Losada-Pérez Patricia, Pérez-Sánchez Germán, Cerdeiriña Claudio A, Thoen Jan
Departamento de Física Aplicada, Universidad de Vigo, As Lagoas s/n, Ourense 32004, Spain.
Phys Rev E Stat Nonlin Soft Matter Phys. 2010 Apr;81(4 Pt 1):041121. doi: 10.1103/PhysRevE.81.041121. Epub 2010 Apr 20.
The behavior of the dielectric constant epsilon of pure fluids and binary mixtures near liquid-gas and liquid-liquid critical points is studied within the concept of complete scaling of asymmetric fluid-fluid criticality. While mixing of the electric field into the scaling fields plays a role, pressure mixing is crucial as the asymptotic behavior of the coexistence-curve diameter in the epsilon-T plane is concerned. Specifically, it is found that the diameters, characterized by a |T-Tc|1-alpha singularity in the previous scaling formulation [J. V. Sengers, D. Bedeaux, P. Mazur, and S. C. Greer, Physica A 104, 573 (1980)], gain a more dominant |T-Tc|2beta term, whose existence is shown to be supported by literature experimental data. The widely known |T-Tc|1-alpha singularity of epsilon along the critical isopleth in the one-phase region is found to provide information on the effect of electric fields on the liquid-liquid critical temperature: from experimental data it is inferred that Tc usually decreases as the magnitude of the electric field is enhanced. Furthermore, the behavior of mixtures along an isothermal path of approach to criticality is also analyzed: theory explains why the observed anomalies are remarkably higher than those associated to the usual isobaric path.
在非对称流体 - 流体临界性完全标度的概念下，研究了纯流体和二元混合物在液 - 气及液 - 液临界点附近的介电常数ε的行为。虽然将电场混入标度场会起作用，但就ε - T平面中共存曲线直径的渐近行为而言，压力混合至关重要。具体而言，发现先前标度公式[J. V. 森格斯、D. 贝德奥克斯、P. 马祖尔和S. C. 格里尔，《物理学报A》104, 573 (1980)]中以|T - Tc|1 - α奇异性表征的直径，获得了一个更占主导的|T - Tc|2β项，文献实验数据表明该项的存在是有依据的。发现在单相区域中沿着临界等压线的ε的广为人知的|T - Tc|1 - α奇异性提供了关于电场对液 - 液临界温度影响的信息：从实验数据推断，随着电场强度的增强，Tc通常会降低。此外，还分析了混合物沿着等温趋近临界路径的行为：理论解释了为何观察到的异常现象明显高于与通常等压路径相关的异常现象。
