Δ ∝ ) and entropy (i.e. Δ ∝ ln ( )). This relation has been derived before using transition state theory and the multi-excitation entropy model. Specifically, it is believed that the inverse slope of the Meyer-Neldel plot is related to the energy of the vibrational modes that participate in ionic conduction, as well as a characteristic number of vibrations. However, a consistent definition of these quantities has been lacking. Nevertheless, an inverse slope of ~37 meV is in agreement with those reported for other superionic conductors. In comparison to the energy range of the calculated phonon density of states it is unclear what this value really represents, except that the vibrational states of the Ag + ions do not change significantly through the substitution series, and that the overall vibrational properties are not significantly affected by the composition. By novel considerations of the phonon entropy (Supplemental Note 6), we show that using an average frequency of Ag + vibrational modes (~2 THz) in the evaluation of the Meyer-Neldel slope coincides with a characteristic number of vibrations (~4.6 phonons) nearby the value expected (~3.1 phonons) from Bose-Einstein statistics at room temperature.