The preparation of magnetic nanoparticles based on cobalt ferrite or magnetite
Priprava magnetnih nanodelcev na osnovi kobaltovega ferita ali magnetita

english

2014

volume 48, issue 2

cobalt ferrite   magnetite    superparamagnetic nanoparticles   co-precipitation    magnetic fluids

Inštitut za kovinske materiale in tehnologije
(Obvezni izvod spletne publikacije)

Cobalt ferrite and magnetite nanoparticles are superparamagnetic materials. Stable suspensions of superparamagnetic nanoparticles are magnetic fluids. Stable magnetic fluids are prepared by the addition of surfactants to supporting polar or nonpolar media. We have studied the preparation of magnetic nanoparticles based on cobalt ferrite or magnetite, and stabilized the obtained product in an aqueous suspension. We found the optimal co-precipitation time for cobalt ferrite at 90 °C to be 2 h. Under such conditions the product exhibited the lowest amount of amorphous phase (46.2 %), average particle diameter 10.2 nm and a relatively high proportion of agglomerated particles (30 %). The product is therefore destabilized in an aqueous solution of polyvinylpyrrolidone K. The optimal co-precipitation time for magnetite at 90 °C is 30 min. After 30 min the product has no amorphous phase, average particle diameter is 6.8 nm and the proportion of agglomerated particles is low (3 %). The product is poorly stabilized because the proportion of agglomerated particles increases when the magnetite is re-dispersed in an aqueous solution of polyvinylpyrrolidone K. Magnetite prepared with the Massart method has a small amount of amorphous phase (4 %), average particle diameter is 6 nm and a low proportion of agglomerated particles (4.5 %) and is therefore well stabilized in an aqueous solution of polyvinylpyrrolidone K.

06.11.2015