Transient ionic current and impedance spectroscopic techniques were used to measure Ag+ ion mobility and conductivity in the  and  phases. The mobile ion concentration was then calculated by using the mobility and conductivity data. All 3 quantities were found to exhibit thermally activated behavior in both phases. The energies of migration and formation of Ag ions were estimated to be 0.14 and 0.15eV, respectively, in the  phase. The corresponding values for the  phase were 0.05 and 0.006eV. The extremely low formation energy for the  phase suggested that a negligibly small number of mobile ions was thermally added to the large number of mobile ions which already existed in this phase. On the basis of the results, it was concluded that the large increase in the conductivity of -AgI was due mainly to an abrupt increase in the mobile ion concentration. The contribution of ionic mobility to the total conductivity was small.

R.C.Agrawal, K.Kathal, R.K.Gupta: Solid State Ionics, 1994, 74[3-4], 137-40