Water site headerMasthead Island, Great Barrier ReefPrint-me keygo to Water Visitor Book contributions
Go to my page Water Structure and Science
Glacier ice

Ice phases

Water has many solid phases (ices), given with their properties below.

 

link Phase diagram
link Ice crystal data
V Known ices

V Very high pressure ices
V Computer ices (ice 0)

V Vonnegut's ice-nine

Known ices

There are sixteen or so crystalline phases (where the oxygen atoms are in fixed positions relative to each other but the hydrogen atoms may or may not be disordered but obeying the 'ice rules'j) and three amorphous (non-crystalline) phases (see [2145] for a recent review of ice research). All the crystalline phases of ice involve the water molecules being hydrogen bonded to four neighboring water molecules (see [1300] for a recent review). In most cases the two hydrogen atoms are equivalent, with the water molecules retaining their symmetry, and they all obey the 'ice rules'j. For the most part, the ordering of the protons (in fixed positions with lower entropy) occurs at lower temperatures, whereas pressure reduces the distances between second shell neighbors (lower volume and greater van der Waals effects). The H-O-H angle in the ice phases is expected to be a little less than the tetrahedral angle (109.47°), at about 107°. The Clausius Clapeyron equationn for many ice phase changes has to be adapted due to water's negative expansion coefficient and anomalous change in entropy with volume [1147c].

 

Structural data on the ice polymorphs

Ice polymorph

Density,
g cm-3 a

Protonsf Crystalh Symmetry Dielectric constant, εSi Notes
Hexagonal ice, Ih

0.92

0.926 disordered Hexagonal P63/mmc one C6 97.5  
Cubic ice, Ic

0.93q

0.933 disordered Cubic Fd bar3 m four C3    
LDA, Ia b

0.925q

  disordered Non-crystalline       As prepared, may be mixtures of several types
HDA c

1.17

  disordered Non-crystalline       As prepared, may be mixtures of several types
VHDA d

1.25

  disordered Non-crystalline        
II, Ice-two

1.17

1.195 ordered Rhombohedral R bar3 one C3 3.66  
III, Ice-three

1.14

1.160 disordered Tetragonal P41212 one C4 117 protons may be partially ordered
IV, Ice-four

1.27

1.275 disordered Rhombohedral R bar3 c one C3   metastable in ice V phase space
V, Ice-five

1.23

1.233 disordered Monoclinic C2/c one C2 144 protons may be partially ordered
VI, Ice-six

1.31

1.314 disordered Tetragonale P42/nmc one C4 193 two interpenetrating frameworks
VII, Ice-seven

1.50

1.591 disordered Cubice Pn bar3 m four C3 150 two interpenetrating ice Ic frameworks
VIII, Ice-eight

1.46

1.885 ordered Tetragonale I41/amd one C4 4 low temperature form of ice VII
IX, Ice-nine

1.16

1.160 ordered Tetragonal P41212 one C4 3.74 low temperature form of ice III, metastable in ice II space
X, Ice-ten

2.51

2.785 symmetric Cubice Pn bar3 m four C3   symmetric proton form of ice VII
XI, Ice-eleven

0.92

0.930 ordered Orthorhombic Cmc21 three C2   low temperature form of ice Ih
XI, Ice-elevenk

>2.51

  symmetric Orthorhombice PBcm distorted   Superionic
Metallic [1818] k

 

~12o

symmetric,

O-H-O bent

Monoclinice C2∕m     Superionic
XII, Ice-twelve

1.29

1.301 disordered Tetragonal I bar4 2d one C4   metastable in ice V phase space
XIII, Ice-thirteen

1.23

1.247 ordered Monoclinic P21/a one C2   ordered form of ice V phase
XIV, Ice-fourteen

1.29

1.294 mostly ordered Orthorhombic P212121 one C4   ordered form of ice XII phase
XV, Ice-fifteen

1.30

1.328 ordered Pseudo-orthorhombic P bar1 one C4   ordered form of ice VI phase

 

