Silver ion dynamics in mixed network former glasses: Evidence of correlation with characteristic lengths and network structure

Abstract

We have presented conductivity spectra at different temperatures for mixed network former silver borophosphate glasses. By mapping the conductivity spectra onto time dependence of the mean square displacement of mobile ions in the framework of linear response theory, we have obtained two characteristic lengths of ion dynamics viz characteristic mean square displacement at which crossover from diffusive to subdiffusive ion dynamics and spatial extent of localized motion of mobile silver ions occur. We have shown that the mixed network effect in these glasses is correlated to these characteristic lengths which are strongly influenced by the Coulomb repulsion between the mobile silver ions as well as the interaction between the mobile ions and the glass network.

Polaronic transport in iron phosphate glasses containing HfO2 and CeO2

“…Moving on to the information on length scales that can be obtained from the frequency-dependent conductivity and permittivity spectra, we find that in the literature there are a few methods which describe the estimation of mean-squared localized displacement of ions either from the conductivity spectra 41,[49][50][51] or from the permittivity spectra. 42,49,50,52,53 Here, however, making use of the fact that we have well-defined permittivity plateaus we prefer to estimate the spatial extent of localized displacement in a model-free 47 approach by scaling the experimental permittivity spectra using the Summerfield scaling procedure.…”

Insights from Local Network Structures and Localized Diffusion on the Ease of Lithium Ion Transport in Two Mixed Glass-Former Systems

“…[30][31][32][33][34][35] Additionally, there has been some efforts in extracting relevant length scales (see Appendix A) by analyzing the ionic conductivity and dielectric permittivity spectra in alkali ion based MGF systems. 17,[36][37][38] The main findings on changes in structural units and bonds as a function of relative composition of glass formers in borophosphate glasses containing Li2O or Na2O as network modifiers is that hetero-atomic bonds such as P-O-B are preferred to homo-atomic bonds such as P-O-P and B-O-B, for up to about 30 mol% borate content. This information was made possible by X-Ray Diffraction (XRD) technique and XPS spectroscopy, 27 or by using Raman and magic-angle spinning (MAS) NMR experiments.…”

“…[62][63] If the Haven ratio is assumed to be unity, since this is a hard to determine quantity, what this relation yields is < R 2 ( ) >, the mean-square displacement of the center of charge of the mobile ions. One thus constructs a plot of 〈R 2 ( )〉 versus log(t), and can read off the value of Another length scale which is relevant is the spatial extent of localized diffusion, and is calculated as 〈r 2 (∞)〉 1/2 from scaling of the real part of the permittivity spectra 7,45,46 using the MIGRATION concept; or in a model independent way from an analysis of the permittivity spectra 36,38,62,63 as 〈R 2 (∞)〉 1/2 . This length scale gives information on the nature of the localized excursions that the ion makes, and hence is closely related to local structure.…”

“…In contrast to the early findings of Sidebottom et al in 1997, 58 length scales in the other works were found to be several Angstroms in magnitude. 36,38,62,63 However, in MGFE systems studied by Zielniok et al, 16 as well as a re-analysis of their data by modelling the permittivity spectra Banhatti et al, 17 The proportionality constant of decay along the single-particle and many-particle routes is given by the relation. = −ln (W(∞)).…”

DIELECTRIC STUDIES IN Li2O AND CoO DOPED BOROPHOSPHATE GLASSES

“…0.50(xB2O3 . (1-x)P2O5) glasses and that were interpreted to be due to interaction between the mobile ions and the glass network [13]. The activation energy and power law exponent of conductivity showed composition dependent trends in xLi2O .…”