Arrhenius Crossover Phenomena and Ionic Conductivity in Ionic Glass‐Forming Liquids

Abstract

Herein, the relation between the Arrhenius crossover (AC) behaviors in the structural relaxation and the electrical conductivity relaxation is explored in terms of the Bond Strength–Coordination Number Fluctuation (BSCNF) model developed by the authors. For the ionic glass‐forming liquids and solution examined, Ca2K3(NO3)7, Ca2Rb3(NO3)7, ZBLAN20 and (LiCl)0.16(H2O)0.84, the electric conductivity at high temperature resembles the behavior of the high‐temperature structural relaxation. This mutual relationship suggests a similar origin of the AC behaviors for both, structural and electrical relaxation. The difference between them is reflected in the different temperatures that demarcate the AC behaviors. The implication of this difference to the occurrence of the high ionic conduction via the decoupling mechanism is discussed in terms of the BSCNF model and the fractional Stokes–Einstein law.

Evidence for Complex Dynamics in Glassy Fast Ion Conductors: The Case of Sodium Thiosilicates

“…Our results on ionic conduction in the NS supercooled liquids are compatible with measured data in the glassy state, although a slight change in slope (i.e., activation energy) is obtained across the glass transition region (545 K) that is indicative of an Arrhenius crossover, in harmony with the salient phenomenology observed, e.g., in polymeric electrolytes , or simple oxides or modified borosilicates. , The details of the dynamics, furthermore, suggest that the Na motion is decoupled from that of the network-forming species (Si and S) as glassy relaxation onsets and that heterogeneous dynamics takes place at intermediate times and distances below 10 Å, with complex influence from the network undergoing the glass transition phenomenon. Finally, as in other modified glasses (alkali silicates − ), the present NS material also displays a channel-like motion that involves a typical length scale for Na–Na pair correlations.…”

Ionic Conductors: Effect of Temperature on Conductivity and Mechanical Properties and Their Interrelations

“…On the other hand, the result shown in Figure 7 indicates that the connectivity varies largely with temperature. This way of understanding is in line with a recent model for the viscosity of glass forming liquids [86,87]. There, the viscous flow and the structural relaxation are considered to result from thermally activated bond-breaking and bondswitching processes.…”

“…the mechanical properties and ionic conductivity in mixed network former glasses [30] and gel polymer electrolytes [31] have been reported. It will be interesting to investigate if the model mentioned above [86,87] conforms with the experimental findings reported in [30] and [31].…”

“…The structural unit forms a network and the ion that breaks the local constraint originates the ionic conduction. That is, the ionic conductivity results from the decoupling between the network and the mobile ions [86,87,90,91]. In this report we have focused in to show how the AG parameter and the Grüneisen parameter of glassy materials are related with the ionic conduction.…”

“…The structural unit forms a network and the ion that breaks the local constraint originates the ionic conduction. That is, the ionic conductivity results from the decoupling between the network and the mobile ions [86,87,90,91]. the mechanical properties and ionic conductivity in mixed network former glasses [30] and gel polymer electrolytes [31] have been reported.…”