Theory of energy landscapes and ion transport in amorphous materials

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Ion transport in amorphous materials is of vital interest for many applications. In particular glassy electrolytes can be tailored to specific needs because of a high flexibility in their chemical compositions. They find applications in batteries, smart windows, super-capacitors, optical wave guides, sensors, and others. This research project aims at developing theoretical methods to construct energy landscapes for the ionic motion in glassy materials and to predict ionic transport properties such as conductivities and their activation energies based on this landscape construction. For the landscape construction, chemical and structural information about mutually linked units is used that are forming the host network for the ionic motion. The reliability of the theoretical developments will be checked against experimental observations. These are, in particular, diffusion profiles obtained from a novel technique of charge attachment induced ion transport, correlation functions and spectral densities measured by nuclear magnetic resonance (NMR), as well as results for local compositions and structural configurations obtained from magic angle spinning NMR and atom probe tomography. Specific objectives are the modelling of concentrations of chemical units building the glassy network, of spatial charge distributions derived from these concentrations, and calculations of ionic transport quantities by means of kinetic Monte Carlo and molecular dynamics simulations. The simulations are complemented by analytical calculations based on percolation and effective medium theories. This includes analyses on how the ion dynamics are affected by the Coulomb interaction between mobile ions and by the concentration of empty ion sites in a glass.