Site trapping and commensurability effects in framework solid electrolytes

We have performed Langevin dynamics calculations on a one-dimensional model for framework materials, focusing on the conductivity of interacting mobile ions in the presence of Coulombic traps. We observe several interesting phenomena, arising from competition among the three potentials (lattice, ion-ion, ion-trap). Findings of interest include: 1. Generally, the compensator will indeed trap a sufficient number of mobile ions to balance its charge. These ions can exchange, but they are quite well localized by the trap. 2. For incommensurate mobile-ion concentrations, the overall DC conductivity is decreased. 3. For commensurate concentrations, the DC conductivity can actually increase, as the trapping renders the remaining mobile-ion array effectively incommensurate.