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The Magnetic and Colloidal Properties of CoFe2O4 Nanoparticles Synthesized by Co-precipitation

Sašo Gyergyek, Miha Drofenik, Darko Makovec

Abstract


Magnetic CoFe2O4 nanoparticles were synthesized by co-precipitation at 80 oC. This co-precipitation was achieved by the rapid addition of a strong base to an aqueous solution of cations. The investigation of the samples that were quenched at different times after the addition of the base, using transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDXS) and X-ray powder diffractometry, revealed the formation of a Co-deficient amorphous phase and Co(OH)2, which rapidly reacted to form small CoFe2O4 nanoparticles. The nanoparticles grew with the time of aging at elevated temperature. The colloidal suspensions of the nanoparticles were prepared in both an aqueous medium and in a non-polar organic medium, with the adsorption of citric acid and ricinoleic acid on the nanoparticles, respectively. The measurements of the room-temperature magnetization revealed the ferrimagnetic state of the CoFe2O4 nanoparticles, while their suspensions displayed superparamagnetic behaviour.


Keywords


Cobalt ferrite; nanoparticles; co-precipitation; colloidal suspensions; magnetic properties

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