On Wednesday, October 5, the Royal Swedish Academy of Sciences awarded the 2011 Nobel Prize in Chemistry to Dan Shechtman (Israel Institute of Technology) for the discovery of quasicrystals. This was a special Nobel prize as Shechtman’s discovery was long thought to be erroneous. The story of this year’s prize provides valuable insight into the process and progress of science.
The Nobel Prize website says:
"In quasicrystals, we find the fascinating mosaics of the Arabic world reproduced at the level of atoms: regular patterns that never repeat themselves. However, the configuration found in quasicrystals was considered impossible, and Dan Shechtman had to fight a fierce battle against established science. The Nobel Prize in Chemistry 2011 has fundamentally altered how chemists conceive of solid matter.
"His discovery was extremely controversial. In the course of defending his findings, he was asked to leave his research group. However, his battle eventually forced scientists to reconsider their conception of the very nature of matter…Scientists are currently experimenting with using quasicrystals in different products such as frying pans and diesel engines."
Dr. Shectman discovered an unusual patterning of solid materials; these quasicrystals show atoms forming a complex, quasiperiodic pattern rather than a regularly-repeating, crystal arrangement as in all other materials. Confirmation of quasicrystals creates a paradigm shift in the way we understand how atoms arrange themselves and has created many new opportunities for research. These unique crystals show distinct properties: they are hard, brittle, slippery and, unlike most metals, poor conductors of electricity.
The unusual chemistry uncovered by Dr. Shechtman has a connection to the world of particle and nuclear physics through Princeton’s Paul J. Steinhardt who has contributed to condensed-matter physics, cosmology, and particle physics. While at the University of Pennsylvania in the 1980s and 1990s, Steinhardt and his colleagues published several key papers providing a framework for explaining quasicrystals in a way that related to the existing knowledge of crystals. They proposed quasi-unit cells that template onto Penrose tilings in a two-dimensional plane. The new paradigm implies a closer physical relationship between quasicrystals and crystals. It appeared that both can be described in terms of the close-packing of a single cluster or unit cell. In a crystal, the unit cell packs edge-to-edge with its neighbours. Quasicrystals correspond to a generalization in which the quasi-unit cells overlap. In both cases, the formation of the particular structure appears to be explained by a low-energy atomic cluster, although the atomic arrangement in the case of quasicrystals is constrained to allow overlap. Hence, the new paradigm makes plausible why many materials form quasicrystals and, at the same time, explains why quasicrystals are less common than crystals. This theoretical work helped open the doors for future experimental confirmations (some by the same research team at Princeton and Pennsylvania) of Shechtman’s discovery.
TRIUMF congratulates Dr. Shechtman on his breakthrough in chemistry and materials science and his Nobel Prize. The work of chemists around the world, from TRIUMF to the Israel Institute of Technology, is helping to change the way we live. In special consideration of chemistry’s contribution to our daily lives, 2011 has been designated the International Year of Chemistry (IYC) by the United Nations. See TRIUMF’s collection of IYC stories online at http://www.triumf.ca/chemistry.
-- By Aaron Lao, Communications Assistant