Preparation and magneto-optical behavior of ferrofluids with anisometric particles

Abstract

Nanoparticles of barium hexaferrite have been synthesized by hydrothermal method. Copper and cobalt ferrite nanoparticles have been prepared via a novel coprecipitation technique. The particles were characterized by scanning electron microscopy, transmission electron microscopy, dynamic light scattering, magnetic granulometry, wide angle x-ray diffraction, small angle x-ray scattering, small angle neutron scattering. For preparation of the ferrofluids, relatively large nanoplates have been stabilized by a double layer. A stabilization method has been developed and the stable ferrofluids with large particles have been obtained. Magneto-optical effects in the ferrofluids containing both spherical and anisometric ferrite nanoparticles have been studied. The ferrofluids with relatively large nanoplates—61 and 51 nm—have been found to be efficient magneto-optical media. Magneto-optical response in these media has been shown to be one or two orders of magnitude higher, than the one in the colloids with particle size about 10 nm. Characteristic frequencies and aggregate sizes have been determined using experimental data.

Dynamic Susceptibility of Ferrofluids: The Numerical Algorithm for the Inverse Problem of Magnetic Granulometry

“…Traditionally the researchers try to characterize the nanoparticles with their sizes [10][11][12]. However, here one needs to assume some shape for a nanoparticle and to make some approximations concerning the nanoparticle internal structure.…”