Calorimetric determination of fragility in glass forming liquids: Tf vs. Tg-onset methods

Chen, Zeming; Li, Zijing; Zhang, Yaqi; Liu, Riping; Tian, Yongjun; Wang, Limin

doi:10.1140/epje/i2014-14052-y

Cited by 21 publications

(10 citation statements)

References 66 publications

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“…28), and then proceed with the analysis as in WVA. Note that T f % T g onset holds only if the same cooling and heating rates are used; otherwise (e.g., fixing a cooling rate 29 ), T g onset is not an appropriate quantity for determining fragility.…”

Section: Methodsmentioning

confidence: 99%

Phase change alloy viscosities down to Tg using Adam-Gibbs-equation fittings to excess entropy data: A fragile-to-strong transition

Wei

Lucas

Angell

2015

Journal of Applied Physics

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A method to enhance the data transfer rate of eutectic Sb-Te phase-change recording media A striking anomaly in the viscosity of Te 85 Ge 15 alloys noted by Greer and coworkers from the work of Neumann et al. is reminiscent of the equally striking comparison of liquid tellurium and water anomalies documented long ago by Kanno et al. In view of the power laws that are used to fit the data on water, we analyze the data on Te 85 Ge 15 using the Speedy-Angell power-law form, and find a good account with a singularity T s only 25 K below the eutectic temperature. However, the heat capacity data in this case are not diverging, but instead exhibit a sharp maximum like that observed in fast cooling in the Molinero-Moore model of water. Applying the Adam-Gibbs viscosity equation to these calorimetric data, we find that there must be a fragile-to-strong liquid transition at the heat capacity peak temperature, and then predict the "strong" liquid course of the viscosity down to T g at 406 K (403.6 K at 20 K min À1 in this study). Since crystallization can be avoided by moderately fast cooling in this case, we can check the validity of the extrapolation by making a direct measurement of fragility at T g , using differential scanning calorimetric techniques, and then comparing with the value from the extrapolated viscosity at T g . The agreement is encouraging, and prompts discussion of relations between water and phase change alloy anomalies. V C 2015 AIP Publishing LLC. [http://dx.

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Section: Methodsmentioning

confidence: 99%

Phase change alloy viscosities down to Tg using Adam-Gibbs-equation fittings to excess entropy data: A fragile-to-strong transition

Wei

Lucas

Angell

2015

Journal of Applied Physics

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“…Here the liquid fragility determined by DSC is denoted as the calorimetric fragility index ( m DSC ), while that determined by viscosity measurements is defined as the kinetic fragility index ( m vis ) . Moynihan et al found that the activation energy for structural relaxation determined by DSC is in good agreement with the shear viscosity activation energy. , The activation energy for structural relaxation in the glass transition region can be calculated from the cooling rate ( q c ) dependence of T f measured using DSC where E g is the activation energy for equilibrium viscous flow in the glass transition region and R is the gas constant.…”

Section: Clarifying Glass Transition Via Dscmentioning

confidence: 99%

Understanding Glass through Differential Scanning Calorimetry

et al. 2019

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Differential scanning calorimetry (DSC) is a powerful tool to address some of the most challenging issues in glass science and technology, such as the nonequilibrium nature of the glassy state and the detailed thermodynamics and kinetics of glass-forming systems during glass transition, relaxation, rejuvenation, polyamorphic transition, and crystallization. The utility of the DSC technique spans across all glass-forming chemistries, including oxide, chalcogenide, metallic, and organic systems, as well as recently discovered metal–organic framework glass-forming systems. Here we present a comprehensive review of the many applications of DSC in glass science with focus on glass transition, relaxation, polyamorphism, and crystallization phenomena. We also emphasize recent advances in DSC characterization technology, including flash DSC and temperature-modulated DSC. This review demonstrates how DSC studies have led to a multitude of relevant advances in the understanding of glass physics, chemistry, and even technology.

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“…The fragility index determined from viscosity measurements is defined as the kinetic fragility. Some of the thermodynamic property changes during the glass transition, such as the jump in isobaric heat capacity (Δ C p ) and the glass transition width (Δ T g ) are found to correlate with kinetic fragility . Moreover, due to the difficulty of measuring viscosity in some systems, we have developed a model to predict kinetic fragility ( m vis ) using calorimetric fragility ( m DSC ) across a wide range of fragilities.…”

Section: Temperature Dependence Of Liquid Viscositymentioning

confidence: 99%

“…Some of the thermodynamic property changes during the glass transition, such as the jump in isobaric heat capacity (DC p ) and the glass transition width (DT g ) are found to correlate with kinetic fragility. [43][44][45][46][47][48][49][50] Moreover, due to the difficulty of measuring viscosity in some systems, we have developed a model to predict kinetic fragility (m vis ) using calorimetric fragility (m DSC ) across a wide range of fragilities. The predicted fragility values agree well with the experimental fragility.…”

Section: Fragilitymentioning

confidence: 99%

Viscosity of glass‐forming systems

2016

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As one of the most important properties of glass-forming liquids, viscosity has drawn significant attention in both glass manufacturing and fundamental research.We review the recent scientific progress in viscosity of glass-forming systems, including both the liquid and glassy states. After the Vogel-Fulcher-Tammann (VFT) equation was introduced, many more efforts have been made to develop more accurate models to describe the temperature dependence of viscosity. In addition to the VFT equation, we also discuss three other viscosity models, viz., the Adam-Gibbs, Avramov-Milchev, and Mauro-Yue-Ellison-Gupta-Allan models. We compare the four viscosity models in terms of their theoretical underpinnings and ability to fit measured viscosity curves. The concept of fragility and the universality of the high-temperature viscosity limit are also discussed. Temperaturedependent constraint theory is introduced in detail as a powerful tool for predicting the composition dependence of viscosity. Some examples of the application of this approach to predict the glass transition temperature and fragility of various glass systems are shown. Topological constraint theory is not only of scientific interest, but also has important industrial applicability. We also discuss the thermal history dependence of viscosity in the glassy state. Some phenomenological models are briefly reviewed, while the main focus is given to the modified Mauro-Allan-Potuzak model, which can accurately predict the nonequilibrium viscosity as a function of temperature, thermal history, and composition. The correlation of viscosity with elasticity is described in terms of the shoving model. Some theoretical implications of the various viscosity models are discussed, including the concepts of the Kauzmann paradox and the ideal glass transition. Some of the evidence against the existence of these phenomena are discussed. We also review the link between glass relaxation and viscosity, that is, emphasizing that the viscosity equations presented in this review can also be used to model different types of relaxation effects based on the Maxwell relation. K E Y W O R D Sglass, modeling/model, theory, viscosity

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Calorimetric determination of fragility in glass forming liquids: Tf vs. Tg-onset methods

Cited by 21 publications

References 66 publications

Phase change alloy viscosities down to Tg using Adam-Gibbs-equation fittings to excess entropy data: A fragile-to-strong transition

Phase change alloy viscosities down to Tg using Adam-Gibbs-equation fittings to excess entropy data: A fragile-to-strong transition

Understanding Glass through Differential Scanning Calorimetry

Viscosity of glass‐forming systems

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