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Título:
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Nature and properties of the Johari-Goldstein ?-relaxation in the equilibrium liquid state of a class of glass-formers
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Autores:
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Ngai, K. L. ;
Lunkenheimer, P. ;
León Yebra, Carlos ;
Schneider, U. ;
Brand, R. ;
Lodl, A.
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Tipo de documento:
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texto impreso
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Editorial:
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American Institute of Physics, 2001-07-15
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Dimensiones:
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application/pdf
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Nota general:
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info:eu-repo/semantics/openAccess
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Idiomas:
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Palabras clave:
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Estado = Publicado
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Materia = Ciencias: Física: Electricidad
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Materia = Ciencias: Física: Electrónica
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Tipo = Artículo
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Resumen:
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Previous dielectric relaxation measurements of glycerol and propylene carbonate and new results on propylene glycol performed below the conventional glass transition temperatures T_(g) after long periods of aging all show that the excess wing (a second power law at higher frequencies) in the isothermal dielectric loss spectrum, develops into a shoulder. These results suggest that the excess wing, a characteristic feature of a variety of glass-formers, is the high frequency flank of a Johari–Goldstein ?-relaxation loss peak submerged under the ?-relaxation loss peak. With this interpretation of the excess wing assured, the dielectric spectra of all three glass-formers measured at temperatures above T_(g) are analyzed as a sum of a ?-relaxation modeled by the Fourier transform of a Kohlrausch–Williams–Watts function and a ?-relaxation modeled by a Cole–Cole function. Good fits to the experimental data have been achieved. In addition to the newly resolved ?-relaxation on propylene glycol, the important results of this work are the properties of the ?-relaxation in this class of glass-formers in the equilibrium liquid state obtained over broad frequency and temperature ranges.
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En línea:
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https://eprints.ucm.es/id/eprint/31104/1/LeonC95libre.pdf
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