Relation between conductance and dielectric relaxation time

[tworitdash]

I am studying about dielectric materials and their relaxation properties. There are several ranges of electromagnetic frequencies where different material show different kinds of resonance starting from molecular to atomic motions. Based on the frequency dependence of the imaginary part of the permittivity, the resonance frequencies are determined.

For example, as the conductivity of saline water increases with salinity, the imaginary part of permittivity increases with increasing salinity at lower frequencies as the additional term in the imaginary part due to conductivity is inversely proportional to the frequency $\sigma/\omega$ . However, I see a decline in the real part of the permittivity as well if I observe more salinity. The real part depends on the static and optical permittivities and the relaxation time. Does conductivity have an impact on one of these at least?

$$ \epsilon_{real} = \epsilon_\inf + \frac{(\chi_{stat} - \epsilon_\inf)}{1 + (\omega * \tau) ^ 2}$$

 

[Svein]

For example, as the conductivity of saline water increases with salinity,

You are aware of the "threshold"? At a potential difference below ≈1V between the water and the electrodes, the conductivity decreases fast...