Project: Dielectric Relaxation |
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With various experimental techniques, we are studying the dielectric properties of liquids, supercooled liquids, polymers, and glasses [47, 51, 60, 69, 77, 79, 85, 88, 97, 107]. The dielectric polarization measured as e* (w) and as M*(w) lead to curves which differ in the characteristic time scales and in the way they are affected by electrode polarization [75, 84]. However, the information regarding the motion of dipoles and ions is independent of the applied method [103]. |
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Schematic comparison of the dielectric function e*
(w) with its equivalent modulus M*(w).
All curves are based upon the same dielectric properties:
an exponential relaxation process and a low dc- conductivity. |
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Our interest here is to understand the temperature dependence of the relaxation times and its relation to the distribution of relaxation times and to dynamic heterogeneity. We are exploring the dielectric behavior of materials with extremely low dielectric loss, like decalin [107], squalane [111], aab-tris-naphthylbenzene [111], and o-terphenyl [132, 141]. |
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Master plot of the dielectric loss e''(w) of neat cis/trans-decahydro-naphthalene (DHN)
versus reduced frequency f/fmax in the range 10-2
£ f/fmax £ 106. The data are derived from measurements taken at temperatures
in the range 138 K £ T £
150 K, in steps of 2 K. In this series of experiments, the loss tangent tand remains below 6´10-4.
[107] |
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Reference numbers refer to the list of publications |
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Experimental techniques:
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Selected projects:
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