Influence of heat treatment on cobalt ferrite ceramic powders

Nanocrystalline CoFe2O4 powders were synthesized using metallic nitrates dispersed in aqueous media precipitated by stoichiometrie amount of NH4OH. The obtained amorphous powder was washed, dried at 80 degreesC and heat-treated at various temperatures for 2 It 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 mn 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. (C) 2004 Elsevier B.V. All rights reserved.