Ice Ih may be metastable with respect to empty clathrate structures of lower density under negative pressure conditions (that is, stretched) at very low temperatures [520]. Two different forms of ice-eleven have been described by different research groups: (a) the high-pressure form (also known as ice-thirteen) involves hydrogen atoms equally-spaced between the oxygen atoms [84] (like ice-ten) in a distorted hexagonal close packed structure whereas (b) the lower pressure, low temperature, form uses the incorporation of hydroxide defect doping (and interstitial K+ ions) to order the hydrogen bonding of ice Ih [207], that otherwise occurs too slowly. Another ice-ten has been described, being the proton ordered form of ice-six (VI); this is now known as ice fifteen. Only hexagonal ice-one (Ih), ice-three (III), ice-five (V), ice-six (VI), ice-seven (VII) and, perhaps, ice-ten (X) can be in equilibrium with liquid water (ice-ten with supercritical water), whereas all the others ices, including ice-two (II, [273]), are not stable in its presence under any conditions of temperature and pressure. The low-temperature ices, ice-two, ice-eight (VIII), ice-nine (IX), ice-eleven (low pressure form), ice-thirteen (XIII) [1002], ice-fourteen (XIV) [1002] and ice fifteen (XV) [1582] all possess (ice-nine and ice-fourteen incompletely) low entropy ordered hydrogen-bonding whereas in the other ices (except ice-ten [80] and ice-eleven where the hydrogen atoms are symmetrically placed and molecules of H2O do not have individual existence) the hydrogen-bonding is disordered even down to 0 K, where reachable; these includes all the ices that share a phase boundary with liquid water. Disordered hydrogen bonding causes positional disorder in the oxygen atoms of several pm around their crystallographic sites. Ice-four (IV) and ice-twelve (XII) [82] are both metastable within the ice-five phase space. Cubic ice (Ic) is metastable with respect to hexagonal ice (Ih). Ice-seven (VII) undergoes X-ray-induced (~9.7 keV) dissociation to an O2 - H2 alloyg at high pressure (>2.5 GPa) but reverts to ice-seven near its melting point at 700 K and 15 GPa [1383]. A new ice phase has been reported to lie on what had been thought to be the liquid (supercritical) side of ice-seven at high pressures, with approximate triple points of about 700 K, 20 GPa with liquid (supercritical) water and ice-seven and about 1500 K, 40 GPa with liquid (supercritical) and ice-ten [1521]. This may be a plastic phase where only molecular rotations are allowed [2078].


More structural data on the ice polymorphs

Ice polymorph

Molecular environments
Small ring size(s)p
Helix
Approximate O-O-O angles, °
Ring penetration hole size
Hexagonal ice, Ih
1
6
None
All 109.47±0.16
None
Cubic ice, Ic
1
6
None
109.47
None
LDA, Iab
3+
5(9), 6(55)
None
mainly 108, 109 and 111
None
HDA c
6+
5(9), 6(55)
None
broad range
None
VHDA d
6+
5(9), 6(55)
None
broad range
None [747]
II, Ice-two
2 (1:1)
6(7), 8(9),10(15)
None
80,100,107,118,124,128;
86,87,114,116,128,130
None
III, Ice-three
2 (1:2)
5(1), 7(1), 8(1)
4—fold
(1) 91,95,112,112,125,125
(2) 98,98,102,106,114,135
None
IV, Ice-four
2 (1:3)
6(7), 8(18),10(42)
None
(1) 92,92,92,124,124,124
(3) 88,90,113,119,123,128
some 6
V, Ice-five
4 (1:2:2:2)
4(2), 5(3), 6(2), 8(3),9(2),10(12),12(1)
None
(1) 82,82,102,131,131,131
(2) 88,91,109,114,118,128
(3) 85,91,101,103,130,135
(4) 84,93,95,123,125,126
8 (1 bond)
VI, Ice-six
2 (1:4)
4(5), 8(9)
None
(1) 77,77,128,128,128,128
(2) 78,89,89,128,128,128
8 (2 bond)
VII, Ice-seven
1
6
None
109.47
every 6
VIII, Ice-eight
1
6
None
109.47
every 6
IX, Ice-nine
2 (1:2)
5(1), 7(1), 8(1)
4—fold
(1) 91,95,112,112,125,125
(2) 98,98,102,106,114,135
None
X, Ice-ten
1
6
None
109.47
every 6
XI, Ice-eleven
1
6
None
109.47
None
XI, Ice-elevenk
undetermined
6/4
None
undetermined
every 6
XII, Ice-twelve
2 (1:2)
7(2), 8(3)
5—fold
(1) 107,107,107,107,115,115
(2) 67,83,93,106,117,132
None
XIII, Ice-thirteen
7 (all equal)
4(2), 5(3), 6(2), 8(3),9(2),10(12),12(1)
None
(1) 82,82,102,131,131,131
(2) 88,91,109,114,118,128
(3) 85,91,101,103,130,135
(4) 84,93,95,123,125,126
8 (1 bond)
XIV, Ice-fourteen
2 (1:2)
7(2), 8(3)
5—fold
(1) 107,107,107,107,115,115
(2) 67,83,93,106,117,132
None
XV, Ice-fifteen
2 (1:4)
4(5), 8(9)
None
(1) 77,77,122,122,134,134
(2) 87,90,94,124,129,135
8 (2 bond)

