Magnetic Properties of Stable Dispersions of Subdomain Magnetite Particles

Stable colloidal dispersions of subdomain-size magnetic particles have been prepared that retain their liquid characteristics in the presence of a magnetic field. Magnetization versus applied field curves were obtained as a function of particle size and volumetric solids concentration for magnetite dispersions in a wide variety of carrier liquids. The magnetic properties of these colloidal dispersions have been corrolated by superparamagnetic theory in terms of the size distribution of the suspended particles and their volumetric concentration, correcting for the formation of a nonmagnetic surface mantle one-unit-cell thick.