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

Research output: Contribution to journalArticle

106 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(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.

Original languageEnglish (US)
Pages (from-to)6408-6415
Number of pages8
JournalJournal of Chemical Physics
Volume108
Issue number15
DOIs
StatePublished - Apr 15 1998
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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