analysis of cation distribution using the XRD line intensity data leads to the conclusion that these samples are iron deficit and nickel rich.

Research highlights
► A rapid synthesis method is reported for nano magnetic particles of nickel ferrite involving direct current transferred arc thermal plasma assisted vapor phase condensation process.
► The as synthesized nanoparticles of NiFe2O4 are found to be polycrystalline in nature with average particle size of 30 nm; as revealed by the TEM analysis.
► The saturation magnetization and coercivity values of the as synthesized particles are found to be dependent on the different operating parameters on account of the cation distributions.
► Reasonably high saturation magnetization (48 emu/g) has been assigned to the high degree of crystallinity, achieved on account of high temperature during the growth, and the cation redistribution.