Cross conductivity in silver chalcogenides

The electronic and ionic cross conductivity by a continuum model in silver chalcogenides is studied theoretically. It is shown that the ratio of the ionic conductivity to the cross conductivity is given by the simple ratio of the number density multiplied by the valence number of diffusing particles. This relation explains the experimental results qualitatively, while the upper value of the ratio of conductivities in this model is smaller than the experimental values. This point is discussed by considering the motion of mobile ions from the viewpoint of a hopping model with an overlapping of potentials affecting the electrons.