Coupling model explanation of salient dynamic properties of glass-forming substances

2001 ◽  
Vol 8 (3) ◽  
pp. 329-344 ◽  
Author(s):  
K.L. Ngai
Keyword(s):  
Dynamic Properties ◽  
Coupling Model ◽  
Glass Forming ◽  
Model Explanation

scholarly journals Water-like anomalies as a function of tetrahedrality

2018 ◽  
Vol 115 (15) ◽  
pp. E3333-E3341 ◽  
Author(s):  
John Russo ◽  
Kenji Akahane ◽  
Hajime Tanaka
Keyword(s):  
Phase Diagram ◽  
Dynamic Properties ◽  
Ambient Pressure ◽  
Dynamical Behavior ◽  
Comprehensive Understanding ◽  
Glass Forming ◽  
Silicon Carbon ◽  
Spinodal Line ◽  
Two State Model ◽  
Weber Potential

Tetrahedral interactions describe the behavior of the most abundant and technologically important materials on Earth, such as water, silicon, carbon, germanium, and countless others. Despite their differences, these materials share unique common physical behaviors, such as liquid anomalies, open crystalline structures, and extremely poor glass-forming ability at ambient pressure. To reveal the physical origin of these anomalies and their link to the shape of the phase diagram, we systematically study the properties of the Stillinger–Weber potential as a function of the strength of the tetrahedral interaction λ. We uncover a unique transition to a reentrant spinodal line at low values of λ, accompanied with a change in the dynamical behavior, from non-Arrhenius to Arrhenius. We then show that a two-state model can provide a comprehensive understanding on how the thermodynamic and dynamic anomalies of this important class of materials depend on the strength of the tetrahedral interaction. Our work establishes a deep link between the shape of the phase diagram and the thermodynamic and dynamic properties through local structural ordering in liquids and hints at why water is so special among all substances.

The effect of hydrogen bonding propensity and enantiomeric composition on the dynamics of supercooled ketoprofen – dielectric, rheological and NMR studies

2016 ◽  
Vol 18 (15) ◽  
pp. 10585-10593 ◽  
Author(s):  
K. Adrjanowicz ◽  
K. Kaminski ◽  
M. Tarnacka ◽  
K. Szutkowski ◽  
L. Popenda ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Dynamic Properties ◽  
Enantiomeric Composition ◽  
Nmr Studies ◽  
Glass Forming

We have investigated the effect of changes in the hydrogen bonding propensity and enantiomeric composition on the dynamic properties of glass-forming liquid ketoprofen.

Some examples of possible descriptions of dynamic properties of polymers by means of the coupling model

1997 ◽  
Vol 36 (3) ◽  
pp. 307-319 ◽  
Author(s):  
K. L. Ngai ◽  
Donald J. Plazek ◽  
Ronald W. Rendell
Keyword(s):  
Dynamic Properties ◽  
Coupling Model

Some examples of possible descriptions of dynamic properties of polymers by means of the coupling model

1997 ◽  
Vol 36 (3) ◽  
pp. 307-319 ◽  
Author(s):  
Kai L. Ngai ◽  
Donald J. Plazek ◽  
Ronald W. Rendell
Keyword(s):  
Dynamic Properties ◽  
Coupling Model

Structural transition and glass-forming ability of the Ni–Hf system studied by molecular dynamics simulation

2004 ◽  
Vol 19 (12) ◽  
pp. 3547-3555 ◽  
Author(s):  
J.H. Li ◽  
L.T. Kong ◽  
B.X. Liu
Keyword(s):  
Molecular Dynamics ◽  
Solid Solution ◽  
Molecular Dynamics Simulation ◽  
Solid Solutions ◽  
Dynamic Properties ◽  
Glass Forming Ability ◽  
Dynamics Simulation ◽  
Face Centered Cubic ◽  
Glass Forming ◽  
Face Centered

A tight-binding Ni–Hf potential is constructed by fitting some of the ground-state properties, such as the cohesive energy, lattice constants, and the elastic constants of some Ni–Hf alloys. The constructed potential is verified to be realistic by reproducing some static and dynamic properties of the system, such as the melting points and thermal expansion coefficients for the pure Ni and Hf as well as some of the equilibrium compounds, through molecular dynamics simulation. Applying the constructed potential, molecular dynamics simulations are performed to compare the relative stability of the face-centered-cubic (fcc)/hexagonal close-packed (hcp) solid solutions to their disordered counterparts as a function of solute concentration. It is found that the solid solutions become unstable and transform into the disordered states spontaneously, when the solute concentrations exceed the two critical solid solubilities, i.e., 25 at.% Ni for hcp Hf-rich solid solution and 18 at.% Hf for fcc Ni-based solid solution, respectively. This allows us to determine that the glass-forming ability/range of the Ni–Hf system is within 25–82 at.% Ni. Interestingly, simulations also reveal for the first time, that two mixed regions exist in which an amorphous phase coexists with a crystalline phase, and at about 18 at.% Ni, the hcp lattice turns into a new metastable phase identified to be face-centered orthorhombic structure.

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