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

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.

Editors-in-Chief
Pere Roca i Cabarrocas and Daniel Lincot
ISSN: 2105-0716 (Electronic Edition)

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