Spectral Shape of the α-Process in Supercooled Liquids Revisited

Articles you may be interested inStudy of the heating effect contribution to the nonlinear dielectric response of a supercooled liquid J. Chem. Phys. 133, 234901 (2010); 10.1063/1.3507252 Correlation between primary and secondary Johari-Goldstein relaxations in supercooled liquids: Invariance to changes in thermodynamic conditions Moderately and strongly supercooled liquids: A temperature-derivative study of the primary relaxation time scale Universal scaling, dynamic fragility, segmental relaxation, and vitrification in polymer melts

show abstract

“…15 Yet, the low-temperature data are still compatible with the aforementioned universal behavior. This is demonstrated in Fig.…”

Section: A Type a Glass Formersmentioning

confidence: 61%

Susceptibility functions for slow relaxation processes in supercooled liquids and the search for universal relaxation patterns

Blochowicz¹,

Tschirwitz²,

Benkhof³

et al. 2003

The Journal of Chemical Physics

130

114

View full text Add to dashboard Cite

show abstract

“…16, some evidence for this notion can also be found in earlier literature. 2,15,[17][18][19][20][21][22][23] In the framework of this picture, the above-mentioned two classes of glass-formers may be distinguished by just a different temperature evolution of the ␤-dynamics: In Class B materials, ␤ (T) has a much weaker temperature dependence than ␣ (T), leading to a clear separation of ␣-and ␤-peak at low temperatures. By contrast, in Class A materials, ␤ may track along ␣ more closely at all temperatures above T g and only the high-frequency flank of the ␤-peak or the excess wing is visible.…”

Section: Introductionmentioning

confidence: 99%

Nature and properties of the Johari–Goldstein β-relaxation in the equilibrium liquid state of a class of glass-formers

Ngai

Lunkenheimer

León

et al. 2001

The Journal of Chemical Physics

247

302

View full text Add to dashboard Cite

Previous dielectric relaxation measurements of glycerol and propylene carbonate and new results on propylene glycol performed below the conventional glass transition temperatures T g after long periods of aging all show that the excess wing ͑a second power law at higher frequencies͒ in the isothermal dielectric loss spectrum, develops into a shoulder. These results suggest that the excess wing, a characteristic feature of a variety of glass-formers, is the high frequency flank of a JohariGoldstein ␤-relaxation loss peak submerged under the ␣-relaxation loss peak. With this interpretation of the excess wing assured, the dielectric spectra of all three glass-formers measured at temperatures above T g are analyzed as a sum of a ␣-relaxation modeled by the Fourier transform of a Kohlrausch-Williams-Watts function and a ␤-relaxation modeled by a Cole-Cole function. Good fits to the experimental data have been achieved. In addition to the newly resolved ␤-relaxation on propylene glycol, the important results of this work are the properties of the ␤-relaxation in this class of glass-formers in the equilibrium liquid state obtained over broad frequency and temperature ranges.

show abstract

“…This extraordinary scaling behavior strongly suggests a correlation between the a process and the wing. Some criticism of the Nagel scaling arose concerning its universality [16,17] and accuracy [17,18], and minor modifications of the original scaling procedure have been proposed [17]. However, it is still commonly believed that the Nagel scaling is of significance for our understanding of glass-forming liquids, and many efforts have been made to check its validity in a variety of materials [15,16,18].…”

mentioning

confidence: 99%

Is There an Excess Wing in the Dielectric Loss of Plastic Crystals?

et al. 1999

View full text Add to dashboard Cite

The plastic crystals ortho-and meta-carborane and 1-cyanoadamantane are investigated by dielectric spectroscopy for frequencies 10 23 # n # 10 9 Hz, paying special attention to the spectral shape of the loss peaks. For the carboranes, we provide clear experimental evidence that the high-frequency wing follows a single power law over many decades in frequency. The excess wing, which shows up in a variety of glass-forming liquids as a second power law at high frequencies, is completely absent in the carboranes. In 1-cyanoadamantane, a weak excess wing shows up which can be ascribed to a Johari-Goldstein b process. We conclude that the excess wing is a property of supercooled liquids only. [S0031-9007(99)

show abstract

Spectral Shape of the α-Process in Supercooled Liquids Revisited

Cited by 47 publications

References 9 publications

Susceptibility functions for slow relaxation processes in supercooled liquids and the search for universal relaxation patterns

Susceptibility functions for slow relaxation processes in supercooled liquids and the search for universal relaxation patterns

Nature and properties of the Johari–Goldstein β-relaxation in the equilibrium liquid state of a class of glass-formers

Is There an Excess Wing in the Dielectric Loss of Plastic Crystals?

Contact Info

Product

Resources

About