Influence of Temperature on the Magneto-Dielectrics Effect of Oil-Based Ferrofluid

The effect of temperature on the magneto-dielectrics behavior was studied by dielectric spectroscopy in the transformer oil-based ferrofluid with magnetic nanoparticles upon the effect of an external magnetic field. The frequency dependence of complex permittivity and dissipation factor were measured within the frequency range from 1 mHz to 10 kHz at different temperatures by a capacitance method. The dielectrics parameters were measured as a function of the external magnetic field in the range of 0-200 mT, parallel to the direction of the electric field as a function of temperature in the range of 15-35 degrees C. The interaction between magnetic field and magnetic moments of nanoparticles led to the aggregation of magnetic nanoparticles to new structures which had influence on dielectric parameters. The dependence of these parameters at constant magnetic field on angle between the direction of the electric and magnetic fields (anisotropy) has been measured, too.