Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Formation and properties of ice XVI obtained by emptying a type sII clathrate hydrate


Gas hydrates are ice-like solids, in which guest molecules or atoms are trapped inside cages formed within a crystalline host framework (clathrate) of hydrogen-bonded water molecules1. They are naturally present in large quantities on the deep ocean floor and as permafrost, can form in and block gas pipelines, and are thought to occur widely on Earth and beyond. A natural point of reference for this large and ubiquitous family of inclusion compounds is the empty hydrate lattice1,2,3,4,5,6, which is usually regarded as experimentally inaccessible because the guest species stabilize the host framework. However, it has been suggested that sufficiently small guests may be removed to leave behind metastable empty clathrates7,8, and guest-free Si- and Ge-clathrates have indeed been obtained9,10. Here we show that this strategy can also be applied to water-based clathrates: five days of continuous vacuum pumping on small particles of neon hydrate (of structure sII) removes all guests, allowing us to determine the crystal structure, thermal expansivity and limit of metastability of the empty hydrate. It is the seventeenth experimentally established crystalline ice phase11, ice XVI according to the current ice nomenclature, has a density of 0.81 grams per cubic centimetre (making it the least dense of all known crystalline water phases) and is expected7,12 to be the stable low-temperature phase of water at negative pressures (that is, under tension). We find that the empty hydrate structure exhibits negative thermal expansion below about 55 kelvin, and that it is mechanically more stable and has at low temperatures larger lattice constants than the filled hydrate. These observations attest to the importance of kinetic effects and host–guest interactions in clathrate hydrates, with further characterization of the empty hydrate expected to improve our understanding of the structure, properties and behaviour of these unique materials.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Leaching of Ne atoms from the sII clathrate structure.
Figure 2: Lattice constants and linear expansivity of the hydrates investigated.


  1. Sloan, E. D. & Koh, C. A. Clathrate Hydrates of Natural Gases 3rd edn (CRC Press, Taylor & Francis Group, 2008)

    Google Scholar 

  2. van der Waals, J. H. & Platteeuw, J. C. Clathrate solutions. Adv. Chem. Phys. 2, 1–57 (1959)

    CAS  Google Scholar 

  3. Ballard, A. L. & Sloan, E. D. The next generation of hydrate prediction I. Hydrate standard states and incorporation of spectroscopy. Fluid Phase Equilib. 194–197, 371–383 (2002)

    Article  Google Scholar 

  4. Belosludov, V. R. et al. Thermal expansion and lattice distortion of clathrate hydrates of cubic structures I and II. J. Supramol. Chem. 2, 453–458 (2002)

    Article  CAS  Google Scholar 

  5. Koyama, Y., Tanaka, H. & Koga, K. On the thermodynamic stability and structural transition of clathrate hydrates. J. Chem. Phys. 122, 074503 (2005)

    Article  ADS  Google Scholar 

  6. Matsumoto, M. & Tanaka, H. On the structure selectivity of clathrate hydrates. J. Phys. Chem. B 115, 8257–8265 (2011)

    Article  CAS  Google Scholar 

  7. Jacobson, L. C., Hujo, W. & Molinero, V. Thermodynamic stability and growth of guest-free clathrate hydrates: a low-density crystal phase of water. J. Phys. Chem. B 113, 10298–10307 (2009)

    Article  CAS  Google Scholar 

  8. Wooldridge, P. J., Richardson, H. H. & Devlin, J. P. Mobile Bjerrum defects — A criterion for ice-like crystal-growth. J. Chem. Phys. 87, 4126–4131 (1987)

    Article  ADS  CAS  Google Scholar 

  9. Guloy, A. M. et al. A guest-free germanium clathrate. Nature 443, 320–323 (2006)

    Article  ADS  CAS  Google Scholar 

  10. Gryko, J. et al. Low-density framework form of crystalline silicon with a wide optical band gap. Phys. Rev. B 62, R7707–R7710 (2000)

    Article  ADS  CAS  Google Scholar 

  11. Bartels-Rausch, T. et al. Ice structures, patterns, and processes: a view across the icefields. Rev. Mod. Phys. 84, 885–944 (2012)

