Impedance spectroscopy studies of K2SO4 in the intermediate temperature regime

Impedance spectroscopy measurements of K2SO4 have been carried out from 5 Hz to 13 MHz over the temperature range 403-782 °C. The plots of corrected imaginary part of permittivity, ε″, and its real part ε′ vs. frequency clearly show a new dielectric relaxation around fmax=1.4×104 Hz at 403 °C, which shifts to higher frequencies (∼1 MHz) as the temperatures increases. The fmax (calculated from the peak position of ε″) vs. reciprocal T shows an activated relaxation process over the temperature range 403-600 °C with activation energy Ea=1.02 eV, which is close to that derived from the dc-conductivity, Eσ=1.15 eV. We suggest that the observed dielectric relaxation could be produced by the K+ jump and SO4− reorientation that cause distortion and change the local lattice polarizability inducing dipoles like KSO4−.