INTERFACE AND BULK RELAXATION IN SOLID IONIC CONDUCTORS

The frequency dependent response of solid ionic conductors (solid electrolytes) to a small amplitude ac voltage applied through dc blocking metal contacts is due to polarization from two sources: (i) charge accumulation at the metal-electrolyte interfaces and (ii) displacement of bound charges and defects within the electrolyte. These give rise to a characteristic constant phase angle behavior of the interface impedance and bulk permittivity above the loss peak. The interface impedance is attributed to ion diffusion in screened regions near the electrode surface while the permittivity of the electrolyte is modeled using a temperature dependent distribution of activation energies for ion hopping in double potential wells.