Non-equilibrium entropy of glasses formed by continuous cooling

Mauro, John C.; Gupta, Prabhat K.; Loucks, Roger J.; Varshneya, Arun K.

doi:10.1016/j.jnoncrysol.2008.09.044

Cited by 13 publications

(20 citation statements)

References 53 publications

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“…Recently Mauro, Gupta, Varshneya and coworkers denied the existence of a residual entropy at zero Kelvin for glasses [21,22]. They claimed that cooling a glass from T g to zero Kelvin results in exactly one special configuration (section 6 of [21] and last paragraphs of section 3 on page 603 of [22]).…”

Section: Interpreting Glass Formation and The Residual Entropy Of Glassmentioning

confidence: 99%

“…They claimed that cooling a glass from T g to zero Kelvin results in exactly one special configuration (section 6 of [21] and last paragraphs of section 3 on page 603 of [22]). The entropy for a special configuration is in fact zero, if one is able to specify the configuration exactly.…”

Section: Interpreting Glass Formation and The Residual Entropy Of Glassmentioning

confidence: 99%

“…And in section 6, first paragraph of [22]: "By accounting for a continuous breakdown of ergodicity at the glass transition, we can compute the gradual loss of entropy experienced by realistic glass-forming systems under continuous cooling".…”

Section: Interpreting Glass Formation and The Residual Entropy Of Glassmentioning

confidence: 99%

“…0 (irrespective of the system being ergodic or non-ergodic)" or in plain words "entropy is never lost" (you always will find it and even some more of it in most cases). Since the authors of [21,22] fail to explain or demonstrate where the entropy of their claimed loss is transferred to, their claims are not substantiated but in conflict with the second law of thermodynamics and do not need further consideration.…”

Section: Interpreting Glass Formation and The Residual Entropy Of Glassmentioning

confidence: 99%

“…The situation is different for a perfect stable crystal: if the position of one atom is known, one needs only a small set of num-bers, which in addition can be determined by measurements, to characterize the average positions of all other atoms or core ions of the crystal and even the wave functions of the electrons and holes (not considered either by the authors of [21,22]). These data are unique and correspond to negligible entropy at low temperatures (neglecting the mixing of the isotopes).…”

Section: Interpreting Glass Formation and The Residual Entropy Of Glassmentioning

confidence: 99%

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Melting and glass transition as mixing processes

Hoffmann¹

2011

Materialwissenschaft Werkst

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Melting of chemically bonded solids has been explained recently by transitions of electrons in higher electron states. Such transitions are shown to cause decomposition of the crystals into many units or sub-systems build-up of one or few atoms that mix in the melt. Most chemical elements possess molar melting entropies, DS m , in the order of the universal molar gas constant, R, or less, which is expected for mixing of a small number of differing groups of particles totalling one mole. Only in the case of crystals with bonding via sp 3 -and similar hybrids the molar melting entropy is much larger. This observation can be interpreted by a massive change of the phonon spectra of the melting solids in addition to the decomposition into mixing units. Upon cooling the melt below the glass transition temperature, T g , the mixed decomposition products of the melt are frozen in. This frozen-in mixing entropy cannot be removed from the undercooled melt and -finally -the glass by thermal conduction and remains stored in the glass until the absolute zero of the temperature. Removal of the mixing entropy is possible only by reordering of the constituents or crystallisation. Since the entropy is frozen-in near and above T g not only entropy but also enthalpy is frozen-in, which is often neglected in the literature. The specific amounts of the entropy and enthalpy frozen-in are not unique for a given glass but depend on the status of relaxation.Keywords: Glass transformation / glass transition / entropy of glass / mixing entropy / Kauzmann's paradox / Schmelzen chemisch gebundener Festkörper wurde vor kurzem durch Übergänge von Elektronen in höhere Energiezustände erklärt. Es wird nun gezeigt, dass Kristalle infolge solcher Übergänge in viele Teile oder Untereinheiten zerlegt werden, die aus einem oder wenigen Atomen bestehen. Die meisten chemischen Elemente haben daher molare Schmelzentropien DS m im Bereich der universellen Gaskonstante R oder darunter, was für Mischungen aus wenigen Teilchensorten von insgesamt einem Mol erwartet wird. Nur im Fall von Kristallen mit sp 3 -und ähnlichen Hybridbindungen zwischen den Atomen ist die Schmelzentropie viel grösser. Diese Beobachtung kann durch eine starke ¾nderung des Phononspektrums der geschmolzenen Festkörper zusätzlich zur Zerlegung in mischende Untereinheiten gedeutet werden. Kühlt man die Schmelze unter die Glastransformationstemperatur T g ab, werden die Zerlegungsprodukte in der Schmelze eingefroren. Die eingefrorene Mischungsentropie kann aus der unterkühlten Schmelze bzw. dem schließ-lich gebildeten Glas durch Wärmeleitung nicht abgeführt werden und bleibt daher im Glas bis zum absoluten Nullpunkt der Temperatur gespeichert. Ableitung ist nur möglich, wenn die Bestandteile zuvor umgeordnet werden bzw. kristallisieren. Da die Entropie oberhalb und in der Nä-he von T g eingefroren wird, wird mit der Entropie gleichzeitig Enthalpie eingefroren, was in der Literatur oftmals vernachlässigt wird. Die spezifischen Mengen an eingefrorener Entropie und Enthalpie sind für ein Gl...

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Section: Interpreting Glass Formation and The Residual Entropy Of Glassmentioning

confidence: 99%

Section: Interpreting Glass Formation and The Residual Entropy Of Glassmentioning

confidence: 99%

Section: Interpreting Glass Formation and The Residual Entropy Of Glassmentioning

confidence: 99%

Section: Interpreting Glass Formation and The Residual Entropy Of Glassmentioning

confidence: 99%

Section: Interpreting Glass Formation and The Residual Entropy Of Glassmentioning

confidence: 99%

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Melting and glass transition as mixing processes

Hoffmann¹

2011

Materialwissenschaft Werkst

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Energy and entropy of crystals, melts and glasses or what is wrong in Kauzmann's paradox?

Hoffmann¹

2012

Materialwissenschaft Werkst

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In order to understand the thermodynamic properties of solids and melts one has to consider simultaneously their entropy and energy as a function of temperature. Therefore, the molar entropy, S, and enthalpy (energy), H, of crystals, glasses and melts of the same one‐component systems have been suitably depicted including the transformation from the melt into a solid, i. e. a glass or crystal. S and H of glasses correspond to a simple continuation of these functions from the molten state to lower temperatures. Since crystallisation occurs spontaneously such a process necessarily produces entropy causing the temperature to increase. Thus, the glassy and the crystalline state are not connected by an isothermal process, which is in contrast to the assumption in the classical nucleation and crystallisation theory as well as in the arguments causing Kauzmann's paradox. For the temperature T → 0K the enthalpy and entropy of the glass are larger by ΔH0 and ΔS0 as compared to the stable crystal. The calculations are illustrated using experimental data for quartz and silica glass from P. Richet, Y. Bottinga, L. Deniélou, J. P. Petitet and C. Téqui.

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Thermodynamics and Kinetics of Glass

Conradt¹

2019

Springer Handbook of Glass

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Non-equilibrium entropy of glasses formed by continuous cooling

Cited by 13 publications

References 53 publications

Melting and glass transition as mixing processes

Melting and glass transition as mixing processes

Energy and entropy of crystals, melts and glasses or what is wrong in Kauzmann's paradox?

Thermodynamics and Kinetics of Glass

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