Effect of Al3+ Doping on the Microstructure and Magnetic Behavior of CoFe2O4 Nanoparticles

Abstract

This is the study of CoFe₂O₄ and CoAl_0.2Fe_1.8O₄ ferrite nanoparticles synthesized by sol–gel method, and their structural and magnetic properties with aluminum doping are studied here. Metal nitrates of high purity were used as chelating and polymerization agents along with citric acid and ethylene glycol for the synthesis. The insertion of Al³⁺ ions into the structure was confirmed by XRD in the present study, where values of lattice parameters decreased and crystallite size decreased. The FT-IR result indicated the same that the Al³⁺ ions sample has the better metal–oxygen bond. The SEM–EDS results indicated that the addition of Al³⁺ resulted in finer particles relative to the undoped sample. Saturation magnetization, Ms, was reduced from 80 emu/g to 70 emu/g; Hc was decreased to 650 Oe to 500 Oe; and the anisotropy constant K1 was decreased to 1.2 × 10⁶ erg/cm³ to 9.5 × 10⁵ erg/cm³ from VSM result confirming the lower magnetic hardness due to the Al³⁺ doping. Based on the study results, it is clear that the dope of the Al³⁺ donor has a dramatic effect on the properties of ferrite nanoparticles.