Generation of Fe 3O 4 Nanoparticle Aggregates in a Ferrofluid Driven by External Electric Field
J. Kurimskýa, M. Rajňáka,b, R. Cimbala a, K. Paulovičová b, M. Timko b, P. Kopčanský b, M. Kolcun a, M. Kosterec a and L. Kruželák a
aFaculty of Electrical Engineering and Informatics, Technical University of Košice, Letná 9, 041 54 Košice, Slovakia
bInstitute of Experimental Physics, SAS, Watsonova 47, 040 01 Košice, Slovakia
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In the paper the experimental study of magnetic nanoparticle aggregation in a transformer oil based ferrofluid driven by an external electric field is reported. The studied ferrofluid was composed of the magnetite nanoparticles, oleic acid surfactant, and transformer oil. Generally, it is considered that superparamagnetic nanoparticles do not interact in the absence of external magnetic field. In the paper we present an experimental observation of the particle assembly formation in a direct current external electric field by optical microscopy. During the observation no external magnetic field was applied. A diluted low-polarity ferrofluid drop on a glass surface was exposed to the external static inhomogeneous electric field. It is assumed that induced dipole-dipole interaction and subsequent dielectrophoretic motion give rise to the electrohydrodynamic flow in the fluid after a certain time period. As a result, a visible particle chain was formed at the drop electrical equator. This demonstration is expected to contribute to the understanding of the streamer formation and electrical breakdown in transformer oil based ferrofluids.

DOI: 10.12693/APhysPolA.131.907
PACS numbers: 47.57.J-, 47.65.Cb, 77.22.Jp, 77.22.Ch, 82.70.Dd