Ion dynamics in organic-inorganic composite superionic conductor glasses

Ionic conductivity of organic-inorganic composite superionic conductor glasses composed of AgI and alkylammoniumiodides is measured as a function of frequency, temperature and composition. A clear transition from insulator to superionic conductor is confirmed at the volume fraction of AgI is about 35 %. The dc component of the conductivity is fitted to the σ∼(- _c)^μ with _c=0.36, μ=2.5 for the present data. Near the percolation threshold, a power-law type frequency dependence of ωⁿ (n∼0.67) is seen in mid frequency and ω^1.0 at higher frequency corresponding to the constant loss region power-law is observed. The activation energies and preexponential factors derived from the temperature dependence increase from 0.3 to 0.7 eV approaching to the threshold. From these results, the ion dynamics in these glasses can be explained by the static site percolation theory at first approximation, but require the consideration on the chemical bond variation between the Ag and I modified by the organic ions.