| Autor: |
Nielsen, Albena I., Christensen, Tage, Jakobsen, Bo, Olsen, Kristine Niss Niels Boye, Richert, Ranko, Dyre, Jeppe C. |
| Rok vydání: |
2008 |
| Předmět: |
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| Zdroj: |
J. Chem. Phys. 130, 154508 (2009) |
| Druh dokumentu: |
Working Paper |
| DOI: |
10.1063/1.3098911 |
| Popis: |
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 $\alpha$ 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 $\sqrt t$ relaxation appears to be a generic property of the $\alpha$ relaxation of organic glass formers. |
| Databáze: |
arXiv |
| Externí odkaz: |
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