Despite its solid appearance, glass is actually a 'jammed' state of matter that moves very slowly. Like cars in a traffic jam, atoms in a glass can't reach their destination because the route is blocked by their neighbours, so it never quite becomes a 'proper' solid.
For more than 50 years most scientists have tried to understand just what glass is. Work so far has concentrated on trying to understand the traffic jam, but now Dr Paddy Royall from the University of Bristol, with colleagues in Canberra and Tokyo, has shown that the problem really lies with the destination, not with the traffic jam.
Publishing today (22 June 2008) in Nature Materials, the team has revealed that glass 'fails' to be a solid due to the special atomic structures that form in a glass when it cools (ie, when the atoms arrive at their destination).
Royall explained: "Some materials crystallize as they cool, arranging their atoms into a highly regular pattern called a lattice. But although glass 'wants' to be a crystal, as it cools the atoms become jammed in a nearly random arrangement, preventing it from forming a regular lattice.
"Back in the 1950s, Sir Charles Frank in the Physics Department at Bristol University suggested that the arrangement of the 'jam' should form what is known as an icosahedron, but at the time he was unable to provide experimental proof. We set out to see if he was right."
The problem is you can't watch what happens to atoms as they cool because they are just too small. So using special particles called colloids that mimic atoms, but are just large enough to be visible using state-of-the-art microscopy, Royall cooled some down and watched what happened.
What he found was that the gel these particles formed also 'wants' to be a crystal, but it fails to become one due to the formation of icosahedra-like structures – exactly as Frank had predicted 50 years ago. It is the formation of these structures that underlie jammed materials and explains why a glass is a glass and not a liquid – or a solid.
Knowing the structure formed by atoms as a glass cools represents a major breakthrough in our understanding of meta-stable materials and will allow further development of new materials such as metallic glasses.
Metals normally crystallize when they cool, unfortunately stress builds up along the boundaries between crystals, which leads to metal failure. For example, the world's first jetliner, the British built De Havilland Comet, fell out of the sky due to metal failure. If a metal could be made to cool with the same internal structure as a glass and without crystal grain boundaries, it would be less likely to fail.
Metallic glasses could be suitable for a whole range of products that need to be flexible such as aircraft wings, golf clubs and engine parts.
Cherry Lewis | EurekAlert!
Glass's off-kilter harmonies
18.01.2017 | University of Texas at Austin, Texas Advanced Computing Center
Explaining how 2-D materials break at the atomic level
18.01.2017 | Institute for Basic Science
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
19.01.2017 | Earth Sciences
19.01.2017 | Life Sciences
19.01.2017 | Physics and Astronomy