Electrical conductivity of the AGP513A, a ferromagnetic liquid, measured at frequency range of 0.1–12 MHz

The electrical conductivity of the AGP513A, a ferromagnetic liquid, was studied in the frequency range of 0.1–12 MHz and the temperature range of 20–50 °C. For the frequency up to about 4 MHz, the increase of electrical conductivity was weak. However, above this frequency, a rapid increase in electrical conductivity was observed. Three sub-ranges were distinguished in the loss tangent–frequency relationship. In the first sub-range, up to the frequency of 1 MHz, the increase in the loss tangent was weak. In the second range, i.e. 1–4 MHz, the increase in frequency and temperature did not affect the loss tangent, whereas in the third sub-range above 4 MHz, it increased rapidly. Most probably, the dispersion in the range of 0.1–4 MHz was the effect of aggregating of ferrofluid nanoparticles. Yet, for the frequencies above 4 MHz, the aggregates of nanoparticles disappeared.