Critical behavior of dielectric permittivity and electric conductivity in temperature and pressure studies above and below the critical consolute point

• Published in: The Journal of chemical physics 2003-05, Vol.118 (20), p.9357-9363
• Main Authors: Malik, P., Rzoska, S. J., Drozd-Rzoska, A., Jadżyn, J.
• Format: Article
• Language: English
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.1569241

Results of comprehensive temperature (T) and pressure (P) studies of static dielectric permittivity (ε′) and electric conductivity (σ) in the one- and two-phase regions of critical nitrobenzene–dodecane mixture are presented. A strong asymmetry of determined coexistence curves causes a strong violation of the law of rectilinear diameter. The obtained critical anomalies in the homogeneous phase [εhomo′(T),εhomo′(P),σhomo(P)] or the diameter of the binodal [εmean′(T),εmean′(P),σmean(T),σmean(P)] are associated with the same critical exponent φ=1−α ≈0.88, where α is the specific heat critical exponent. Critical anomalies for the isothermal, pressure path exhibit a set of favorite in comparison with results obtained in σ(T) and ε(T) tests. They are: the negligible influence of the critical Maxwell–Wagner effect, the hardly visible appearance of the correction-to-scaling term, a more pronounced manifestation of critical anomalies, and a reduced number of fitted parameters. Particularly noteworthy is the evidence for the σhomo(P) anomaly in the homogeneous phase, hardly obtained up to now in a mixture of a low electric conductivity. Results presented suggest the isomorphic behavior of ε′(T), σ(T) and ε′(P), σ(P) critical anomalies for the homogeneous phase and for the diameter of the binodal.