paper

Prevalence of approximate square root t relaxation for the dielectric alpha process in viscous organic liquids

arXiv:0811.1116 · doi:10.1063/1.3098911

Abstract

This paper presents dielectric relaxation data for organic glass-forming liquids compiled from different groups and supplemented by new measurements. The main quantity of interest is the "minimum slope" of the dielectric loss plotted as a function of frequency in a log-log plot (i.e., the numerically largest slope above the loss peak frequency). The data consisting of 347 spectra for 53 liquids show prevalence of minimum slopes close to -1/2, corresponding to approximate square-root-time dependence of the dielectric relaxation function at short times. The paper further studies possible correlations between minimum slopes and: 1) Temperature quantified via the loss-peak frequency; 2) How well an inverse power law fits data above the loss peak; 3) Degree of time-temperature superposition; 4) Loss-peak half width; 5) Deviation from non-Arrhenius behavior; 6) Loss strength. For the first three points we find correlations that indicate a special status of liquids with minimum slopes close to -1/2. For the last three points only fairly insignificant correlations are found with the exception of large-loss liquids, which have minimum slopes that are numerically significantly larger than 1/2 and loss peak widths that are significantly smaller than those of most other liquids. We conclude that -- excluding large-loss liquids -- approximate relaxation appears to be a generic property of the relaxation of organic glass formers.

References in corpus (6)

Cited by in corpus (30)