Slow dynamics in glass-forming materials at α- and β-relaxation stages based on time-convolutionless mode-coupling theory

2019 ◽  
Vol 526 ◽  
pp. 121074
Author(s):  
Michio Tokuyama
Keyword(s):  
Mode Coupling ◽  
Coupling Theory ◽  
Mode Coupling Theory ◽  
Slow Dynamics ◽  
Glass Forming ◽  
Β Relaxation ◽  
Glass Forming Materials

Dynamics in a Nonfragile Glass-Forming Liquid

1996 ◽  
Vol 455 ◽  
Author(s):  
B. Rufflé ◽  
S. Beaufils ◽  
J. Etrillard ◽  
J. Gallier ◽  
B. Toudic ◽  
...  
Keyword(s):  
Structural Relaxation ◽  
Mode Coupling ◽  
Low Frequency ◽  
Large Temperature ◽  
Coupling Theory ◽  
Mode Coupling Theory ◽  
Glass Forming ◽  
Real Change ◽  
Wide Energy ◽  
Fragile Glass

ABSTRACTThe dynamics of Na0.5Li0.5PO3 (Tg = 515 K, Tm = 749 K) a non fragile glass forming liquid has been investigated over a large temperature range (300 − 1000 K.) and in a wide energy window using various experimental techniques. The susceptibility spectra obtained by coherent neutron scattering and depolarized light scattering between 1 and 104 GHz show mainly two contributions: a low frequency vibrational peak, the so-called Boson peak and a quasielastic component, referred to the βfast process in the mode coupling theory (MCT).The data are discussed in relation to the mode coupling theory for the liquid glass transition. In particular, the temperature evolution of the susceptibility height in the βfast region is compatible with a crossover temperature Tc ∼ 620 K which is also deduced from a power law temperature dependence of the structural relaxation timescale. As a secondary βslow process, observed by 31P NMR, decouples from the structural relaxation timescale also below 600 K, a real change in the dynamics seems to occur around Tc ∼ 620 K = 1.2 Tg in this non fragile glass Conning liquid.

scholarly journals Structure and dynamics of glass-forming alloy melts investigated by application of levitation techniques

2019 ◽  
Vol 91 (6) ◽  
pp. 895-910 ◽  
Author(s):  
Dirk Holland-Moritz ◽  
Benedikt Nowak ◽  
Fan Yang ◽  
Andreas Meyer
Keyword(s):  
Mode Coupling ◽  
Short Range ◽  
Structural Information ◽  
Coupling Theory ◽  
Mode Coupling Theory ◽  
Self Diffusion ◽  
Glass Forming ◽  
Input Mode ◽  
Quasielastic Neutron ◽  
Short Range Structure

Abstract In this work results of studies on the short-range order and on the atomic dynamics in different stable and undercooled glass-forming metallic melts are reviewed. In order to undercool the melts deeply below the melting temperature and to avoid chemical reactions of the melts with crucible materials, the samples are containerlessly processed utilizing the electromagnetic or the electrostatic levitation technique. The short-range structure of the melts is studied by neutron diffraction, while the atomic dynamics are investigated by quasielastic neutron scattering. The relationship between short-range structure and atomic dynamics is discussed within the mode coupling theory of the glass transition. We will show that taking the time- and space-averaged structural information provided by measured partial structure factors as an input, mode coupling theory is able to explain the experimental results concerning the activation energies for self-diffusion and the coupling/decoupling behavior of the self-diffusion coefficients of the different alloy components.

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