Ion dynamics in this 2-dimensional fluoride-ion conductor were studied by using 19F nuclear magnetic resonance and impedance spectroscopy. The electrical relaxation behavior was presented in the conductivity and electric modulus formalisms. The direct-current conductivity and the hopping frequency of mobile ions, and their respective activation energies, were estimated from an analysis of the conductivity spectra by using the Almond–West formalism. It was found that the activation energies for conduction and ion-hopping were almost identical: with values of 0.53 and 0.54eV, respectively. This suggested that the concentration of charge carriers was independent of temperature. The Roling scaling approach, to conductivity spectra, was used to obtain some insight into the temperature-dependence of the relaxation mechanism. The scaling law successfully collapsed the conductivity spectra into a single curve; thus indicating a temperature-independent relaxation mechanism. Chemical exchange simulation of the 19F nuclear magnetic resonance spectra was also used. A discrepancy between the values of the activation energies, as deduced from electrical and nuclear magnetic resonance experiments, was explained in terms of the Ngai coupling model.

Fluoride Ion Dynamics and Relaxation in KSn2F5 Studied by 19F Nuclear Magnetic Resonance and Impedance Spectroscopy. M.M.Ahmad, M.A.Hefni, A.H.Moharram, G.M.Shurit, K.Yamada, T.Okuda: Journal of Physics - Condensed Matter, 2003, 15[31], 5341-52