Dynamics of glass-forming liquids. IV. True activated behavior above 2 GHz in the dielectric α-relaxation of organic liquids

C. Hansen; F. Stickel; R. Richert; E. W. Fischer

doi:10.1063/1.476063

Dynamics of glass-forming liquids. IV. True activated behavior above 2 GHz in the dielectric α-relaxation of organic liquids

C. Hansen, F. Stickel, R. Richert, E. W. Fischer

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110 Scopus citations

Abstract

We have measured the dielectric relaxation of butylbenzene and of the glass-former propylbenzene in the frequency range 10^-2 Hz to 2×10¹⁰ Hz in order to characterize the variation of relaxation times with temperature for these low loss liquids. Additionally, salol has been remeasured above 1 GHz with improved resolution. Using the sensitive data representation [-d log₁₀(f_maxHz)/ d(1/T)]^-1/2 vs 1/T we find demarcation temperatures T_A, at which the temperature dependence changes from a Vogel-Fulcher type law within the limits T_B≤T≤T_A to Arrhenius behavior for T>T_A, corresponding to a position of the loss peak f_max>2 GHz. The activation energies derived from dielectric relaxation data for T>T_A are associated with the energy of vaporization, E^η ∝ΔE_vap. A comparison of dielectric relaxation times τ_D to viscosity data in this wide range of temperatures suggests the relation τ_D∝η/T rather than τ_D∝η.

Original language	English (US)
Pages (from-to)	6408-6415
Number of pages	8
Journal	Journal of Chemical Physics
Volume	108
Issue number	15
DOIs	https://doi.org/10.1063/1.476063
State	Published - Apr 15 1998
Externally published	Yes

ASJC Scopus subject areas

General Physics and Astronomy
Physical and Theoretical Chemistry

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title = "Dynamics of glass-forming liquids. IV. True activated behavior above 2 GHz in the dielectric α-relaxation of organic liquids",

abstract = "We have measured the dielectric relaxation of butylbenzene and of the glass-former propylbenzene in the frequency range 10-2 Hz to 2×1010 Hz in order to characterize the variation of relaxation times with temperature for these low loss liquids. Additionally, salol has been remeasured above 1 GHz with improved resolution. Using the sensitive data representation [-d log10(fmaxHz)/ d(1/T)]-1/2 vs 1/T we find demarcation temperatures TA, at which the temperature dependence changes from a Vogel-Fulcher type law within the limits TB≤T≤TA to Arrhenius behavior for T>TA, corresponding to a position of the loss peak fmax>2 GHz. The activation energies derived from dielectric relaxation data for T>TA are associated with the energy of vaporization, Eη ∝ΔEvap. A comparison of dielectric relaxation times τD to viscosity data in this wide range of temperatures suggests the relation τD∝η/T rather than τD∝η.",

author = "C. Hansen and F. Stickel and R. Richert and Fischer, {E. W.}",

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AU - Hansen, C.

AU - Stickel, F.

AU - Richert, R.

AU - Fischer, E. W.

PY - 1998/4/15

Y1 - 1998/4/15

N2 - We have measured the dielectric relaxation of butylbenzene and of the glass-former propylbenzene in the frequency range 10-2 Hz to 2×1010 Hz in order to characterize the variation of relaxation times with temperature for these low loss liquids. Additionally, salol has been remeasured above 1 GHz with improved resolution. Using the sensitive data representation [-d log10(fmaxHz)/ d(1/T)]-1/2 vs 1/T we find demarcation temperatures TA, at which the temperature dependence changes from a Vogel-Fulcher type law within the limits TB≤T≤TA to Arrhenius behavior for T>TA, corresponding to a position of the loss peak fmax>2 GHz. The activation energies derived from dielectric relaxation data for T>TA are associated with the energy of vaporization, Eη ∝ΔEvap. A comparison of dielectric relaxation times τD to viscosity data in this wide range of temperatures suggests the relation τD∝η/T rather than τD∝η.

AB - We have measured the dielectric relaxation of butylbenzene and of the glass-former propylbenzene in the frequency range 10-2 Hz to 2×1010 Hz in order to characterize the variation of relaxation times with temperature for these low loss liquids. Additionally, salol has been remeasured above 1 GHz with improved resolution. Using the sensitive data representation [-d log10(fmaxHz)/ d(1/T)]-1/2 vs 1/T we find demarcation temperatures TA, at which the temperature dependence changes from a Vogel-Fulcher type law within the limits TB≤T≤TA to Arrhenius behavior for T>TA, corresponding to a position of the loss peak fmax>2 GHz. The activation energies derived from dielectric relaxation data for T>TA are associated with the energy of vaporization, Eη ∝ΔEvap. A comparison of dielectric relaxation times τD to viscosity data in this wide range of temperatures suggests the relation τD∝η/T rather than τD∝η.

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Dynamics of glass-forming liquids. IV. True activated behavior above 2 GHz in the dielectric α-relaxation of organic liquids

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