Ice IV – a remarkable self-interpenetrating structure

Ice IV (Ice four)

  • metastable in the phase space between Ice III, Ice V and Ice VI (see orange circle in the Figure above)
  • may be formed from high-density amorphous ice by slow heating from 145 K and a constant pressure of 8 kbar
  • calc. density at 110 K and 1 bar = 1.27 g/cm3

Structural features

  • proton-disordered phase
  • all water molecules are hydrogen-bonded to four others, two as donor and two as acceptor
  • exclusively 6-membered rings (two types, one almost flat, the other more puckered)
  • the most striking structural feature is that Ice IV builds a self-interpenetrating structure, but this does not consists of two independent networks but of only one net: two water molecules (shown in blue in the following Figure) bonded by H-bonds are oriented perpendicular and are running through the center of the almost flat 6-membered rings:

  • Space group: R-3c (No. 167)
  • Crystal system: trigonal
  • Lattice parameters:
    • a = b = 8.72922 Å, c = 17.06581 Å
    • α = β = 90°, γ =120°

 Here, you can download the CIF.


[1] H. Engelhardt and B. Kamb, Structure of ice IV, a metastable high-pressure phase, Journal of Chemical Physics 1981, 75, 5887-5899. DOI: 10.1063/1.442040

[2] C. G. Salzmann, I. Kohl, T. Loerting, E. Mayer and A. Hallbrucker, Raman spectroscopic study on hydrogen-bonding in recovered ice IV, Journal of Physical Chemistry B 2003, 107, 2802-2807. DOI: 10.1021/jp021534k


[Atomistic structure figures created with

K. Momma and F. Izumi, “VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data,” J. Appl. Crystallogr., 44, 1272-1276 (2011).



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