The thermal conductivities properties of crystalline and amorphous ices have been reviewed [1202]. Other stable or metastable phases of ice have been proposed (for example, Ice XIII and ice XIV were proposed earlier than their discovery [958]) but their structures were not established. Several new phases (for example ice i, 'Hexagonal Bilayer Water' and 'Pleated Sheet Water', [1985]) have only been found (so far) in modeling studies, but other ices have been found at confined surfaces. 'Metallic' water, where electrons are freed to move extensively throughout the material and the atoms of water exist as ions, probably exists as an antifluorite type structurem above 1.76 TPa [1138]. It is not thought that any other phases are stable at higher pressures than this.

 

The proposed topology of the transformations between ice XI --> ice II--> ice IX and ice VIII --> ice X has been described [1237]. [Back to Top to top of page]

Very high pressure ices

The state of ice at very high pressure above ice X cannot yet be reached experimentally and modeling gives a confusion of possibilities. As such modeling, but of lower pressure ices, does not give accurate results as compared with experimental structure information, it is expected that these results are, at best, indicative. Density functional calculations [1709] indicate a pressure-induced initial displacement of the ice-ten atomic layers to give an orthorhombic Pbcm structure. At higher pressure, this may be followed by the squeezing of the H-atoms from their midpoints to give a Pbca structure and then, at over a terapascal (TPa, 107 atm), to a metallic ice, consisting of corrugated sheets of H and O atoms with the H-atoms at the octahedral midpoints between next-nearest oxygen atoms [1709] . Alternative views have been given; one is that the orthorhombic Pbcm structure is superseded by a Pmc21 phase above 930 GPa, followed by a P21 crystal structure at about 1.3 TPa and finally the metallic C2∕m phase above about 4.8 TPa [1818]. Another study shows that trigonal P3121 and orthorhombic Pcca phases become stable in the ranges 0.77-1.44 TPa and 1.44-1.93 TPa [2114] respectively. Such ices are not molecular and may be considered as protons and oxygen dianions with mobile electrons [1666] and are expected at the core of giant planets such as Jupiter and Saturn. A new superionic phase has been proposed here with an approximate triple point of about 1000 K, 40 GPa with liquid (supercritical and ionized) water and ice-seven at high temperatures (~1500K) [1572]. A partially ionic phase consisting of alternate layers of OH- and H3O+ at low temperatures has been suggested [1810]. Several new phases may convert into one where the coordination number of oxygen increases from 4 to 5 with a significant increase of density [1818]. At pressures over about 5 TPa, it has been suggested that a phase splitting occurs with (the components of) H2O decomposing into a cubic Pa-3 H2O2 -formula phase and a hydrogen-rich phase, with metallization predicted at a higher pressure of just over 6 TPa [2114].

Computer ices

There are many other possible crystalline structures of solid water (ice) that fit with the tetrahedrality of water's hydrogen bonding and that obey the ice rules. These 'metastable' states may be generated using molecular models but whether they are important in the real world needs to be determined by experiment. One such ice is ice 0 (see below), a tetragonal structure (unit cell 12 molecules; 90º, 90º, 90º, 5.93 Å, 5.93 Å, 10.74 Å; 0.95 g cm-3) containing 5-, 6- and 7-membered rings that has been proposed as a structure formed during the crystallisation of ice 1c and ice 1h from supercooled water [2149]. Interestingly this ice 0 stucture contains partial dodecahedral clusters consisting of three linked pentamers (H2O)11 as thought to exist in supercooled water and ES.

Ice 0 [2149]; 3 x 3 x3 unitcells viewed down the x- and z-axes. The view down the y-axis is similar to that down the x-axis

In these diagrams of ice 0, the hydrogen bonding is shown ordered whereas in reality it is random, obeying the ice rules.

Interactive structures of ice 0 (Jmol) are available.

