The ionic conductivity and the dielectric relaxation properties of Na2SO4 were investigated by means of impedance spectroscopy measurements over wide ranges of frequency and temperature. The frequency dependent impedance data were modeled by appropriate equivalent circuit representing the bulk and grain boundary properties of the sample. Phase transition temperatures and the activation energies of conduction in different phases were determined from the temperature dependence of the dc conductivity. Dielectric relaxation was studied using the complex electric modulus and permittivity formalisms. From the electric modulus formalism it was concluded that the relaxation mechanism was independent of temperature. The dielectric permittivity spectra were analyzed by the Cole–Cole formula where different parameters were determined.

Ionic Conduction and Dielectric Relaxation in Polycrystalline Na2SO4. M.M.Ahmad: Solid State Ionics, 2006, 177[1-2], 21-8