    Article  ADS  CAS  Google Scholar 

  12. Conde, M. M., Vega, C., Tribello, G. A. & Slater, B. The phase diagram of water at negative pressures: Virtual ices. J. Chem. Phys. 131, 034510 (2009)

    Article  ADS  CAS  Google Scholar 

  13. Gies, H., Liebau, F. & Gerke, H. “Dodecasile” - eine neue Reihe polytyper Einschlußverbindungen von SiO2 . Angew. Chem. 94, 214–215 (1982)

    Article  CAS  Google Scholar 

  14. Falenty, A., Salamatin, A. N. & Kuhs, W. F. Kinetics of CO2-hydrate formation from ice powders: data summary and modeling extended to low temperatures. J. Phys. Chem. C 117, 8443–8457 (2013)

    Article  CAS  Google Scholar 

  15. Alavi, S. & Ripmeester, J. A. Hydrogen-gas migration through clathrate hydrate cages. Angew. Chem. Int. Edn 46, 6102–6105 (2007)

    Article  CAS  Google Scholar 

  16. Senadheera, L. & Conradi, M. S. Rotation and diffusion of H2 in hydrogen – Ice clathrate by 1H NMR. J. Phys. Chem. B 111, 12097–12102 (2007)

    Article  CAS  Google Scholar 

  17. Dyadin, Y. A. et al. Clathrate formation in water-noble gas (hydrogen) systems at high pressures. J. Struct. Chem. 40, 790–795 (1999)

    Article  CAS  Google Scholar 

  18. Mao, W. L. et al. Hydrogen clusters in clathrate hydrate. Science 297, 2247–2249 (2002)

    Article  ADS  CAS  Google Scholar 

  19. Evans, J. S. O. Negative thermal expansion materials. J. Chem. Soc. Dalton Trans. 3317–3326 (1999)

  20. Tang, X. L. et al. Thermal properties of Si-136: Theoretical and experimental study of the type-II clathrate polymorph of Si. Phys. Rev. B 74, 014109 (2006)

    Article  ADS  Google Scholar 

  21. Röttger, K., Endriss, A., Ihringer, J., Doyle, S. & Kuhs, W. F. Lattice constants and thermal expansion of H2O and D2O ice Ih between 10 and 265 K. Acta Crystallogr. B 50, 644–648 (1994); Addendum. Acta Crystallogr. B 68, 91 (2012)

    Article  Google Scholar 

  22. Tanaka, H. Thermodynamic stability and negative thermal expansion of hexagonal and cubic ices. J. Chem. Phys. 108, 4887–4893 (1998)

    Article  ADS  CAS  Google Scholar 

  23. Pamuk, B. et al. Anomalous nuclear quantum effects in ice. Phys. Rev. Lett. 108, 193003 (2012)

    Article  ADS  CAS  Google Scholar 

  24. Lobban, C., Finney, J. L. & Kuhs, W. F. The structure of a new phase of ice. Nature 391, 268–270 (1998)

    Article  ADS  CAS  Google Scholar 

  25. Kuhs, W. F., Sippel, C., Falenty, A. & Hansen, T. C. Extent and relevance of stacking disorder in “ice Ic”. Proc. Natl Acad. Sci. USA 109, 21259–21264 (2012)

    Article  ADS  CAS  Google Scholar 

  26. Rodger, P. M. Lattice relaxation in type I gas hydrates. AIChE J. 37, 1511–1516 (1991)

    Article  CAS  Google Scholar 

  27. Kuo, J. L., Klein, M. L. & Kuhs, W. F. The effect of proton disorder on the structure of ice-Ih: A theoretical study. J. Chem. Phys. 123, 134505 (2005)

    Article  ADS  Google Scholar 

  28. Kumar, P. & Sathyamurthy, N. Theoretical studies of host-guest interaction in gas hydrates. J. Phys. Chem. A 115, 14276–14281 (2011)

    Article  CAS  Google Scholar 

  29. Anderson, B. J., Bazant, M. Z., Tester, J. W. & Trout, B. L. Application of the cell potential method to predict phase equilibria of multicomponent gas hydrate systems. J. Phys. Chem. B 109, 8153–8163 (2005)

    Article  CAS  Google Scholar 

  30. Weaire, D. & Phelan, R. A counterexample to Kelvin conjecture on minimal-surfaces. Phil. Mag. Lett. 69, 107–110 (1994)

