Complete identification of alkali sites in ion conducting lithium silicate glasses: a computer study of ion dynamics

Abstract

The available sites for ions in a typical disordered ionic conductor are determined. For this purpose we devised a straightforward algorithm which via cluster analysis identifies these sites from long time ionic trajectories below the glass transition. This is exemplified for a lithium silicate glass (Li_2O)_x (SiO_2)_(1-x) for x = 0.5 and x = 0.1. We find for both concentrations that the number of sites is only slightly bigger than the number of ions. This result suggests a theoretical description of the dynamics in terms of mobile vacancies as most appropriate. Furthermore identification of the ionic sites allows one to obtain detailed characteristics of the ionic motion, e.g. quantification of correlated forward-backward jumps.

4 pages, 4 figures, revtex4, as published in PRL, with corrections from proofs including some numerical values

References in corpus (3)

• Channel diffusion of sodium in a silicate glass
• The dynamics of sodium in sodium disilicate: Channel relaxation and sodium diffusion
• Characterization of the complex ion dynamics in lithium silicate glasses via computer simulations

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• A complete identification of lithium sites in a model of LiPO${}_3$ glass: effects of the local structure and energy landscape on ionic jump dynamics
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• Coupling of ion and network dynamics in lithium silicate glasses: a computer study
• Physical mechanisms of nonlinear conductivity: a model analysis
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