Skip to main content

Thank you for visiting nature.com. 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.

  • Milestones
  • Published:

Milestone 20

What is a crystal?

Quasicrystals

Nature volume 511, pages 18–19 (2014)Cite this article

Until the 1980s, scientists felt confident that they knew the answer to this question: a crystal is a regular repeating arrangement of unit cells. Then, in 1984, Daniel Shechtman published work that challenged this definition and sent the crystallography community into turmoil.

Shechtman was investigating an alloy of aluminium that had been rapidly cooled to prevent the material from crystallizing. Electron diffraction allowed him to focus in on small regions of the material. One region of the solid produced a clean diffraction pattern, which suggested 10-fold rotational symmetry and no periodic translational symmetry, that is, the crystal seemed to be aperiodic. This was very odd. In a conventional crystal, only 1-, 2-, 3-, 4- and 6-fold symmetries are possible, with unit cells that completely fill the space available in a periodic manner. In Shechtman's own words “crystals cannot and do not exhibit icosahedral (5-fold) point group symmetry”. So these were not crystals and yet they diffracted like a crystal. What on earth was going on?

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

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

References

ORIGINAL RESEARCH PAPERS

  1. Shechtman, D. Blech, I., Gratias, D. & Cahn, J. W. Metallic phase with long-range orientational order and no translational symmetry. Phys. Rev. Lett. 53, 1951–1953 (1984)

    Article  ADS  CAS  Google Scholar 

  2. Levine, D. & Steinhardt, P. J. Quasicrystals: A new class of ordered structures. Phys. Rev. Lett. 53, 2477–2480 (1984)

    Article  ADS  CAS  Google Scholar 

FURTHER READING

  1. Penrose, R. Role of aesthetics in pure and applied research. Bull. Inst. Math. App. 10, 266 (1974)

    Google Scholar 

  2. Mackay, A. L. Crystallography and the Penrose pattern. Physica 114A, 609–613 (1982)

    Article  ADS  MathSciNet  CAS  Google Scholar 

  3. Pauling, L. Apparent icosahedral symmetry is due to directed multiple twinning of cubic crystals. Nature 317, 512–514 (1985)

    Article  ADS  CAS  Google Scholar 

  4. Maddox, J. Cold water on icosahedral symmetry. Nature 317, 471 (1985)

    Article  ADS  Google Scholar 

  5. Cahn, J. W., Gratias, D. & Shechtman, D. Pauling's model not universally accepted. Nature 319, 102 (1986)

    Article  ADS  CAS  Google Scholar 

  6. Bindi, L. et al. Natural quasicrystals. Science 324, 1306–1309 (2009)

    Article  ADS  CAS  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Senior Editor, Nature,

    Rosamund Daw

Authors
  1. Rosamund Daw
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Daw, R. What is a crystal?. Nature 511 (Suppl 7509), 18–19 (2014). https://doi.org/10.1038/nature13366

Download citation

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature13366

Search

Advanced search

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