Frequency-dependent loss tangent and power factor of magnetic fluids

Measurement of the frequency-dependent loss tangent, tan delta, and power factor, sin delta, over the frequency range 20 MHz-6 GHz, of four magnetic fluids, namely fluids 1, 2, 3 and 4, with particle packing fractions of 0.18, 0.09, 0.036 and 0.018 are reported. The loss parameters are presented in terms of the complex susceptibility components, chi(omega) = chi'(omega) - i chi "(omega), of the samples and it is shown that in the case of fluid 4 the frequency-dependent profiles of chi ", tan delta and sin delta are almost identical. (C) 2001 Elsevier Science B.V. All rights reserved.