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Temperature, concentration, and frequency dependence of the dielectric constant near the critical point of the binary liquid mixture nitrobenzene-tetradecane

par Leys, Jan;Losada Perez, Patricia ;Cordoyiannis, George;Cerdeirina, CA;Glorieux, Christ;Thoen, Jan
Référence The Journal of Chemical Physics, 132, page (104508)
Publication Publié, 2010-03-14

Article révisé par les pairs

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Résumé :

Detailed results are reported for the dielectric constant ϵ ϵ as a function of temperature, concentration, and frequency near the upper critical point of the binary liquid mixture nitrobenzene-tetradecane. The data have been analyzed in the context of the recently developed concept of complete scaling. It is shown that the amplitude of the low frequency critical Maxwell–Wagner relaxation (with a relaxation frequency around 10 kHz) along the critical isopleth is consistent with the predictions of a droplet model for the critical fluctuations. The temperature dependence of ϵ ϵ in the homogeneous phase can be well described with a combination of a (1−α) (1−α) power law term (with α α the heat capacity critical exponent) and a linear term in reduced temperature with the Ising value for α α . For the proper description of the temperature dependence of the difference Δϵ Δϵ between the two coexisting phases below the critical temperature, it turned out that good fits with the Ising value for the order parameter exponent β β required the addition of a corrections-to-scaling contribution or a linear term in reduced temperature. Good fits to the dielectric diameter ϵd ϵd require a (1−α) (1−α) power law term, a 2β 2β power law term (in the past considered as spurious), and a linear term in reduced temperature, consistent with complete scaling.