Heat capacity and kinetic parameters in the glass transformation interval of diopside, anorthite and albite glass

Martens, R.; Rosenhauer, M.; Büttner, Heinz; Gehlen, Kurt v.

doi:10.1016/0009-2541(87)90057-x

Cited by 30 publications

(11 citation statements)

References 20 publications

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“…The same viscosity model [49][50][51][52][53] was also used to estimate the glass transition temperatures for liquids with diopside (CaMgSi 2 O 6 ), anorthite (CaAl 2 Si 2 O 8 ) and albite (NaAlSi 3 O 8 ) compositions. The calculated glass transition temperatures corresponding to the viscosity equal to 10 12 Pa s were within 50 K of the temperature ranges where the drop of C P was reported [54]. These estimates appeared to be more accurate than the glass transition temperatures obtained experimentally from the change of slope of the heat content curves [55].…”

Section: Glasses and The Glass Transitionsupporting

confidence: 65%

Thermodynamic modelling of liquids: CALPHAD approaches and contributions from statistical physics

Becker

Ågren

Baricco

et al. 2013

Physica Status Solidi (b)

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We describe current approaches to thermodynamic modelling of liquids for the CALPHAD method, the use of available experimental methods and results in this type of modelling, and considerations in the use of atomic-scale simulation methods to inform a CALPHAD approach. We begin with an overview of the formalism currently used in CALPHAD to describe the temperature dependence of the liquid Gibbs free energy and outline opportunities for improvement by reviewing the current physical understanding of the liquid. Brief descriptions of experimental methods for extracting high-temperature data on liquids and the preparation of undercooled liquid samples are presented.Properties of a well-determined substance, B 2 O 3 , including the glass transition, are then discussed in detail to emphasize specific modelling requirements for the liquid. We then examine the two-state model proposed for CALPHAD in detail and compare results with experiment and theory, where available. We further examine the contributions of atomic-scale methods to the understanding of liquids and their potential for supplementing available data. We discuss molecular dynamics (MD) and Monte Carlo methods that employ atomic interactions from classical interatomic potentials, as well as contributions from ab initio MD. We conclude with a summary of our findings.1 Introduction Although few inorganic materials are used in their liquid state, liquids play an important role in the manufacture of many materials. This can be either because they are processed from the liquid or, for fulfilling performance criteria, the formation of the liquid phase must be avoided. Additionally, there are now a number of commercially available amorphous solids, both in the form of oxides and metallic glasses, and accurate descriptions of these sys-tems are necessary over a wide range of temperatures. How-ever, liquid phases of many inorganic substances are only sta-ble at high temperatures where the experimental determination of their properties is more challenging than at lower tem-peratures. Many amorphous phases are, at best, metastable and their properties can be difficult to measure. In addition, the data from glassy phases cannot be directly applied to modelling liquids because they have gone through the glass transition, with the attendant sharp drop in heat capacity. As a result, the experimental data for generating and evaluating models of liquids and glasses are fairly sparse. This has a significant impact on the development and refinement of models that strongly depend on the availability of thermodynamic data, such as those needed in CALPHAD modelling.CALPHAD is one of the major ways to model the thermodynamics of liquids. However, for many systems, especially the unaries (elements and sometimes compounds), the data necessary to develop, parameterize and validate models are limited. Theoretical approaches, e.g. first-principles or classical atomistic simulation, can help provide data

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Section: Glasses and The Glass Transitionsupporting

confidence: 65%

Thermodynamic modelling of liquids: CALPHAD approaches and contributions from statistical physics

Becker

Ågren

Baricco

et al. 2013

Physica Status Solidi (b)

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“…The glass tran sition temperatures obtained from Fig. 5 at 10-1000 s should and do correspond to T g data from scanning calorimetry (Martens et a/., 1987) and dilatometry (Richet, 1984). These T curves record the timescale of measurements required to ob serve the glass transition at a specific temperature.…”

