24.6 Phase Transition by Compression and Ionic Polarization
489
The high-pressure Raman spectra from the concentrated NaI/H 2 O solutions
revealed the following, see Fig. 24.11b [23]:
(1) The P C1 for the Liquid-VI transition increases faster than the P C2 with NaI
concentration till its maximum at 3.0 GPa and 0.10 concentration. The P C1
approaches to the P C2 and eventually meets at the 3.3 GPa and 350 K triple
phase junction.
(2) The P C2 for VI-VII transition changes insignificantly with concentration, keeping almost at the VI–VII boundary in the phase diagram, which contrasts with
the trend of the solution type effect.
(3) The concentration trend of the P C1 along the L-VI boundary is equivalent to the
simultaneous compressing and heating in the phase diagram.
The discrepancy between the solute type and the concentration on the P Cx arises from
the involvement of anion-anion repulsion that weakens the local electric field of the
hydration volume at higher concentrations. Solute type determines the nature and the
extent of the initial electrification; concentration increase modulates the local electric
field and the extent of the initial H–O bond energy storage. The P C2 is less sensitive
than the P C1 to the change of solute concentration because of the highly-compressed
O:H–O bond is less sensitive to the local electric field of the hydration volume and
the compression. The deformed O:H–O bond is harder to deform further than those
less-deformed under the same pressure.
One may note that, the O:H–O bond is very sensitive to the environment such as
pressure holding time, temperature, and phase precipitation. The measurement may
not be readily reproducible but the trends of measurements and the physical origin
always hold. The maximal P C2 , 3.27 > 3.05 > 2.23 GPa, for the 0.016 NaI/H 2 O
solution [22], the 0.10 NaI/H 2 O, and the deionized water, demonstrates clearly the
Hofmeister effect, the presence of the anion-anion repulsion, on the critical pressures
for the room-temperature phase transition, as compared in Fig. 24.11.
24.7 Summary
An extension of the conventional phonon spectroscopy to the DPS has enabled resolution of the fraction and stiffness of O:H–O bonds transiting from the mode of
ordinary water to their hydration and conditioned water, which amplifies solvation
study from the molecular dynamics in temporal and spatial domains to hydration
bonding energetic dynamics. Table 24.2 summarizes observations of the O:H–O
segmental cooperative relaxation in length, vibration frequency, and water surface
stress upon external excitation with respect to standard situation at 277 K.
The combination of the O:H–O bond cooperativity premise and the DPS strategy
has enabled development of new knowledge, resolution to anomalies, and strategies
for deep engineering of water ice in resolving the multifield effect on the HB network
and properties of water and solutions. The DPS has allowed quantitative information
489
The high-pressure Raman spectra from the concentrated NaI/H 2 O solutions
revealed the following, see Fig. 24.11b [23]:
(1) The P C1 for the Liquid-VI transition increases faster than the P C2 with NaI
concentration till its maximum at 3.0 GPa and 0.10 concentration. The P C1
approaches to the P C2 and eventually meets at the 3.3 GPa and 350 K triple
phase junction.
(2) The P C2 for VI-VII transition changes insignificantly with concentration, keeping almost at the VI–VII boundary in the phase diagram, which contrasts with
the trend of the solution type effect.
(3) The concentration trend of the P C1 along the L-VI boundary is equivalent to the
simultaneous compressing and heating in the phase diagram.
The discrepancy between the solute type and the concentration on the P Cx arises from
the involvement of anion-anion repulsion that weakens the local electric field of the
hydration volume at higher concentrations. Solute type determines the nature and the
extent of the initial electrification; concentration increase modulates the local electric
field and the extent of the initial H–O bond energy storage. The P C2 is less sensitive
than the P C1 to the change of solute concentration because of the highly-compressed
O:H–O bond is less sensitive to the local electric field of the hydration volume and
the compression. The deformed O:H–O bond is harder to deform further than those
less-deformed under the same pressure.
One may note that, the O:H–O bond is very sensitive to the environment such as
pressure holding time, temperature, and phase precipitation. The measurement may
not be readily reproducible but the trends of measurements and the physical origin
always hold. The maximal P C2 , 3.27 > 3.05 > 2.23 GPa, for the 0.016 NaI/H 2 O
solution [22], the 0.10 NaI/H 2 O, and the deionized water, demonstrates clearly the
Hofmeister effect, the presence of the anion-anion repulsion, on the critical pressures
for the room-temperature phase transition, as compared in Fig. 24.11.
24.7 Summary
An extension of the conventional phonon spectroscopy to the DPS has enabled resolution of the fraction and stiffness of O:H–O bonds transiting from the mode of
ordinary water to their hydration and conditioned water, which amplifies solvation
study from the molecular dynamics in temporal and spatial domains to hydration
bonding energetic dynamics. Table 24.2 summarizes observations of the O:H–O
segmental cooperative relaxation in length, vibration frequency, and water surface
stress upon external excitation with respect to standard situation at 277 K.
The combination of the O:H–O bond cooperativity premise and the DPS strategy
has enabled development of new knowledge, resolution to anomalies, and strategies
for deep engineering of water ice in resolving the multifield effect on the HB network
and properties of water and solutions. The DPS has allowed quantitative information