Temperature Dependence of a Dielectric Relaxation in Weakly Polar Ferrofluids
M. Rajňáka,b, J. Kurimský b, B. Dolník b, R. Cimbala b, K. Paulovičová a, P. Kopčanský a and M. Timko a
aInstitute of Experimental Physics, SAS, Watsonova 47, 040 01 Košice, Slovakia
bFaculty of Electrical Engineering and Informatics, Technical University of Košice, Letná 9, 042 00 Košice, Slovakia
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In this paper, we report on the temperature dependent broadband dielectric response of a ferrofluid based on transformer oil and magnetite nanoparticles covered with oleic acid molecules. For that purpose the method of dielectric spectroscopy has been chosen in the frequency range from 20 Hz up to 100 kHz. The experiments were carried out on thin film ferrofluid samples confined in a glass plate capacitor containing indium tin oxide (ITO) plate electrodes. The obtained complex permittivity spectrum shows a pronounced dielectric dispersion in the low frequency range. Taking into account the ferrofluid composition we associate this relaxation with ion impurity polarization at the nanoparticle-oil interface. The strong temperature dependence of the relaxation process has been found when conducting the experiments in the temperature range from 298 K to 358 K. The relaxation time of the revealed process exhibits a typical Arrhenius behavior. Based on the conducted experiments and analysis, we propose some reasonable practical applications of the studied ferrofluid in the field of electrical engineering.

DOI: 10.12693/APhysPolA.131.943
PACS numbers: 47.65.Cb, 77.22.Ch, 77.22.Gm, 82.70.Dd