Magneto-induced anisotropy in magnetic colloids of superparamagnetic magnetite nanoparticles in an external magnetic field.

Here we report a study of chain formation and the magnetic anisotropy induced by them in suspensions of slightly anisotropic FeO nanoparticles in water and in aqueous VO suspensions. An investigation into the magnetization of the fluid and frozen suspensions, the application of dynamic light scattering techniques and the observation of the magnetic anisotropy in the frozen magnetically aligned samples allowed us to confirm the existence of chains of FeO in both suspensions. Our study shows that the magneto-induced anisotropy appearing in magnetic fields in colloids with FeO particles is mainly due to many particle (chain) magneto-induced anisotropy, but not due to single particle magneto-induced anisotropy connected with particle shape anisotropy.

Excess nonspecific Coulomb ion adsorption at the metal electrode/electrolyte solution interface: role of the surface layer.

Excess ion adsorption gamma induced by the polarization image forces in the system of a metal electrode/symmetric electrolyte solution separated by an insulating interlayer has been calculated. The adopted theoretical scheme involves the Coulomb Green's function in a three-layer system with sharp interfaces and specular reflection at them. The influence of the spatial dispersion of the dielectric permittivities epsilon(i)(k) in all the three media on the image force energy W(im) and the adsorption gamma has been analyzed, where k is the wave vector.