Anomalies in the scaling of the dielectric α-relaxation

Schönhals, Andreas; Kremer, Friedrich; Hofmann, A.; Fischer, Erhard W.; Schlosser, E.

doi:10.1103/physrevlett.70.3459

Cited by 224 publications

(136 citation statements)

References 22 publications

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“…6 that nϭ(1Ϫ␤ KWW ) decreases with increasing temperature and becomes small ͑about 0.1 or less͒ when TϾT B . The small discrepancy of n, 54 reported by Stickel and in other publications from the same group, 55 and n obtained from our data was discussed in Refs. 29 and 30.…”

Section: B Properties Of the ␤-Relaxationcontrasting

confidence: 34%

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

246

301

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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.

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Section: B Properties Of the ␤-Relaxationcontrasting

confidence: 34%

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

246

301

View full text Add to dashboard Cite

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“…Rayleigh-Brillouin spectra at very high resolution have been presented [32] to reveal acoustic anomalies in glassy glycerol at low temperatures. The temperature behavior of the structural relaxation process has also been studied by depolarized light and neutron scattering [33,34,35], and dielectric spectroscopy [36,37,38]. Moreover, inelastic x-ray scattering [39,40,41] has been used to investigate the high-frequency dynamics of supercooled glycerol and the nature of the acoustic attenuation at low temperatures.…”

Section: Introductionmentioning

confidence: 99%

“…Several studies have been previously performed to test the MCT predictions on glycerol. Depolarized light scattering [33,34,35] and neutron [33] and dielectric [36,37,38,42] data have been subjected to MCT checks. All together these studies provide a variegated picture of the existence and the eventual location of the critical temperature, T c : the different T c evaluations span a range comprised between 250 and 310 K [33,34,35,36,37,38,42].…”

Section: Introductionmentioning

confidence: 99%

Density fluctuations in the intermediate glass-former glycerol: A Brillouin light scattering study

Comez

Fioretto

Scarponi

et al. 2003

The Journal of Chemical Physics

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Brillouin scattering has been used to measure the dynamic structure factor of glycerol as a function of temperature from the high temperature liquid to the glassy state. Our investigation aims at understanding the number and the nature of the relaxation processes active in this prototype glass forming system in the high frequency region. The associated character of glycerol is reflected by a rather simple relaxations pattern, while the contributions coming from intra-molecular channels are negligible in the GHz frequency region. The temperature behavior of the characteristic frequency and lifetime of the longitudinal acoustic modes is analyzed, suggesting that a phenomenological model which only includes the structural (α) process and the unrelaxed viscosity is able to catch the leading contributions to the dynamics of the density fluctuations. This ansatz is also supported by a combined analysis of light and inelastic x-ray scattering spectra. The temperature dependence of the characteristic time of the α-process, τα, obtained by a full-spectrum analysis conforms to the α-scale universality, i.e. the values τα revealed by different experimental techniques are proportional the ones to the others. The non-erogodicity parameter smoothly decreases on increasing the temperature, and no signature of the cusp-like behavior predicted by the idealized mode coupling theory and observed in other glass-formers is found in glycerol.

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“…Besides the gradual decrease of the (average) relaxation strength with increasing annealing temperature, a marked change in the temperature dependence of ∆ T, viz., from a decrease (for bulk EG) to an increase with increasing temperature can be recognized. While the decrease in ∆ T with increasing T is a known property of glass forming liquids, due to gradual loss in cooperativity of the R relaxation, 27 the opposite behavior is usually found for secondary relaxations and other thermally activated relaxation processes. 28 Consequently, the qualitative change in the slope d(∆ T)/dT, according to Figure 8, is in agreement with the change from VFT to Arrhenius behavior, caused by increased confinement of the dispersed EG phase.…”

Section: Figurementioning

confidence: 99%

Structure Evolution in Amylopectin/Ethylene Glycol Mixtures by H-bond Formation and Phase Separation Studied with Dielectric Relaxation Spectroscopy

et al. 2001

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The interaction between amylopectin, a starch polysaccharide, and ethylene glycol (EG) was investigated using broad-band dielectric relaxation spectroscopy. Water-free amylopectin (AP) was mixed with 21 wt % ethylene glycol. This resulted in a continuous ethylene glycol phase, as well as a molecularly mixed AP/EG fraction. After storage at room temperature or annealing, the mixture shows dynamic properties typical of a polymer with weak intermolecular interactions, suggesting that EG binds preferentially to AP and forms intrachain H-bridges leading to increased chain stiffness and thus an increased glass transition temperature. This structure evolution is accompanied by a sharp reduction in the size of the ethylene glycol droplets to a few nanometers, as revealed by pronounced confinement effects in the R-relaxation of the dispersed EG.

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Anomalies in the scaling of the dielectric α-relaxation

Cited by 224 publications

References 22 publications

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

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

Density fluctuations in the intermediate glass-former glycerol: A Brillouin light scattering study

Structure Evolution in Amylopectin/Ethylene Glycol Mixtures by H-bond Formation and Phase Separation Studied with Dielectric Relaxation Spectroscopy

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