Ag K-edge EXAFS OF AgI–alkylammonium iodide glasses

Abstract

Ag K-edge EXAFS of organic–inorganic mixed ionic conductor glasses of AgI–alkylammonium iodides were measured by varying their compositions. Although their conductivity varies from superionic conductors to insulators through a percolation threshold, no significant change was seen in local structure around mobile Ag + ions. From a cumulant analysis of the EXAFS data, the nearest neighbor distance between Ag + and I − is estimated to be 2.79 Å and the coordination number is 4.5±0.5 irrespective of the compositions. From these results, it is concluded that the transition from superionic conductor to insulator is not due to the change in local structures but by their intermediate range structure such as connectivity of percolation networks.