UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Origin of the low-temperature endotherm of acid-doped ice VI: new hydrogen-ordered phase of ice or deep glassy states?

Rosu-Finsen, A; Salzmann, CG; (2019) Origin of the low-temperature endotherm of acid-doped ice VI: new hydrogen-ordered phase of ice or deep glassy states? Chemical Science , 10 (2) pp. 515-523. 10.1039/C8SC03647K. Green open access

[thumbnail of Rosu-Finsen VoR c8sc03647k.pdf]
Preview
Text
Rosu-Finsen VoR c8sc03647k.pdf - Published Version

Download (1MB) | Preview

Abstract

On the basis of a low-temperature endotherm, it has recently been argued that cooling acid-doped ice VI at high pressures leads to a new hydrogen-ordered phase. We show that the endotherms are in fact caused by the glass transitions of deep glassy states related to ice VI. As expected for such endothermic overshoot effects, they display a characteristic dependence on pressure and cooling rate, they can be produced by sub-T_{g} annealing at ambient pressure, and they can be made to appear or disappear depending on the heating rate and the initial extent of relaxation. It is stressed that the existence of a new crystalline phase, as it has been suggested, cannot depend on the heating rate at which it is heated. X-ray diffraction shows that samples for which the low-temperature endotherm is present, weak or absent, as observed at a heating rate of 5 K min⁻¹, are structurally very similar. Furthermore, we show that the reported shifts of the (102) Bragg peak upon heating are fully consistent with our scenario and also with our earlier neutron diffraction study. Deuterated acid-doped ice VI cooled at high pressure also displays a low-temperature endotherm and its neutron diffraction pattern is consistent with deep glassy ice VI. Accessing deep glassy states of ice with the help of acid doping opens up a fascinating new chapter in ice research. Compared to pure ice VI, the glass transition temperature is lowered by more than 30 K by the acid dopant. Future work should focus on the deep glassy states related to all the other hydrogen-disordered ices including the ‘ordinary’ ice Ih.

Type: Article
Title: Origin of the low-temperature endotherm of acid-doped ice VI: new hydrogen-ordered phase of ice or deep glassy states?
Open access status: An open access version is available from UCL Discovery
DOI: 10.1039/C8SC03647K
Publisher version: http://dx.doi.org/10.1039/C8SC03647K
Additional information: © The Royal Society of Chemistry 2018. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence (https://creativecommons.org/licenses/by-nc/3.0/).
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/10061326
Downloads since deposit
83Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item