Journal
JOURNAL OF PHYSICAL CHEMISTRY B
Volume 115, Issue 48, Pages 14141-14148Publisher
AMER CHEMICAL SOC
DOI: 10.1021/jp203985w
Keywords
-
Categories
Funding
- Austrian Science Fund (FWF) [Y391]
- European Research Council (ERC)
- Austrian Science Fund (FWF) [T 463] Funding Source: researchfish
Ask authors/readers for more resources
We investigate the downstroke transition from high- (HDA) to low-density amorphous ice (LDA) at 140 (H2O) and 143 K (D2O). The visual observation of sudden phase separation at 0.07 GPa is evidence of the first-order character of the transition. Powder X-ray diffractograms recorded on chips recovered from the propagating front show a double halo peak indicative of the simultaneous presence of LDA and HDA. By contrast, chips picked from different parts of the sample cylinder show either HDA or LDA. Growth of the low-density form takes place randomly somewhere inside of the high-density matrix. The thermal stability of HDA against transformation to LDA at ambient pressure significantly increases with decreasing recovery pressure and reaches its maximum at 0.07 GPa. A sample decompressed to 0.07 GPa is by similar to 17 K more stable than an unannealed HDA sample. An increasingly relaxed nature of the sample is also evident from the progressive disappearance of the broad calorimetric relaxation exotherm, preceding the sharp transition to LDA. Finally, we show that two independent thermodynamic paths lead to a very similar state of (relaxed) HDA at 140 K and 0.2 GPa. We argue that these observations imply an equilibrated nature of the amorphous sample in the pressure range of p less than or similar to 0.2 GPa and speculate that the observation of macroscopic phase separation involves two ultraviscous liquid phases at 140 K. This supports the scenario of a first-order liquid-liquid transition in bulk water.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available