The nature of conduction pathways in mixed alkali phosphate glasses

In this paper we discuss the nature of the ion conduction pathways in LixRb1-xPO3 glasses. Our investigations are based on a bond valence analysis of reverse Monte Carlo (RMC) produced structural models in quantitative agreement with neutron and X-ray diffraction data. In a previous letter [11] we have shown that this approach enables us to reproduce and understand the mixed alkali effect (MAE) directly from the structural models. The results have shown that the drastic drop of the conductivity for an intermediate composition (x approximate to 0.5) is mainly caused due to the blocking by immobile unlike cations, which is highly effective since the two types of alkali ions are randomly mixed and have distinctly different conduction pathways of low dimensionality. Here, we explore the local dimensionality of the pathways and discuss its implications for the network of pathways and the related ionic conductivity.