| Ferrites is a conventional magnetic materials, which has been widely used in many areas, such as message recording, communication, magnetc sensor, aviation etc. In this paper, two kinds of method have been used to prepare cobalt ferrite, the main work been done is as follows:Firstly, based on the nanocasting approach, large specific surface area, highly crystallined mesoporous CoFe2O4 were synthesized through the pyrolysis of hybrid metal nitrates within the pores of two kinds of mesoporous silica, SBA-15 and KIT-6, respectively. Impregnation process, mixture ratio of templates and precursors and other factors that may affect the structure of the product were investigated; samples with a large specific surface area (as high as 155.7 m2/g for the sample templated by SBA-15) and high crystallinity were obtained under optimized conditions, via two times of impregnation according to the mass ratio of precursors/templates X=3; TG-DTA and other characterization method revealed the important part that the silica templates played in the formation of cobalt ferrite phase; magnetic test revealed good magnetic properties of the mesoporous ferrite samples with a rather low coercitivity due to the presence of a prominent proportion of superparamagnetic particles.Secondly, molten salt has been reported to be an excellent media to prepare large crystals with special morphology. Via the molten salt synthesis (MSS) route, well defined octahedral CoFe2O4 crystals with the side length of about 0.5~1.5μm were obtained in a series of molten salt systems, using CoFe2O4 nano particles pre-synthesized through the hydrothermal process as the precursor. It was found that keeping the reaction temperature at 1000 oC for 5h and with a mass ratio of R=5 were the optimal conditions to prepare uniform octahedral ferrite crystals in NaCl/KCl system; furthermore, there were great changes in magnetic and wave-absorbing properties of the samples after molten salt growth, comparing with the precursor.
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