Characterization of dielectric dispersion and ionic conduction behaviour of acetonitrile at low frequencies

Abstract

The complex dielectric function, ionic conductivity and impedance behaviour of acetonitrile have been investigated over the frequency range 20 Hz-1 MHz and at the temperatures 15, 30 and 45°C. The real part of complex dielectric function increases significantly with the decrease of frequency below 100 kHz, confirms the contribution of electrode polarization effect in the dielectric properties of acetonitrile at low frequencies. The real part of alternating current conductivity shows the direct current ionic conductivity plateau in the frequency range 1 kHz-1 MHz. The complex impedance plane plots have been used to separate the electrode polarization effect from the bulk acetonitrile properties. The values of temperature dependence electrode polarization relaxation time have been determined from the frequency which corresponds to the peaks observed in the dielectric loss tangent spectra. The activation energies of relaxation time, conductivity and viscosity have been evaluated from their Arrhenius plots, and discussed in relation to the ionic conduction mechanism in the pure liquid state of acetonitrile.