Cats Cradle. This edition published by Henry Holt and Company, 1999

Vonnegut's ice-nine

Kurt Vonnegut's highly entertaining story concerning an (imaginary) ice-nine, which was capable of crystallizing all the water in the world [83], fortunately has no scientific basis (see also IE). Ice-nine, in reality, is a proton ordered form of ice-three, and only exists at very low temperatures and high pressures and cannot exist alongside liquid water under any conditions.


Footnotes

a Left column: experimental density at atmospheric pressure but temperature of stability (this will contain crystal boundaries and faults); right column: crystallographic density [1717]. [Back]

 

b Low-density amorphous ice (LDA). The structural data in the Table is given assuming LDA has the structure of ES. [Back]

 

c High-density amorphous ice (HDA). The structural data in the Table is given assuming HDA has the structure of crushed CS. [Back]

 

d Very high-density amorphous ice (VHDA). The structural data in the Table assumes no hydrogen bond rearrangements from LDA or HDA. As VHDA is likely to be a relaxed form of HDA, this assumption seems unlikely [935]. [Back]

 

e Structure consists of two interpenetrating frameworks. [Back]

 

f Although primarily ordered or disordered, ordered arrangements of hydrogen bonding may not be perfect and disordered arrangements of hydrogen bonding are not totally random as there are correlated and non-bonded preferential effects. [Back]

 

g This ice is reported to be more likely a trigonal structure made up of 2H3Oδ++ O2δ- + H2 rather than a 2H2 + O2 alloy [1419]. [Back]

 

h Crystal cell parameters have been collated. The right-hand column gives the space group. [Back]

 

i Dielectric constants fall into two categories dependent on whether the hydrogen bonds are ordered (low values) or disordered (high values). [Back]

 

An H2O  ice molecule obeying the 'ice rules'j The 'ice rules': (also called the Bernal–Fowler rules) each water molecule has four hydrogen-bonded neighbors, two hydrogen atoms near each oxygen (~1 Å), one hydrogen atom on each O····O bond; thus H-O-H···OH2 and H2O···H-O-H are allowed but H-O-H···H-O-H and H2O···OH2 are not; see H2O molecule a right). As the H-O-H angles are about 106.6º [717], the hydrogen bonds are not straight (although shown so in the figures). Weaknesses (Bjerrum defects) in the ice crystal are apparent where the ice rules are disobeyed. Both O····O contacts, without an intervening proton (L defect, 'leer' defect) and O-H····H-O contacts (D defect, 'doppelt' defect, with two protons between the pair of oxygen atoms) may occur due to molecular rotations where neighboring water molecules fail to adjust their hydrogen bonding. Another type of defect is the ionic defect caused by the presence of H3O+ and OH- ions. [Back]

 

k Ice XI is also known as ice XIII. These structures have not been experimentally verified and, therefore perhaps, are best not referred to with the numerical designations first used. [Back]

 

m The antifluorite structure consists of an face centered cubic (FCC) unit cell with oxygen anions occupying the FCC lattice points (corners and faces) and hydrogen cations occupy the eight tetrahedral sites within the FCC lattice. [Back]

 

n The Clausius Clapeyron equation can be stated as dT/dP=TΔV/ΔH=ΔV/ΔS where P, T, H, V and S are the pressure, temperature, enthalpy, volume and entropy. This may be extended to be dT/dP=T(sign α2V2 - sign α1V1)ΔV/ΔH ,where α represents the thermal expansion coefficients, for use with phases with negative expansion coefficients including the ice phase changes LDA-->Ic, HDA-->LDA, LDA-->HDA, III-->V, V-->VI, VI-->VII and VI-->VIII [1147b]. [Back]

 

o At 5 TPa. [Back]

 

p The figures in brackets are the relative number of such rings. For the crystalline ices they are from [2021].

 

q Data corrected to 0 °C, for direct comparison to ice 1h. The densities were determined at ~ 80 K (ice 1h 0.932 g.cm-3, ice 1c 0.943 g.cm-3, LDA 0.937 g.cm-3) [2032] . [Back]

 

 

Home | Site Index | Phase diagram | Crystal data | Ice-Ih | Ice-Ic | II | III | IV | V | VI | VII | VIII | IX | X | XI | XII | XIII | XIV | XV | Amorphous ice | LSBU | Top

 

This page was last updated by Martin Chaplin on 10 July, 2014