222
11 Liquid Phase
One should note that any relaxation of the O:H–O bond length and energy under
perturbation will offset the phase boundaries through Einstein’s relation: DX ∝ ω X ;
and therefore, the O:H–O bond oscillation and relaxation dictate the thermodynamics
of water ice and aqueous solutions.
11.3 Supersolidity and Quasisolidity
11.3.1 Signatures
The concept of supersolidity was initially extended from the
4 He fragment at mK
temperatures, demonstrating elastic, repulsive and frictionless between the contact
motion of
4 He segments [63]. Atomic undercoordination induces local densification
of charge and energy and the associated electron polarization at the fragment surfaces
[64]. The supersolidity features the behavior of water and ice under polarization
by undercoordination or electrostatic polarization. When the molecular CN is less
than four, the H–O bond contracts spontaneously associated with O:H elongation and
strong polarization. At the surface, the H–O bond contracts from 1.00 to 0.95 Å and
the O:H expands from 1.70 to 1.95 Å associated with the O:H vibration frequency
transiting from 200 to 75 cm
−1 and the H–O from 3200 to 3450 cm
−1 [65]. The
shortened H–O bond raises its vibration frequency to a higher value that increases
again with further reduction of the molecular CN.
The quasisolidity describes phase transition from Liquid density maximum of
1.0 g cm
−3 at 4 °C to the Solid density minimum of 0.92 g cm
−3 at −15 °C. The
unusual property of the QS phase is its η L /η H < 1 defined cooling expansion and the
QS boundaries tunability. Cooling the QS phase shortens the H–O bond and lengthens
the O:H and enlarges the ∠O:H–O angle from 160° to 165° for bulks specimen [2].
The O:H–O bond relaxation under perturbation shifts its segmental phonon in
opposite directions, which offsets the phase boundaries accordingly, including the T C
for the I c –XI transition dropping from 100 K to 60 K with the droplet size [66, 67]. The
outward dispersion of the QS phase boundaries by molecular undercoordination or
electrostatic polarization depresses the T N for homogenous ice nucleation and raises
the T m for melting, which accounts for the room-temperature thin ice formation [7]
and mechanical and thermal stability of nanobubbles [68]. The supercooling of water
nanodroplets to the “no man’s land” could arise from the QS boundary dispersion
due to the high fraction of undercoordinated molecules [1]. However, compression
has a contrasting effect on the QS boundary dispersion, raising the T N and lowering
the T m , resulting in the ice Regelation—compression depresses the T m that reverse
when and the pressure is relieved [55].
Because of the strong polarization and O:H–O relaxation, the skin of water and
ice is offered with a supersolid skin that is elastoviscous, less dense (0.75 unit),
and mechanically and thermally more stable. The high elasticity of the softer O:H
phonons, ω L < 0, ensures the high adaptivity and the densely-packed surface dipoles
11 Liquid Phase
One should note that any relaxation of the O:H–O bond length and energy under
perturbation will offset the phase boundaries through Einstein’s relation: DX ∝ ω X ;
and therefore, the O:H–O bond oscillation and relaxation dictate the thermodynamics
of water ice and aqueous solutions.
11.3 Supersolidity and Quasisolidity
11.3.1 Signatures
The concept of supersolidity was initially extended from the
4 He fragment at mK
temperatures, demonstrating elastic, repulsive and frictionless between the contact
motion of
4 He segments [63]. Atomic undercoordination induces local densification
of charge and energy and the associated electron polarization at the fragment surfaces
[64]. The supersolidity features the behavior of water and ice under polarization
by undercoordination or electrostatic polarization. When the molecular CN is less
than four, the H–O bond contracts spontaneously associated with O:H elongation and
strong polarization. At the surface, the H–O bond contracts from 1.00 to 0.95 Å and
the O:H expands from 1.70 to 1.95 Å associated with the O:H vibration frequency
transiting from 200 to 75 cm
−1 and the H–O from 3200 to 3450 cm
−1 [65]. The
shortened H–O bond raises its vibration frequency to a higher value that increases
again with further reduction of the molecular CN.
The quasisolidity describes phase transition from Liquid density maximum of
1.0 g cm
−3 at 4 °C to the Solid density minimum of 0.92 g cm
−3 at −15 °C. The
unusual property of the QS phase is its η L /η H < 1 defined cooling expansion and the
QS boundaries tunability. Cooling the QS phase shortens the H–O bond and lengthens
the O:H and enlarges the ∠O:H–O angle from 160° to 165° for bulks specimen [2].
The O:H–O bond relaxation under perturbation shifts its segmental phonon in
opposite directions, which offsets the phase boundaries accordingly, including the T C
for the I c –XI transition dropping from 100 K to 60 K with the droplet size [66, 67]. The
outward dispersion of the QS phase boundaries by molecular undercoordination or
electrostatic polarization depresses the T N for homogenous ice nucleation and raises
the T m for melting, which accounts for the room-temperature thin ice formation [7]
and mechanical and thermal stability of nanobubbles [68]. The supercooling of water
nanodroplets to the “no man’s land” could arise from the QS boundary dispersion
due to the high fraction of undercoordinated molecules [1]. However, compression
has a contrasting effect on the QS boundary dispersion, raising the T N and lowering
the T m , resulting in the ice Regelation—compression depresses the T m that reverse
when and the pressure is relieved [55].
Because of the strong polarization and O:H–O relaxation, the skin of water and
ice is offered with a supersolid skin that is elastoviscous, less dense (0.75 unit),
and mechanically and thermally more stable. The high elasticity of the softer O:H
phonons, ω L < 0, ensures the high adaptivity and the densely-packed surface dipoles