The fluid-like and critical behavior of the isotropic-nematic transition appearing in linear and non-linear dielectric studies

A short review; of literature and the authors' experimental results for the pretransitional behavior in the isotropic phase of nematogens is given. Th e paper also presents new results of non-linear dielectric effect and diele ctric permittivity measurements in the broad temperature range. Results obt ained show significant advantages of non-linear dielectric effect and diele ctric permittivity for studying pretransitional properties in liquid crysta lline materials. The paper contains a comprehensive comparison of the exper iment with predictions of the mean-field model and the fluid-like descripti on. The presented analysis strongly supports the image of the isotropic pha se as a complex liquid resulting from vicinity of the fluid-like, "nematic- isotropic'', critical point.