Resumen de Dielectric constant, dielectric loss, ac conductivity of Polystyrene - Ni composites
The AC electrical properties of PS-Ni composites with different nickel (Ni) concentration are investigated. The AC electrical conductivity, loss factor and dielectric constant of these composites have been studied at frequency range from 100 Hz to 10 MHz The effects of nickel content, of the frequency of the applied electrical field, and of the temperature on the above properties are considered. For the composites of Ni content below the threshold value φ[subíndice c], the dielectric constant E and the AC conductivity slightly in crease with Ni content and with temperature. Both vary as a power law of ω, such as ε ∞ω[superíndice -Y] and σ [subíndice AC]∞ω [superíndice x] near φ[subíndice c] The two exponents X and Y were found to satisfy the percolating relation X + Y =1 and to be temperature dependent. The dielectric loss is slightly increasing with Ni content and with temperature, and shows some oscillatory behavior in the frequency range of interest. For the composite of Ni content equal to or above φ[subíndice c] the values of dielectric constant, dielectric loss and AC conductivity are very large and slightly decrease with increasing temperature. Moreover, the dielectric constant and AC conductivity have nearly constant values at low and intermediate frequency range, but decrease sharply at high frequencies. The dielectric loss is decreasing with the frequency and there is no indication for any relaxation peak.
