Connection between the high-frequency crossover of the temperature dependence of the relaxation time and the change of intermolecular coupling in glass-forming liquids

2003 ◽  
Vol 68 (1) ◽  
Author(s):  
R. Casalini ◽  
K. L. Ngai ◽  
C. M. Roland
Keyword(s):  
Relaxation Time ◽  
Temperature Dependence ◽  
High Frequency ◽  
Glass Forming ◽  
Intermolecular Coupling

Temperature Dependence of Relaxation Time in Adam-Gibbs Model of Glass-Forming Liquids: Fluctuation Effects

2008 ◽  
Author(s):  
Udayan Mohanty ◽  
Albert Co ◽  
Gary L. Leal ◽  
Ralph H. Colby ◽  
A. Jeffrey Giacomin
Keyword(s):  
Relaxation Time ◽  
Temperature Dependence ◽  
Glass Forming ◽  
Gibbs Model ◽  
Fluctuation Effects

Thermodynamic and kinetic fragilities of Mg-based bulk metallic glass-forming liquids

2008 ◽  
Vol 23 (10) ◽  
pp. 2816-2820 ◽  
Author(s):  
H. Ma ◽  
H-J. Fecht
Keyword(s):  
Relaxation Time ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Temperature Dependence ◽  
Bulk Metallic Glass ◽  
Excess Entropy ◽  
Gibbs Equation ◽  
Glass Forming

The thermodynamic and kinetic fragilities of two near-eutectic Mg-based bulk metallic glass (BMG)-forming liquids, Mg61Cu28Gd11 and Mg59.5Cu22.9Ag6.6Gd11, were investigated using high-precision differential scanning calorimeter (DSC). The thermodynamic fragility denoted as F3/4 was determined by evaluating the temperature dependence of the excess entropy Sex. The heating rate dependence of the relaxation time at the glass transition temperature was investigated to measure the kinetic fragility. A positive correlation between the thermodynamic and kinetic fragilities could be established in Mg-based BMG-forming liquids on the basis of Adam-Gibbs equation in contrast to a number of other BMGs.

Hypersonic Velocity, Absorption and Relaxation in Molten CSNO3

1977 ◽  
Vol 32 (1) ◽  
pp. 57-60 ◽  
Author(s):  
H. E. Gunilla Knape ◽  
Lena M. Torell
Keyword(s):  
Relaxation Time ◽  
High Frequency ◽  
Viscosity Coefficient ◽  
Sound Waves ◽  
Frequency Range ◽  
Ultrasonic Velocities ◽  
Hypersonic Velocity ◽  
Frequency Shifts ◽  
Bulk Viscosity Coefficient ◽  
Good Agreement

Abstract Brillouin spectra of molten CSNO3 were investigated for scattering angles between 40 and 140° and in a temperature interval of 420-520 °C. An Ar+ singlemode laser was used for excitation and the total instrumental width was ~265 MHz. The measured frequency shifts and linewidths of the Brillouin components were used to determine velocities and attenuations of thermal sound waves in the frequency range 2.3-7.0 GHz. A dispersion of 4-5% was found between the present hyper­ sonic velocities and reported ultrasonic velocities. A considerable decrease in attenuation with frequency was observed in the investigated frequency range, with the value at high frequency ap­ proaching the classical attenuation. The results are in good agreement with Mountain's theory of a single relaxation time. The relaxation time of the bulk viscosity coefficient was calculated to 1.2×10-10S.

scholarly journals Difference between Brownian and Néel relaxation mechanisms in a magnetizing field

2021 ◽  
pp. 14-20
Author(s):  
Alexander V. Lebedev ◽  
Keyword(s):  
Relaxation Time ◽  
Oleic Acid ◽  
High Frequency ◽  
Cobalt Ferrite ◽  
Magnetic Moments ◽  
Relaxation Mechanism ◽  
Dynamic Susceptibility ◽  
Magnetite Particles ◽  
Magnetizing Field ◽  
Néel Relaxation

Measurements of the dynamic susceptibility of a magnetic fluid based on cobalt ferrite particles stabilized in water by a double surfactant layer have been carried out. Cobalt ferrite, in comparison with magnetite, has a significantly higher energy of magnetic anisotropy. Therefore, for particles of cobalt ferrite, the Brownian mechanism of relaxation of magnetic moments is characteristic. The Debye (with a finite relaxation time) contribution to the dynamic susceptibility and the high-frequency (dispersionless) contribution are distinguished by constructing Cole-Cole diagrams. It was found that with an increase in the magnetizing field, the Debye contribution to the dynamic susceptibility decreases, while the high-frequency one (having a zero relaxation time) remains unchanged. The indicated property of the dynamic susceptibility of a fluid with a Brownian relaxation mechanism is radically different from the properties of the susceptibility of a fluid with Néel particles. Previously, measurements were made of the susceptibility of a fluid based on magnetite particles stabilized with oleic acid in kerosene. The magnetite particles have significantly lower anisotropy energy and are characterized by the predominance of the Néel relaxation mechanism. Turning on the magnetizing field caused a decrease in both the Debye part of the susceptibility and the high-frequency part of the susceptibility of magnetite particles.

Measurement scheme to detect α relaxation time of glass-forming liquid

2019 ◽  
Vol 28 (8) ◽  
pp. 086601
Author(s):  
Xing-Yu Zhao ◽  
Li-Na Wang ◽  
Hong-Mei Yin ◽  
Heng-Wei Zhou ◽  
Yi-Neng Huang
Keyword(s):  
Relaxation Time ◽  
Glass Forming ◽  
Measurement Scheme
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