Deep-glassy ice VI confirmed with a combination of neutron spectroscopy and diffraction

TL;DR

This study confirms the existence of deep-glassy ice VI using combined neutron spectroscopy and diffraction, resolving previous controversies and expanding understanding of ultra-stable glasses in materials science.

Contribution

It provides the first direct experimental evidence for deep-glassy ice VI, clarifying its nature and ruling out alternative crystalline phase explanations.

Findings

Deep-glassy ice VI is confirmed by neutron measurements.

Crystallographic model of ice XV applies to H2O ice VI.

Deep-glassy ice VI is an example of ultra-stable glasses.

Abstract

The recent discovery of a low-temperature endotherm upon heating hydrochloric-acid doped ice VI has sparked a vivid controversy. The two competing explanations aiming to explain its origin range from a new distinct crystalline phase of ice to deep-glassy states of the well-known ice VI. Problems with the slow kinetics of deuterated phases have been raised, which we circumvent here entirely by simultaneously measuring the inelastic neutron spectra and neutron diffraction data of H2O samples. These measurements clearly confirm the deep-glassy ice VI scenario and rule out alternative explanations. Additionally, we show that the crystallographic model of D2O ice XV, the ordered counterpart of ice VI, also applies to the corresponding H2O phase. The discovery of deep-glassy ice VI now provides a fascinating new example of ultra-stable glasses which are encountered across a wide range of other materials.