The conduction of Ag ions along the c-axis of single crystals of the  phase was studied by means of impedance spectroscopy at temperatures ranging from 26 to 360K, and frequencies ranging from 0.1 to 150kHz. The Ag ion conduction was characterized by frequency-independent and frequency-dependent processes. The frequency-dependent part obeyed a power law. Anomalies were observed, at about 40 and 200K, in the real part of the complex conductivity and at about 200K in the imaginary part. It was shown that the frequency-dependent complex conductivity, at frequencies below about 160K and above 220K, could be explained in terms of Bernasconi’s random barrier model. Ordering of Frenkel defects was suggested to occur at temperatures above about 220K.

S.Yoshikado, H.Goto, T.Murata, Y.Azuma, I.Taniguchi, Y.Ito, B.E.Mellander: Solid State Ionics, 1995, 79, 124-8