Download Dielectric properties of critical conducting mixtures

Dielectric properties of critical conducting mixtures
Kazimierz Orzechowski
Faculty of Chemistry, Wrocław University Joliot-Curie 14, Wrocław, Poland
E-mail: [email protected]
The critical mixing point of binary liquids is a continuos phase transition and belongs to
[3,1] universality class. Large fluctuations of concentration and density close to Tc and xc
(critical temperature and concentration respectively) impede macroscopic properties of the
mixtures. In this lecture the dielectric properties - dielectric permittivity, conductivity and
non-linear dielectric effect will be presented in pure binary mixtures and in mixtures doped by
small amounts of ionic ingredients. Interesting properties related to the existence of ions
capable to migrating in microscopically inhomogeneous systems are expected and were
found. It will be presented the electric permittivity in and conductivity of alcohol +
hydrocarbon mixtures (also doped by ionic salts) in vicinity of the consolute critical point.
The observed low frequency dispersion was explained by Maxwell-Wagner phenomena in a
mixture with large concentration fluctuations. The generalised equations describing (t) and
(t) both in low and high frequencies were proposed and tested. Formal similarity between
critical mixtures and micro-emulsions was proved.
New results of the investigations of non-linear dielectric effect in mixtures doped by small
amounts of ionic salts will be presented. A special attention will be devoted to the properties
of doped critical mixtures investigated by the non-linear dielectric effect. The electric
conductivity obtained in strong electric field in the vicinity of critical mixing point will be
also discussed.