Electronic relaxation time in silver chalcogenides

The electronic relaxation time in silver chalcogenides - typical ionic-electronic conductors - is investigated using a continuum model. The contributions of longitudinal collective modes to the inverse relaxation time are calculated. It is found that in these materials the aperiodic modes, the diffusion mode and the over-damped acoustic phonon modes, play the major role in the electronic scattering processes and the effects of the periodic modes, the damped acoustic and optical phonon modes, are trivial, in contrast to the cases in ordinary polar crystalline solids.