High-pressure Raman spectroscopic study of the ice Ih → ice IX phase transition

Abstract

The phase boundaries of the ice phase diagram are not clear in the low‐temperature region even under low pressures. A detailed study of the Raman spectra of ice is reported at 88 K and in the pressure range 0 to 0.6 GPa. It is found that upon pressurising at 150 K ice Ih transformed into ice IX, although a transition ice Ih → ice II is expected from the existing phase diagram. No signs of recovering ice Ih can be detected after depressurising ice IX at 150 K and leaving for few hours. The ice Ih and ice IX data are analysed to determine various temperature and pressure coefficients.

Computing Investigations of Molecular and Atomic Vibrations of Ice IX

“…Garg and other groups of researchers found by Raman analysis that pressurizing ice Ih at 150 K transformed it into ice IX. 16−19…”

Compression-rate dependence of the phase transition from hexagonal ice to ice II and/or ice III

“…The pressurization from ice Ih to the stability field of ice II was studied previously by a number of researchers. [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] All studies agree that always ice II forms from ice Ih in the temperature range of 170-230 K. However, at temperatures above 230 K, both ice III and ice II were observed, 14 and at temperatures from 150-170 K ice IX ͑Refs. 23, 26, 29, and 32͒ or ice II ͑Ref.…”

Pressure-induced phase transition of ice in aqueous KOH solution

“…It should be noted that the ice formed from the aqueous KOH solution can directly transform to ice IX at 77 K, not via HDA. It is interesting to see that ice I h can transform into ice IX at a temperature below 150 K by an application of a pressure of 0.35 GPa [14]. Alternatively, it has been reported earlier [19,20] that ice IX could be obtained from ice II at around 0.3 GPa by cooling it through the stability region of ice II.…”

“…To address the question of the nature of the transformed phase produced from the KOH solution, it is noted that Garg [14] reported Raman spectral changes from ice I h to ice II and to ice IX phases in a similar p-T region. This study established the phase boundaries of the ice phase diagram in the low temperature region under low pressures.…”