Dan Shechtman

Dan Shechtman is an Israeli materials scientist who discovered quasicrystals in 1982 and received the 2011 Nobel Prize in Chemistry.

Linus Pauling: Linus Pauling was an American chemist who won the Nobel Prizes in Chemistry and Peace. Pauling was the most prominent critic of Shechtman’s interpretation of the diffraction pattern.
Electron diffraction: Electron diffraction is the scattering of electrons by matter, producing patterns that reveal atomic structure. Shechtman observed the quasicrystal’s symmetry in an electron-diffraction pattern.
Aluminum–manganese alloys: Aluminum–manganese alloys are metallic materials containing aluminum and manganese. Shechtman first observed the unusual diffraction pattern in a rapidly cooled aluminum–manganese alloy.
Quasicrystal: A quasicrystal is an ordered solid whose atomic arrangement lacks the periodic repetition of ordinary crystals. This is the class of material Shechtman discovered.
Ilan Blech: Ilan Blech is an Israeli materials scientist who coauthored the first paper reporting quasicrystals. Blech collaborated with Shechtman on the paper that established the discovery.
Aperiodic order: Aperiodic order is long-range structural order without a repeating unit cell. Quasicrystals possess long-range order but lack the periodicity assumed in classical crystallography.
Rapid solidification: Rapid solidification is the fast conversion of a melt into a solid, often producing unusual microstructures. The alloy was rapidly cooled, creating conditions in which the quasicrystalline phase formed.
Penrose tiling: A Penrose tiling is a nonperiodic tiling of the plane with long-range order and fivefold symmetry. Its geometry helped explain how quasicrystals can be ordered without repeating periodically.
John Cahn: John W. Cahn was an American physical chemist and materials scientist known for work on phase transformations. Cahn recognized the significance of Shechtman’s observations and helped validate them.
Fivefold symmetry: Fivefold symmetry is invariance under rotation by one-fifth of a full turn. The forbidden fivefold diffraction symmetry was the striking feature in Shechtman’s observation.

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Crystallographic restriction theoremRelated: His observation challenged the assumption that crystalline order always entails periodicity.