ACTA

Small Angle X-ray Scattering Study of Magnetic Nanofluid Exposed to an Electric Field

M. Rajnak^{a, b}, V.M. Garamus^c, M. Timko^a, P. Kopcansky^a, K. Paulovicova^a, J. Kurimsky^b, B. Dolnik^b, R. Cimbala^b
^aInstitute of Experimental Physics, SAS, Watsonova 47, 04001 Košice, Slovakia
^bFaculty of Electrical Engineering and Informatics, Technical University of Košice, Letná 9, 04200 Košice, Slovakia
^cHelmholtz-Zentrum Geesthacht, Centre for Materials and Coastal Research, Max-Planck-Str., 21502 Geesthacht, Germany

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We report on the investigation of a transformer oil-based magnetic nanofluid exposed to an electric field by means of synchrotron small angle X-ray scattering. Two types of small angle X-ray scattering experiments were carried out. In the first one, the electric field up to 6 kV/cm was generated in the nanofluid between two immersed electrodes. The other experiment focused on the nanofluid in an external electric field up to 10 kV/cm, when the electrodes were not in a direct electrical contact with the nanofluid. In the available range (0.02-4.5 nm^-1) of scattering vector q, the non-contact mode has no effect on the scattering intensity. The contact mode yielded noticeable low-q intensity variations. In comparison to small angle neutron scattering, the small angle X-ray scattering study did not prove the proportional increase in the low q scattering intensity with increasing electric field, but rather stochastic variations. The observed intensity variations reflect the local structural nanofluid changes caused by the induced electrohydrodynamics. The electrical conductivity and relaxation processes are pointed out as favorable conditions for electrohydrodynamics in the magnetic nanofluid.

DOI:10.12693/APhysPolA.137.942
topics: magnetic nanofluid, small angle X-ray scattering (SAXS), electric field