Little evidence for dynamic divergences in ultraviscous molecular liquids

Hecksher, Tina; Nielsen, Albena I.; Olsen, Niels Boye; Dyre, Jeppe C.

doi:10.1038/nphys1033

Cited by 343 publications

(449 citation statements)

References 39 publications

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“…While important progress has been made in the understanding of the dynamics of glass-forming liquids [10][11][12][13] , a microscopic theory of glasses is still missing due to the extreme difficulty of probing the structural relaxation of a glass far below T g , either with experiments or simulations [13][14][15][16][17] .…”

mentioning

confidence: 99%

Revealing the fast atomic motion of network glasses

Baldi²,

et al. 2014

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Still very little is known on the relaxation dynamics of glasses at the microscopic level due to the lack of experiments and theories. It is commonly believed that glasses are in a dynamical arrested state, with relaxation times too large to be observed on human time scales. Here we provide the experimental evidence that glasses display fast atomic rearrangements within a few minutes, even in the deep glassy state. Following the evolution of the structural relaxation in a sodium silicate glass, we find that this fast dynamics is accompanied by the absence of any detectable aging, suggesting a decoupling of the relaxation time and the viscosity in the glass. The relaxation time is strongly affected by the network structure with a marked increase at the mesoscopic scale associated with the ion-conducting pathways. Our results modify the conception of the glassy state and asks for a new microscopic theory.

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confidence: 99%

Revealing the fast atomic motion of network glasses

Baldi²,

et al. 2014

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“…1,2 For a better understanding of physical aging and the glass transition phenomenology, it is important to assess the temperature at which the relaxation times will tend to diverge, in particular whether this will occur near T g or not until T = 0. 3 An inherent problem in obtaining relaxation time data below the calorimetric glass transition is the prohibitively long time required to attain equilibrium and to measure such a correlation decay. In a recent paper, Zhao and McKenna have addressed this issue and measured the equilibrium dynamics of poly(vinyl acetate) (PVAc) in the range from T g − 15 K to T g + 30 K, 4 using Struik's protocol 5 to determine that physical aging had been completed prior to recording the dielectric retardation, ε(t), at the target temperature.…”

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confidence: 99%

Comment on “Temperature divergence of the dynamics of a poly(vinyl acetate) glass: Dielectric vs. mechanical behaviors” [J. Chem. Phys. 136, 154901 (2012)]

Richert

2013

The Journal of Chemical Physics

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“…(8), (7) when ν 0 tends to zero (that is the relaxation time diverges), which usually labeled as "ideal-glass" state. Although the exact physical sense of "ideal-glass" parameters (as well as a theoretical ground of the VFT equation) is still a subject of debates 62,63 , but it seems to us worth plotting both types of the parameters (T g , P g on the one hand and T 0 , P 0 on the other) in the same figure (Fig. 10) where we also add some available literature data.…”

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confidence: 99%

Dielectric spectroscopy and ultrasonic study of propylene carbonate under ultra-high pressures

Kondrin

Gromnitskaya²,

Pronin³

et al. 2012

The Journal of Chemical Physics

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We present the high pressure dielectric spectroscopy (up to 4.2 GPa) and ultrasonic study (up to 1.7 GPa) of liquid and glassy propylene carbonate (PC). Both of the methods provide complementary pictures of the glass transition in PC under pressure. No other relaxation processes except α-relaxation have been found in the studied pressure interval. The propylene carbonate liquid is a glassformer where simple relaxation and the absence of β-relaxation are registered in the record-breaking ranges of pressures and densities. The equation of state of liquid PC was extended up to 1 GPa from ultrasonic measurements of bulk modulus and is in good accordance with the previous equations developed from volumetric data. We measured the bulk and shear moduli and Poisson's ratio of glassy PC up to 1.7 GPa. Many relaxation and elastic properties of PC can be qualitatively described by the soft-sphere or Lennard-Jones model. However, for the quantitative description of entire set of the experimental data, these models are insufficient. Moreover, the Poisson coefficient value for glassy PC indicates a significant contribution of non-central forces to the intermolecular potential. The well-known correlation between Poisson's ratio and fragility index (obtained from dielectric relaxation) is confirmed for PC at ambient pressure, but it is violated with pressure increase. This indicates that different features of the potential energy landscape are responsible for the evolution of dielectric response and elasticity with pressure increase.

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Little evidence for dynamic divergences in ultraviscous molecular liquids

Cited by 343 publications

References 39 publications

Revealing the fast atomic motion of network glasses

Revealing the fast atomic motion of network glasses

Comment on “Temperature divergence of the dynamics of a poly(vinyl acetate) glass: Dielectric vs. mechanical behaviors” [J. Chem. Phys. 136, 154901 (2012)]

Dielectric spectroscopy and ultrasonic study of propylene carbonate under ultra-high pressures

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