Polarization effects in ionic solids and melts

TL;DR

This paper reviews how polarization effects influence the structural and dynamic properties of ionic solids and melts, highlighting recent advances in modeling these effects and their implications for understanding complex ionic systems.

Contribution

It introduces realistic polarizable interaction potentials and demonstrates their importance in explaining structural and dynamic phenomena in ionic compounds and molten salts.

Findings

Polarization stabilizes specific crystal structures.

It influences the formation of highly-coordinated multivalent ions.

Affects diffusion and interfacial properties of molten salts.

Abstract

Ionic solids and melts are compounds in which the interactions are dominated by electrostatic effects. However, the polarization of the ions also plays an important role in many respects as has been clarified in recent years thanks to the development of realistic polarizable interaction potentials. After detailing these models, we illustrate the importance of polarization effects on a series of examples concerning the structural properties, such as the stabilization of particular crystal structures or the formation of highly-coordinated multivalent ions in the melts, as well as the dynamic properties such as the diffusion of ionic species. The effects on the structure of molten salts interfaces (with vacuum and electrified metal) is also described. Although most of the results described here concern inorganic compounds (molten fluorides and chlorides, ionic oxides...), the particular case of the room-temperature ionic liquids, a special class of molten salts in which at least one species is organic, will also be briefly discussed to indicate how the ideas gained from the study of "simple" molten salts are being transferred to these more complex systems.