Ionic conduction and relaxation in KSn2F5 fluoride ion conductor

Ionic conductivity of the superionic polycrystalline KSn2F5 material is investigated by impedance spectroscopy in a wide temperature range. An abrupt increase of the conductivity is observed at 428 K due to the superionic phase transition. The activation energy of conduction decreases from 0.53 to 0.24 eV after the phase transition. The frequency dependence of the complex conductivity, electric modulus and dielectric permittivity spectra are analyzed by the UDR and KWW approaches, and a comparison between the parameters derived from the two approaches has been discussed