Influence of heat treatment on cobalt ferrite ceramic powders

Abstract

Nanocrystalline CoFe2O4 powders were synthesized using metallic nitrates dispersed in aqueous media precipitated by stoichiometric amount of NH4OH. The obtained amorphous powder was washed, dried at 80 C degress 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 1m2g-1 while the average crystalline size varied from 17 to 100 mm 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 94nm and dropped up to 0.54 kOe with the increase in crystalline size.