Water Electrolytes Solutions in Extreme Conditions: Amorphous, Crystalline and Superionic Phases – PACS

This project is an ambitious program to explore the stable and metastable phases of common (LiCl, NaCl, KCl) electrolyte water solutions which are relevant for many fields in science, ranging from cryobiology to planetary science, in regions up to now inaccessible to current techniques.
In particular, we propose to characterize water’s (poly)amorphous phases (Kohl, Loerting et al., Nature 2005) in dilute solutions at moderate pressure (few kbars), and the crystalline ice phases, highly loaded in salt (salty ices), recently discovered under high pressure (P>1GPa=10kbar) (Klotz, Bove et al. Nature Material 2009). An important and innovative part of this project will be devoted to the development of new, complementary and unique methods to characterize the microscopic structure, the proton diffusion, the dielectric and conductivity properties of these systems in extreme conditions.
The goal of our project is twofold:
-to characterize the thermodynamic and structural behavior of dilute solutions as well as their relaxation times, as a function of increasing dilution and pressure, in order to access the properties of undercooled and glassy water in the vicinity of the glass transition. We will enter this region, inaccessible to experiments (no man’s land), by the use of unique methods developed by our team, as hyperquenching (cooling rates fast enough to hinder ice nucleation) and pressure-induced amorphisation. We will then shed light on one of the fundamental issues in condensed matter physics: the link between liquid-liquid transition and polyamorphism in water (Giovambattista, Loerting et al., Nature Scientific Reports 2012).
- to search for the existence of salty-ices based on ionic species of astrophysical relevance. Furthermore, we want to characterize their new exotic properties, like the expected superionicity. This is a novel spectacular state of matter predicted to appear in water under extreme conditions (Cavazzoni et al., Science 1999) where the proton delocalizes and the crystalline system shows a ‘liquid behaviour’ concerning the proton diffusivity thus acting as a proton super-conductor. These challenging conditions will be accessible, in salty ices, to the novel experimental techniques and methodology we propose to develop. Various studies support the presence of high-pressure ice polymorphs in the interior of Galilean satellites such as Ganymede, Europa and Calisto, as well as Saturn's Titan, and there is strong evidence of subsurface salty ice crusts in some of them. If ice forms highly loaded with salts exist in nature in significant quantity, with most likely exotic properties, such as the described superionicity, their characterization would be highly relevant for the understanding of icy bodies in the Universe.