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.

Literature:

[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

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

and

CrystalMaker®.]