Section: γ Curvessupporting

confidence: 59%

Relaxation in silicate melts

Dingwell¹,

Webb²

1990

ejm

426

253

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Abstract:The glass transition is a kinetic barrier that divides the behavior of silicate melts into two types, liquid and glassy. Liquid behavior is the equilibrium response of a melt to an applied perturbation, resulting in the determination of an equilibrium liquid property. The equilibrium may be stable (superliquidus) or metastable (subliquidus). Glassy behavior occurs when the timescale of the perturbation is too short for melt equilibration. This can occur when the frequency of an applied sinusoidal perturbation is too high or when the observation time of an experiment is too short. The time-or frequency-dependent response of the structure and properties of a melt to a perturbation is termed relaxation. Liquid and glassy behavior are relaxed and unrelaxed behavior, respectively.Linear viscoelastic theory provides mechanical models for the prediction of the isothermal transition from liquid to glassy behavior. A simple series combination of Hookean spring and Newtonian dashpot (a Maxwell element) is capable of predicting the timescale corresponding to the glass transition from the ratio of the relaxed viscosity to the infinite frequency elastic modulus. We review some experimental work on silicate melts that can be used to constrain the location of the glass transition in time-temperature space at 1 atm pressure (e.g., ultrasonic wave propagation, fiber elongation, torsional testing, scanning calorimetry).The microscopic origin of the glass transition in silicate melts is related to the exchange ofSi-O bonds. Recent" Si NMR work indicates that the Si-O bond exchange frequency matches the timescale of the glass transition. This explains the Newtonian viscosity of silicate liquids. No extended species (e.g., "polymers") can exist at higher temperatures and longer timescales than the lifetime of the fundamental Si-O bond. Silicate melts, however, become non-Newtonian as the strain rate approaches the equilibration rate of the Si-O bonds. Such a correlation between Si-O bond exchange and the viscous flow mechanism, in turn, explains the success of the Eyring relationship in relating high temperature oxygen and silicon self-diffusion to viscosity.Knowledge of the structural relaxation timescale is important in extracting equilibrium information from studies of the structure and properties of quenched glasses. Quench rate-dependent speciation data for glasses imply a temperature-dependence of the species equilibrium in the liquid state. Estimation of the relaxation times associated with the quench rates allows reconstruction of the temperature-dependence of homogeneous equilibria in liquids.Experimental work on silicate melts should consider the location of the experimental method in time-temperature space, with respect to the glass transition. Diffusivity measurements, for example, are influenced by the glass transition. When the duration of a diffusivity experiment crosses the volume relaxation time, an inflection in the temperature-dependence of diffusivity of cations is observed. A second "transition" in diff...

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“…Several successful models of the glass transition for silicate liquids (e.g., Crichton and Moynihan 1988) have used a modification of Eq. (1) with an Arrhenian form of the relaxation time (Tool 1946;Narayanaswamy 1971Narayanaswamy , 1988De Bolt et al 1976;Martens et al 1987).…”

Section: Introductionmentioning

confidence: 99%

Cooling rates of hyaloclastites: applications of relaxation geospeedometry to undersea volcanic deposits

Wilding¹,

Dingwell

Batiza

et al. 2000

Bull Volcanol

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Glass fragments from three different hyaloclastites have been used to evaluate the range of cooling rates experienced by undersea volcanic deposits. We found that the glass fragments retain structures with a range of apparent quench rates from 25 to 0.15 K min -1 . The most rapid cooling rates are interpreted to be those resulting from cooling of the lava near the water interface. Simple conductive cooling models produce a range of quench rates comparable to those of the more rapidly cooled samples. The very slow apparent quench rates are unlikely to result from simple linear cooling through the glass transition, because of the onset of crystallization; instead, they are indicators of a more complex thermal history that involves the annealing of glasses at temperatures within the glass transition interval for a dwell time sufficient to allow the relaxation of the glass to lower temperature structures. The thermal history recorded in these samples illustrates the complexity of eruptive processes and demonstrates that quench rates for natural glasses retain information relevant to more complex cooling models.

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Heat capacity and kinetic parameters in the glass transformation interval of diopside, anorthite and albite glass

Cited by 30 publications

References 20 publications

Thermodynamic modelling of liquids: CALPHAD approaches and contributions from statistical physics

Thermodynamic modelling of liquids: CALPHAD approaches and contributions from statistical physics

Relaxation in silicate melts

Cooling rates of hyaloclastites: applications of relaxation geospeedometry to undersea volcanic deposits

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