Diffuson-related transport in ionically conducting solids

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.

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.

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.

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. 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.