Glasses are amorphous (non-crystalline) solids that are widely used in everyday life and in technological instruments. It is important to understand the behavior of materials that form glasses; that is, to study the dynamics of their glass transition, which is the transition from the liquid state to a glass one with decreasing temperature or increasing pressure.
Multiple theoretical models have been developed to explain the relaxation dynamics of materials that form glasses. One such model is the dynamic facilitation theory, which predicts that the dynamics of systems are heterogeneous and relaxation displays parabolic behavior.
"The general predictions of the dynamic facilitation theory hold for thermal systems," lead researcher Masaharu Isobe explains. "However, this theory had not been extended to systems controlled by pressure."
The researchers numerically investigated the glass transition behavior of two-dimensional binary mixtures of hard particles (hard disk) systems considering pressure rather than temperature as the major variable. Their aims were to determine general properties of slow relaxation under supercompressed conditions and investigate if dynamic facilitation theory was applicable to hard disk systems at high pressure.
They used the event-chain Monte Carlo method to calculate the equilibrium states of various hard disk systems at different pressures. This method allowed the equilibrium phases in the systems--including amorphous, mixed crystalline, crystalline-amorphous composite, and crystalline--to be accurately identified.
As a result, the researchers could probe the relaxation dynamics in the desired supercompressed region. They found that their results corroborated the dynamic facilitation theory in two ways.
"We confirmed that localized effective excitations randomly distributed in the equilibrated systems facilitated relaxation and average relaxation times extended with increasing compression," Isobe says. "Both of these results indicate that the dynamic facilitation theory is applicable to supercompressed hard disk systems."
These results expand fundamental knowledge of the behavior of materials under pressure, and may contribute to development of glasses with desired properties for specific applications.
The article, "Applicability of Dynamic Facilitation Theory to Binary Hard Disk Systems," authored by M. Isobe (Nagoya Institute of Technology, Japan), A. S. Keys and D. Chandler (University of California, Berkeley, USA), and J. P. Garrahan (University of Nottingham, UK), was published in Physical Review Letters (DOI: 10.1103/PhysRevLett.117.145701).
Kuniaki SHiraki | EurekAlert!
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences