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Titolo:
A method to determine the kinetics of a supercooled liquid by temperature scanning measurements applied to (Li,Na)acetate and GeO2
Autore:
Bruning, R; Crowell, T;
Indirizzi:
Mt Allison Univ, Dept Phys Engn & Geosci, Sackville, NB E4L 1E6, Canada MtAllison Univ Sackville NB Canada E4L 1E6 Sackville, NB E4L 1E6, Canada
Titolo Testata:
JOURNAL OF NON-CRYSTALLINE SOLIDS
fascicolo: 2-3, volume: 248, anno: 1999,
pagine: 183 - 193
SICI:
0022-3093(199906)248:2-3<183:AMTDTK>2.0.ZU;2-W
Fonte:
ISI
Lingua:
ENG
Soggetto:
GLASS-TRANSITION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
18
Recensione:
Indirizzi per estratti:
Indirizzo: Bruning, R Mt Allison Univ, Dept Phys Engn & Geosci, 67 York St, Sackville, NB E4L 1E6, Canada Mt Allison Univ 67 York St Sackville NB Canada E4L 1E6, Canada
Citazione:
R. Bruning e T. Crowell, "A method to determine the kinetics of a supercooled liquid by temperature scanning measurements applied to (Li,Na)acetate and GeO2", J NON-CRYST, 248(2-3), 1999, pp. 183-193

Abstract

Temperature scanning techniques are frequently used to measure glass transitions. For such a measurement, the width of the glass transition regime depends on the fragility of the substance. This paper discusses the degree towhich the transition regime becomes smaller when the temperature scan-rateis decreased. Based on the general properties of supercooled liquids it isshown that this decrease may vary by a factor of two, from the most strongto the most fragile substances. To test this prediction, scanning calorimetry data are reported for germanium oxide, a strong glass-forming system, and (Li,Na)acetate, a fragile system. By considering the scanning rate dependence of the width, the second derivative of the glass temperature with respect to the relaxation time can be determined from the data. The parametersof the Vogel-Fulcher equation can be specified with this result from temperature scanning data alone, and the numerical results are compared with equilibrium viscosity measurements. The method demonstrated here to determine the kinetic parameters of a supercooled liquid is well suited for a regime of longer relaxation times, whereas in the case of a constant temperature experiment it is difficult to ensure that a sample is in thermal equilibrium. (C) 1999 Elsevier Science B.V. All rights reserved.

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Documento generato il 09/08/20 alle ore 23:20:20