Electrical conduction in a transformer oil-based magnetic nanofluid under a DC electric field.

Abstract In this paper, we report on the experimental study of the direct current electrical conduction in a magnetic nanofluid based on transformer oil and iron oxide nanoparticles stabilized with oleic acid. We present the current–voltage characteristics of the pure transformer oil and the magnetic nanofluid with various particle volume fractions. From the Ohmic region, we calculate the electrical conductivity values and confirm the effect of increasing conductivity with increasing particle volume fraction. A few sources of space charge have been taken into account, among which the ion impurities play the key role. It was found that the current–voltage characteristics exhibit the inverse hysteresis-like behavior. Then, we focus on the magnetic field influence on the hysteresis behavior of a selected sample. The external magnetic field was applied in both, parallel and perpendicular configuration in regard to the electric field direction. It is shown that the magnetic field acting on the magnetic nanofluid in the perpendicular configuration results in the remarkable thinning of the current–voltage inverse hysteresis loop.