EPJ E Topical review - Liquid-liquid criticality in the dielectric constant and refractive index: A perspective

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Published on 27 August 2019

The critical region in the phase diagram of condensed matter systems such as fluids or fluid mixtures is characterized by the anomalous behaviour of specific thermodynamic properties. In a new review article published in EPJE, Patricia Losada-Pérez (Department of Physics, Université Libre de Bruxelles) describes recent progress in the understanding of the behaviour of two intimately related properties, the dielectric constant ε and the refractive index n, when approaching the liquid-liquid critical point in binary liquid mixtures.

Phenomenological scaling approaches, in particular complete scaling formulation, are highlighted, and experimental evidence provided by dielectric spectroscopy and optical measurements supporting the asymmetry-related critical features in ε and n in the one and two-phase regions is assessed. The article revisits recent experimental data and points out the peculiar patterns of behaviour of polar-polar liquid mixtures as compared to (much more frequently studied) polar-non polar mixtures, and highlights the necessity for future research efforts in the study of polar-polar mixtures, which would shed light into the influence of (microscopic) system-dependent parameters on asymmetry-related features of liquid-liquid criticality.

This review is part of the Topical Issue on Dielectric Spectroscopy Applied to Soft Matter.