Influence of heat treatment on cobalt ferrite ceramic powders

Abstract

Nanocrystalline CoFe 2O 4 powders were synthesized using metallic nitrates dispersed in aqueous media precipitated by stoichiometric amount of NH 4OH. The obtained amorphous powder was washed, dried at 80 °C and heat-treated at various temperatures for 2 h for crystallization of the material. The influence of heat treatment on the texture and morphology of the cobalt ferrite powder was studied. The specific surface area varied from 150 to 1 m 2 g −1 while the average crystallite size varied from 17 to 100 nm with the annealing temperature. The corresponding saturation magnetization value at room temperature varied from 25.9 to 60.3 emu g −1 and the coercivity increases up to 1.5 kOe when the crystallite size reached 94 nm and dropped up to 0.54 kOe with the increase in crystallite size.