Complete ionic conductivity spectra and quasi-elastic and inelastic neutron scattering spectra were obtained at various temperatures. High-amplitude vibrational movements, mainly of the Ag ions, contributed to both types of spectra. In particular, a conductivity maximum at about 500GHz reflected the oscillations of individual Ag ions along <111> directions. The microwave and mm-wave conductivities were dominated by a thermally activated Debye-type relaxation process. This effect could be consistently explained by the frequent hopping of Ag ions from normal octahedral lattice sites into tetrahedral interstitial sites and back again. That is, by the frequent creation and recombination of Frenkel pairs. The effect was also responsible for the existence of thermally activated quasi-elastic components in the neutron scattering spectra. The width of the coherent quasi-elastic scattering showed that the to-and-fro hopping of a Ag ion was accompanied by the rapid correlated movement of ions in its immediate vicinity.

K.Funke, T.Lauxtermann, D.Wilmer, S.M.Bennington: Zeitschrift für Naturforschung, 1995, 50a[6], 509-20