Matter shows abrupt escape from flatness: Lead made to undergo a rapid transition from 'pancake' to hemisphere
Wednesday, September 28, 2011 - 20:30
in Physics & Chemistry
At first glance, it seems as if billions of lead atoms have mysteriously disappeared. When exposed to heat, a layer of lead coated onto a nickel surface becomes almost invisible from one moment to the next. In reality, the slightest disturbance causes these atoms to suddenly switch from a broad “flat pancake” shape to a compact hemisphere. Interestingly, this all takes place at a temperature below the melting point of lead. The hemispheres, too, consist of solid lead. So no mass has been lost, the material has simply taken on a different spatial configuration.