Possibility of using a ferrofluid in its different phases

We report on the dielectric and magnetodielectric effects in the different phases of an ionic ferrofluid made of nanometric particles of manganese ferrite (Fe₂MnO₄) diluted at different volume concentration in carbon tetrachloride (CCl₄) used as carrier liquid. To obtain a fast recording of experimental data we have used an automated spectrometer working in the frequency range 1 mHz-10 MHz and from -200°C up to 50°C. This study shows the presence of three phases (liquid, plastic and solid) for pure CCl₄, these phases remain for the ferrofluid. Our experimental results allow an investigation of homogeneity and stability of these ionic dispersions at different concentrations and phases. Finally, a magnetodielectric anisotropy is observed when a continuous magnetic field (parallel or perpendicular to the electric field) is applied. This anisotropy observed at room temperature remains at very low temperature, in particular in the plastic phases