Electrical ionic conductivity and electronic spectra of superionic KAg <inf>4</inf>I<inf>5</inf> films

Electrical ionic conductivity studies in superionic KAg4I 5 thin films show good agreement with the best bulk studies. The activation energy for Ag+ ion conduction and the free-ion-like parameters such as mean free path and the lifetime in the excited state have been deduced from the conductivity plots. Studies on the compositional dependence of the electrical conductivity of the KI-AgI system reveal that the conductivity reaches a value of 0.25 Omega -1 cm-1 for films with 80 mole.% of AgI. Electronic spectra of these films show a well defined exciton state 3750 AA at 300K. A forbidden internal transition in the Ag+ ion has been observed at 4250 AA. The existence of silver colloids in the films has been revealed through a broad band around 5000 AA.