Comparison of the Change of Acoustic Attenuation and Anisotropy in Magnetic Fluids Based on Transformer Oils

J. Kúdelčíka, Š. Hardoňa, P. Burya, M. Timkob, P. Kopčanskýb aDepartment of Physics, Faculty of Electrical Engineering and Information Technology, University of Žilina, Univerzitná 1, 010 26 Žilina, Slovakia bInstitute of Experimental Physics, SAS, Watsonova 47, 040 01 Košice, Slovakia

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In the application of a magnetic field to a magnetic fluid, magnetic nanoparticles are created with various structures. In this contribution, we compare the structural changes in three types of transformer oil-based (TECHNOL, MOGUL, and MOL) magnetic fluids upon different developments of magnetic fields and temperatures by the acoustic spectroscopy. The change of the acoustic attenuation was slow (>10 min) or fast (<4 min) depending on the step change of the magnetic field. After switching off the magnetic field, a fast decrease of the acoustic attenuation was observed only for MOL-based magnetic fluid. For linear changes of the magnetic field, the acoustic attenuation increased in steps and a hysteresis effect was observed. The effect of anisotropy of the acoustic attenuation was observed and analysed.

DOI:10.12693/APhysPolA.137.936 topics: magnetic nanoparticles, transformer oil, acoustic attenuation