PREPARATION OF COLLOIDAL FE3O4 ULTRAFINE PARTICLES IN MICROEMULSIONS

The preparation of magnetite particles is reported from the precipitat ion of Fe2+/Fe3+ with NH4OH in several kinds of microemulsions: AOT/n- heptane/water microemulsions and a new non-toxic microemulsion system whose phase behaviour and structure has been recently studied. It is s hown that both the droplet size and the presence of interactions in th e dispersed phase greatly influence the final size of the obtained par ticles. In addition, the size of the particles can. be increased by su ccessive repetition of the reaction inside the droplets of the microem ulsion.