Metastable ice VII at low temperature and ambient pressure

  title={Metastable ice VII at low temperature and ambient pressure},
  author={Stefan Klotz and J. M. Besson and Gerard J. Hamel and Richard J. Nelmes and John S. Loveday and W G Marshall},
Ice exhibits many solid-state transformations under pressure, and also displays a variety of metastable phases. Most of the high-pressure phases of ice can be recovered at ambient pressure provided that they are first cooled below about 100 K. These ice polymorphs might exist on the surfaces of several satellites of the outer planets. One of the few exceptions to this (meta)stability on quenching has been ice VII, the dominant high-pressure phase. Here we show that isothermal compression of D2O… 
Kinetic boundaries and phase transformations of ice i at high pressure.
These extensive investigations provide previously missing information on the phase diagram of water, especially on the kinetic paths that result in formation of phases which otherwise are not accessible; these results are keys for understanding the phase relations including the formation of metastable phases.
Convergent Raman features in high density amorphous ice, ice VII, and ice VIII under pressure.
The high-pressure behavior of H(2)O ice at temperatures below 100 K has been investigated by Raman spectroscopy and the results suggest structural changes having a common origin.
High density amorphous ice at room temperature
High density amorphous (HDA) ice is formed from metastable ice VII in the stability field of ice VI under rapid compression using dynamic-diamond anvil cell (d-DAC) and results from structural similarities between HDA and ice VII, indicating that structural instabilities of parent ice VII and Ih drive the pressure-induced amorphization.
Infrared observation of the phase transitions of ice at low temperatures and pressures up to 50 GPa and the metastability of low-temperature ice VII
The phase transitions of H 2 O ice were investigated by infrared-absorption measurements in the P, T ranges of 0.2-50 GPa and 20-298 K. Under compression at temperatures below 150 K, ices II and VI
Computer Simulations on Phase Transitions in Ice
Ice has a very rich phase diagram (Petrenko and Whitworth 1999) as shown in Figure 1⇓. Up to now, sixteen crystalline phases have been identified experimentally. All crystalline phases except ice X
Ice XII forms on compression of hexagonal ice at 77 K via high-density amorphous water
Samples of high-density amorphous water (HDA) were prepared by compression of hexagonal ice (ice Ih) in a piston-cylinder apparatus at 77 K up to 1.8 GPa, recovered at ambient pressure under liquid
Recrystallisation of HDA ice under pressure by in-situ neutron diffraction to 3.9 GPa
Abstract We have studied by in-situ neutron diffraction the recrystallisation behaviour of HDA ice in the pressure range 0.3–3.9 GPa, i.e. the entire stability range of HDA. We report quantitative
Temperature-dependent kinetic pathways featuring distinctive thermal-activation mechanisms in structural evolution of ice VII
A perspective on the metastability and complexity of the energy landscape in temperature/time-dependent structural evolution in amorphous ices is presented and large-scale molecular-dynamics calculations show that the structural evolution from HDA to LDA is continuous and involves substantial movements of the water molecules at the nanoscale.
Effect of heating rate and pressure on the crystallization kinetics of high-density amorphous ice on isobaric heating between 0.2 and 1.9 GPa
The crystallization kinetics of high-density amorphous ice (HDA), made by pressure-amorphizing hexagonal ice at 77 K, and its dependence on heating rate and pressure was studied on isobaric heating


New transformations between crystalline and amorphous ice
AMONG the unusual physical properties of H2O, its behaviour at low temperatures and high pressures is particularly anomalous and incompletely understood1–3. Mishima et al.1,2 have shown that
An apparently first-order transition between two amorphous phases of ice induced by pressure
We recently reported1 a transition from ice Ih to a high-density amorphous phase at 10 kbar, 77 K. Here we report that low-density amorphous ice (density 0.94 g cm−3) compressed at 77 K transforms to
Structure and hydrogen ordering in ices VI, VII, and VIII by neutron powder diffraction
The structures of deuterated ices VI, VII, and VIII have been studied under their conditions of stability by neutron powder diffraction. The mode of ordering of (tetragonal) ice VIII is clearly
Neutron-diffractions study of phase transitions of high-pressure metastable ice VIII
The transformation of a quenched phase of high-pressure ice as a result of heating it from 94 K to 290 K has been studied by means of neutron-diffraction in real time. The following sequence of
Neutron diffraction study of the structure of deuterated ice VIII to 10 GPa.
The pressure dependence of the structure of deuterated ice VIII has been studied by time-of-flight neutron powder diffraction up to 10 GPa and it appears that the form of the O-H potential is constant with pressure.
Structure of high‐density amorphous water. I. X‐ray diffraction study
X‐ray diffraction measurements up to momentum transfer q=16 A−1 were performed at atmospheric pressure on both the high‐density form of amorphous ice obtained by pressurization of crystalline ice Ih
Structure of high‐density amorphous water. II. Neutron scattering study
High‐density amorphous water is studied by neutron scattering in a Q range extending to 16 A−1. The low density form of amorphous water is also analyzed and compared with previous results. There are