| Abstract
| - The dielectric behavior of suspensions of polystyrene/zinc oxide (PS/ZnO) composite particles in aqueous and electrolyte solution have been investigated by dielectric relaxation spectroscopy (DRS) in the frequency range from 40 Hz to 110 MHz. Two relaxations were confirmed by means of the logarithmic derivative method in this frequency range, which turned out to be very effective in resolving overlapped relaxations. The effects of volume fraction and the electrolyte concentration of composite particles on the dielectric response of suspensions were examined in detail, respectively. According to dielectric analysis, we found an abnormal and significative phenomenon, namely, special dielectric increments, where ∂εl = (εl − εm)/φ and ∂εh = (εm − εh)/φ denoting the low- and high-frequency relaxation amplitude of suspensions of PS/ZnO particles per unit volume, respectively, were increasing with the enhancement of volume fraction φ. On the basis of the combination of studying the dielectric parameters by fitting data with the Cole−Cole equations and phase parameters calculated by Hanai method, we proposed that except for the two distinct relaxations, the low- and high-frequency relaxations which are occurred at lower kilohertz and higher megahertz frequencies, respectively, suspensions exhibit an additional dielectric relaxation over the megahertz frequency range, here named “the third relaxation”, due to the polarization of internal double layer of the thin layer of semiconducting ZnO when an external field is applied.
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