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 and detailed structural information on the various high pressure ice phases formed metastably at low temperatures. We find that between ∼0.4-0.7 GPa, HDA transforms at 175 K to mainly phases IV and V, and XII, and at 1-1.2 GPa to a mixture of ice VI and XII. On isothermal compression at 100 K, HDA recrystallises to an ice VII-like structure which is either partially ordered or mixed with ice VIII. Full structural data obtained by Rietveld refinements are reported for all these phases at low temperatures. Phases IV, V and XII are fully hydrogen disordered when obtained from HDA. The transformation behaviour in the 0.5-1.2 GPa range is in good agreement with the picture reported from quenched-recovered samples, although some differences persist in the recrystallisation to IV/XII mixtures. The recrystallisation behaviour of HDA over the entire pressure range appears to follow closely that of liquid water under pressure.
| Original language | English |
|---|---|
| Pages (from-to) | 117-122 |
| Number of pages | 6 |
| Journal | Zeitschrift fur Kristallographie |
| Volume | 218 |
| Issue number | 2 |
| DOIs | |
| State | Published - 2003 |
| Externally published | Yes |
Funding
results and conclusions with D. D. Klug, M. Saitta, M. C. Bellissent-Funel, and A. Hallbrucker. We thank D. J. Francis and J. Dreyer for help in the experiments. Our work (JSL, RJN, MG) is funded by a research grant from EPSRC, and supported by CCLRC through access to beamtime and other resources.