    Article  ADS  CAS  Google Scholar 

  31. Hansen, T. C., Henry, P. F., Fischer, H. E., Torregrossa, J. & Convert, P. The D20 instrument at the ILL: a versatile high-intensity two-axis neutron diffractometer. Meas. Sci. Technol. 19, 034001 (2008)

    Article  ADS  Google Scholar 

  32. Rodríguez-Carvajal, J. Recent advances in magnetic-structure determination by neutron powder diffraction. Physica B 192, 55–69 (1993)

    Article  ADS  Google Scholar 

  33. Kuhs, W. F. Generalized atomic displacements in crystallographic structure-analysis. Acta Crystallogr. A 48, 80–98 (1992)

    Article  Google Scholar 

  34. James, F. Monte-Carlo theory and practice. Rep. Prog. Phys. 43, 1145–1189 (1980)

    Article  ADS  CAS  Google Scholar 

  35. Peters, B., Zimmermann, N. E. R., Beckham, G. T., Tester, J. W. & Trout, B. L. Path sampling calculation of methane diffusivity in natural gas hydrates from a water-vacancy assisted mechanism. J. Am. Chem. Soc. 130, 17342–17350 (2008)

    Article  CAS  Google Scholar 

  36. Buch, V. et al. Clathrate hydrates with hydrogen-bonding guests. Phys. Chem. Chem. Phys. 11, 10245–10265 (2009)

    Article  CAS  Google Scholar 

  37. Demurov, A., Radhakrishnan, R. & Trout, B. L. Computations of diffusivities in ice and CO2 clathrate hydrates via molecular dynamics and Monte Carlo simulations. J. Chem. Phys. 116, 702–709 (2002)

    Article  ADS  CAS  Google Scholar 

Download references


We thank the Bundesministeriums für Bildung und Forschung (BMBF) for financial support in the context of the first and second phase of the German SUGAR (SUbmarine Gashydrat-Lagerstätten: Erkundung, Abbau und TRansport) project. We thank the Institut Laue-Langevin (ILL) for beam time and support. We are also grateful for the assistance of H. Bartels (Göttingen), U. Kahmann (Göttingen) and A. Daramsy (ILL), as well as for discussions with P. Lafond (Göttingen).

Author information

Authors and Affiliations



W.F.K. and A.F. designed the study and prepared the Ne-hydrate samples; A.F., T.C.H. and W.F.K. performed the leaching and diffraction experiments; T.C.H. and W.F.K. analysed the data; and W.F.K. wrote the paper with contributions from A.F. and T.C.H.

Corresponding author

Correspondence to Werner F. Kuhs.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Extended data figures and tables

Extended Data Figure 1 Cage filling as a function of time for different temperatures.

A shrinking core model of the Ne leaching process fits values from sequential Rietveld refinement. Filled data points (and solid line for the fits) present the data for small cages (Ne1); open data points (and dashed lines) show data for the large cages (Ne2). Red circles and lines represent 110 K, orange squares and lines 120 K, green triangles and lines 130 K, light blue triangles and lines 135 K, dark blue flat rhombi and lines 140 K, magenta upright rhombi and lines 145 K.

Extended Data Figure 2 Diffraction patterns of Ne-filled and empty hydrate.

a, b, Rietveld fit (obtained using FullProf software32) to diffraction pattern of empty sII D2O hydrate (a) and Ne D2O hydrate (b) taken at 5 K (λ ≈ 1.1226 Å) on D20, ILL/Grenoble. The observed intensity is represented by open black circles, the calculated intensity as a blue line, the difference of both by a green line, grey shading marks the angular regions excluded in the refinement, red lines mark the positions of Bragg peaks of the hydrate, violet lines those of the aluminium sample can and orange lines those of ice Ic.

Extended Data Table 1 Polynomial coefficients of lattice constant fits*

Supplementary information

Supplementary Data

This zipped file contains 2 crystallographic information files. (ZIP 13 kb)

PowerPoint slides

Source data

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Falenty, A., Hansen, T. & Kuhs, W. Formation and properties of ice XVI obtained by emptying a type sII clathrate hydrate. Nature 516, 231–233 (2014).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing