Nobel Prize: Quasi-Periodic Crystals

Crystals – familiar to all in gemstones, glittering snowflakes or grains of salt – are everywhere in nature. The study of their inner structure and properties provides us with deep insight into the arrangement of atoms in the solid state - insights that advance the scientific fields of chemistry, physics, biology and medicine.

A century has passed since crystals first yielded their secrets through the use of X-rays. Since then, crystallography, which has become the very core of structural science, has allowed us to decipher the structure of DNA, understand and manufacture computer microchips, showed us how proteins are created in cells and helped us to design powerful new materials and drugs. That is why in July 2012 the General Assembly of the United Nations designated 2014 as the International Year of Crystallography, marking 100 years since the Nobel Prize was awarded to the first crystallographers, father and son William Henry and William Lawrence Bragg.

In April 1982, while studying aluminum-manganese alloys as a visiting scholar at the National Bureau of Standards in Maryland, USA, Prof. Dan Shechtman of the Technion – Israel Institute of Technology, discovered a new form of matter, quasi-periodic crystals, also known as quasicrystals. The discovery sparked an extended scientific debate and Shechtman was forced to devote much time to convincing his colleagues of the veracity of his discovery.

Prof. Shechtman’s achievement went beyond the discovery of the quasicrystals themselves, also entailing his recognition of the significance of the discovery and determination to convince the skeptical scientific community accordingly. Nearly 30 years later Prof. Shechtman was named the sole recipient of the 2011 Nobel Prize in Chemistry. The Nobel Committee explained that although his discovery was extremely controversial, his work eventually forced scientists to reconsider their conception of the very nature of matter.

In fact, the discovery of quasi-periodic crystals opened up a new field of science. Hundreds of such materials have subsequently been discovered, with their extraordinary properties reported in thousands of research articles and more than 40 scientific books. Furthermore, the International Union of Crystallography revised its basic definition of a crystal in light of Shechtman’s breakthrough.

Written by Prof. Ehud Keinan, the Technion

Description of the stamp –
The flower-like image on the stamp is an electron microscope photo of icosahedral quasicrystal aggregates of Al4Mn, which were prepared in 1985 by Dr. Ágnes Csanády and her colleagues at the Hungarian Aluminum Industry Development Center. The background behind the “flowers” features an electron diffraction pattern from an icosahedral quasicrystal. The perfect pentagonal symmetry is highlighted in the diagram.

The stamp was issued in 2013, design: D. Ben Hador.