Diffuson-related transport in ionically conducting solids

Introduction

In DIONISOS, we aim to develop new analytical relationships for ion- and heat-transport in ionic conductors, and thus heal significant inconsistencies of the current understanding. Currently, ion- and heat transport are interpreted as unrelated phenomena; ion transport being based on local jumps, whereas heat transport being mediated by dynamic lattice vibrations called phonons.

Background

Among other studies, my pioneering works in the field of solid ionic conductors (J. Am. Chem. Soc. 2017, J. Am. Chem. Soc. 2018) opened discussions about plausibility gaps in state-of-the-art concepts, in particular regarding interactions of phonons with mobile ions. Our work has shown that by tailoring the lattice dynamics and vibrational properties of materials, the ionic transport can be affected, which cannot be explained well by current models.

Research Proposal

To this end, we propose to analyze both ion- and heat-transport in several representative materials, designed for the purpose, to test our hypothesis that it is not a classical phonon phenomenon, but rather local vibrations, quantized by the diffuson, that dominate the heat and ionic transport in fast ionic conductors.

Expected Outcomes

DIONISOS will thus provide an in-depth fundamental understanding of how local vibrational modes connect thermal to ionic transport, and ideally a new analytical relationship. A unified understanding of thermal transport and ionic transport will pave the way for further research on how local structural phenomena affect global materials properties.

Implications

In addition, a theory of linking local ionic motion with local thermal motion will be of vast value for the design of high-performance functional materials.