The available sites for ions in a typical disordered ionic conductor were determined. For this purpose a straightforward algorithm was devised which, via cluster analysis, deduced these sites from long-term ionic trajectories below the glass transition. This was exemplified for a lithium silicate glass (Li2O)x(SiO2)1–x for x = 0.5 and x = 0.1. It was found that, for both concentrations, the number of sites was only slightly higher than the number of ions. This result suggested a theoretical description of the dynamics in terms of mobile vacancies as being the most appropriate. Furthermore, identification of the ionic sites permitted the obtention of detailed characteristics of the ionic motion, such as a quantification of correlated forward-backward jumps.

Complete Identification of Alkali Sites in Ion Conducting Lithium Silicate Glasses - a Computer Study of Ion Dynamics. H.Lammert, M.Kunow, A.Heuer: Physical Review Letters, 2003, 90[21], 215901 (3pp)