Study of structural arrangement in ferrofluid by dielectric and acoustic spectroscopy

In the paper two methods of investigation of ferrofluid in magnetic and electric fields were used, namely the acoustic and the dielectric spectroscopy. The measurements were done at temperature 15 °C. The effect of structural changes in ferrofluid upon the effect of a magnetic field by the acoustic spectroscopy was studied. At jump change of the magnetic field to 100, 200 and 300 mT a continuous change of the acoustic attenuation caused by an aggregation of magnetic nanoparticles to new structures was observed. The changes in dielectric parameters and structural arrangement of magnetic nanoparticles in ferrofluid upon the effect of magnetic and electric fields have been studied by the dielectric spectroscopy, too. The frequency dependence of dissipation factor was measured by a capacitance method within the frequency range from 1 mHz to 10 kHz at the application of a magnetic and an electric fields. The magneto-dielectric effect was also observed.