Temperature Effect on Anisotropy of Acoustic Attenuation in Magnetic Fluids Based on Transformer Oil

Abstract

Magnetic nanoparticles in magnetic fluids under the effect of magnetic field create structures, which are not arranged uniformly. These structures have various shapes dependent on the intensity and duration of applied magnetic field. In the case of such structures the anisotropy of acoustic attenuation can be observed. The effect of temperature on this process was studied by acoustic spectroscopy in transformer oil-based magnetic fluids. Taketomi theory that assumes existence of spherical clusters was used. These clusters form long chains, aligned in magnetic field direction. The cluster radius, the number density of the colloidal nanoparticles as well as other parameters of magnetic nanoparticles were determined from experimental results. These data allowed to draw conclusions about the changes in the parameters describing the structures of magnetic nanoparticles in the investigated magnetic fluid caused by different temperatures.