Dan Shechtman, the Philip Tobias professor of materials engineering at the Haifa Technion Israel Institute of Technology, was awarded the 2011 Nobel Prize in Chemistry last week for his discovery of quasicrystals—a form of matter with an atomic structure that was previously thought impossible.
In 1982, Shechtman discovered a new atomic structure when studying a rapidly cooled mix of aluminum and manganese. Unlike a regular crystal, which has an orderly, repeating structure, this material contained a pattern that never repeated. Many other kinds of quasicrystals have been discovered since then.
In 1992, the International Union of Crystallography changed the official definition of the crystal to incorporate Shechtman’s discovery.
TR: Are there opportunities to invent new types of materials because of quasicrystals?
Shechtman: There is always something new in quasicrystals. There are so many people working on it around the world, so every month there are new developments. If you use a material for an application, then you need a special property that will be better than other materials—otherwise, why use this material? Quasi-periodic materials have certain properties which are unique, such as electrical properties, optical properties, hardness and nonstick properties. The direction of light through this material is different. Electrically, they behave in a very peculiar way depending on temperature. Some of these properties have been put to use.
What was the first product based on quasicrystals?
The first application was nonstick coating on frying pans and cooking utensils. If you cook on quasicrystals, your omelet will not stick to it, like Teflon. But unlike Teflon, if you use a knife in the [quasicrystal] skillet, you will ruin the knife. When you have Teflon and you use a knife, you ruin the Teflon. Ruined Teflon is not healthy. I have a frying pan which is plasma-coated with quasicrystals and it works fine. It was made by a French company, Sitram. They closed the production line because they had a few problems in the reaction of the coating with salt. If people cook with a lot of salt it will etch the quasicrystalline coating. People didn’t like it, so they did not continue.
The Nobel citation says that quasicrystals are brittle but they can reinforce steel “like armor.” What are the practical applications?
Sandvik, a company in Sweden, produces a precipitation-hardened stainless steel that has interesting properties. The steel is strengthened by small quasicrystalline particles and it does not corrode. It is an extremely strong steel. It is used for anything that touches the skin, for instance, razor blades or surgery tools. When a material deforms in such a way that it will not spring back, in most cases, the deformation is due to a process called dislocation glide. There are defects in the material that cause dislocations. If they are free to move, then it is easy to bend the material. But if something stops them, then it is more difficult and the material is harder and stronger. These little quasicrystalline particles impede the motion of dislocation in the material.