Nanosized ferrite particles - Preparation, characterization, and magnetic properties

Cobalt and iron (II) dodecyl sulfate, Co(DS)(2) and Fe(DS)(2), are used to make CoFe2O4 and Fe3O4 nanosized magnetic particles. The size of the particles is controlled by the surfactant concentration. It is possible to obtain the particles either suspended in the solvent forming a ferrofluid or as a dry powder. The average size of the particles varies from 2 to 5 nm for CoFe2O4 and from 3.7 to 11.6 nm for Fe3O4. The magnetic studies performed on particles of various size confirmed superparamagnetic behavior in each case. The saturation magnetization decreases with particle size and can be explained in terms of an increase in the noncollinear structure at the interface.