Polarizing Field and Particle Concentration Dependence of the Magnetic Loss Power in Ferrofluids Available to Purchase

The frequency (f) and polarizing field (H) dependence of the complex magnetic permeability $μ(f,H) = μ′(f,H)−iμ″(f,H),$ of different magnetic fluid samples, over the range $100 MHz$ to $6 GHz$ and 0 to $102.4 kA/m,$ respectively, were analyzed. Starting from an initial magnetic fluid sample (sample A) with magnetite particles dispersed in kerosene and stabilized with oleic acid, having particle concentration $n = 19.16⋅1022 m−3,$ three samples were obtained by successive dilution with kerosene (with a dilution ratio 2:3) (samples A1, A2, and A3). Based on the complex magnetic permeability measurements of each sample, and for each field value, values of the specific magnetic loss power were obtained. We have also studied the dependence on particle concentration of the magnetic loss power, both in zero polarizing field and in the presence of the polarizing field.