Heterogeneity, multi-fractality and cooperativity in the ionically conducting glasses

Heterogeneity, multi-fractality and cooperativity coming from the complex many-ion dynamics in ionically conducting glasses and the dynamical potential surface are the key features for a fall understanding of the dynamics of die ions. We have examined these features of Li ions in the lithium metasilicate (Li2SiO3) glass by molecular dynamics simulations. The dynamical potential surface, obtained by the accumulated positions of Li ions during a MD run, has been analyzed by using singularity spectra to have a multi-fractal character. Mixing of localized ion and diffusive ion dynamics is one of the causes of the multi-fractality observed. Single and cooperative motions of Li ions on the surface have been examined respectively by the singular spectrum analysis (SSA) and the multi-channel singular spectrum analysis (M-SSA). Phase-space plots using de-noised data obtained by SSA show the deterministic character of the dynamics of ions, localized and diffusive.