Evolution of structural fluctuations in a supercooled liquid
A University of Tokyo research group has demonstrated through computer simulations that the enhancement of fluctuations in a liquid’s structure plays an important role as a liquid becomes a solid near the glass-transition point, a temperature below the melting point.
Snapshot of correlation of particle structure and dynamics at density of 0.97. Disks are colored according to the following criteria: white, low mobility and high order; black, high mobility and low order; cyan, low mobility and low order; and magenta, high mobility and high order.
Copyright : © 2015 John Russo, Hajime Tanaka.
This result increases our understanding of the origin of the glass transition and is expected to shed new light on the structure of liquids, thought until now to have been uniform and random.
Normally, a liquid changes to a solid when its temperature becomes lower than the melting point. However, some materials remain liquid even below the melting point, finally solidifying with further cooling (supercooling) at what is called the glass-transition point.
Despite intensive research over the years, its physical mechanism has remained elusive. One possibility is that increasing structural order develops in a supercooled liquid upon cooling, increasing the size of that structure and thus slowing down the dynamics and leading to the glass transition.
Because the structure of liquids that undergo a glass transition is disordered, it was difficult to detect fluctuations of such a structure, but a new method has been proposed recently.
This method does not depend on the type of liquid structure and has attracted much attention as it may enable extraction of structure size, which is key to understanding slow dynamics, for all liquids.
The research group of Professor Hajime Tanaka and Project Research Associate John Russo at the Institute of Industrial Science, the University of Tokyo, were only able to retrieve the separation distance of two particles using this method, finding instead that this method fails at extracting the correlation between more than two particles (many-body correlations) which are key for understanding the glass transition.
In a liquid composed of disk-shaped particles that do not deform no matter how much force is applied (a hard disc liquid), it is apparent that the dynamics of the liquid are dominated by a hexagonal lattice structure that is impossible to extract using this method.
“These findings not only support the physical mechanism proposed by this group that slow glassy dynamics is a consequence of the development of structural fluctuations in a supercooled liquid, but also provides a new insight into the liquid phase, which was believed to be uniform and random, and leads to a deeper understanding of the very nature of the supercooled liquid state,” says Professor Tanaka.
UTokyo Research article
Euan McKay | ResearchSEA
Scientists announce the quest for high-index materials
24.07.2017 | Moscow Institute of Physics and Technology
ADIR Project: Lasers Recover Valuable Materials
24.07.2017 | Fraunhofer-Institut für Lasertechnik ILT
3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects
A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
21.07.2017 | Event News
19.07.2017 | Event News
12.07.2017 | Event News
24.07.2017 | Power and Electrical Engineering
24.07.2017 | Materials Sciences
24.07.2017 | Materials Sciences