AsianScientist (Feb. 5, 2015) – Does glass ever stop flowing? Combining computer simulation and information theory—originally invented for telephone communication and cryptography—researchers have set out to answer this puzzling question. Their results have been published in Nature Communications.
While watching a glass blower at work, we can clearly see the liquid nature of hot glass. Once the glass has cooled down to room temperature though, it becomes a solid and we can pour wine in it or make window panes out of it.
On a microscopic scale, solidification means that molecules have settled into a crystalline structure. And yet, when looked at under the microscope, it appears glass never settles down but keeps flowing, albeit extremely slowly—so slowly, in fact, that it would take over ten million years for a window pane to flow perceptibly.
This puzzle of a material which seems solid to any observer while appearing fluid under the microscope is an old one. Even with the help of today’s supercomputers it seems impossible to verify in simulations whether a glass ever stops flowing.
To answer the question of what happens at very low temperature, and whether the whole material becomes truly solid, researchers in Bristol’s Schools of Physics, Chemistry and Mathematics led by Dr. Paddy Royall and Dr. Karoline Wiesner, teamed up with Professor Ryoichi Yamamoto of Kyoto University.
They discovered that the size of the solid-like regions of the material increases over time and that atoms in the solid-like regions organize into geometrical shapes such as icosahedra.
“We found that the size of the solid regions of icosahedra would grow until eventually there would be no more liquid regions and so the glass should be a true solid,” Royall explained.
Understanding the parameters of glass formation could help in the develop of new materials such as metallic glasses and chalcogenide glasses which have application in next generation memory storage devices.
The article can be found at: Dunleavy et al. (2015) Mutual Information Reveals Multiple Structural Relaxation Mechanisms in a Model Glass Former.
—–
Source: University of Bristol.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.
