Abstract
Annealed cobalt inverse spinel-type ferrite nanoparticles were synthesized using polyethylene glycol assisted co-precipitation. The structure, magnetic properties and effect of annealing temperature was investigated in detail. Saturation magnetization, coercivity and remanence magnetization were observed to decrease with increasing temperature. The magnetic hysteresis curves supported the proposition that the CoFe2O4 nanoparticles showed ferromagnetic character from 10 to 400 K. Magnetization measurements showed the blocking temperature to be higher than 400 K. Unsaturated magnetization behavior suggested the existence of disordered spins in the surface layer of the CoFe2O4 nanoparticles.