On the critical behavior of linear and nonlinear dielectric permittivity on approaching the critical consolute point

Results are presented of the dielectric permittivity (epsilon) and nonlinear dielectric effects (NDE) in binary mixtures on approaching the critical consolute point (CCP), focusing first on Piekara's findings [Phys. Rev. Vol.42, pp. 445-447, 1932, and C. R. Acad. Sci. Paris Vol. 203, pp. 1058-1059, 1936]. The presented results cover changes in temperature and pressure. For NDE particular attention is given to complex liquid features of critical mixtures appearing in epsilon and NDE tests. The latter are presented for the stationary and dynamic (time-resolved NDE) behavior. New results for NDE in nitrobenzene, hexane mixture with the lowest measurement frequency ever applied and in benzonitrile-isooctane mixture for dielectric permittivity are also included. For the latter, the first test of the relation: depsilon/dT alpha (T - T-C)(-alpha) is shown.