Corresponding states of order parameter in nematic liquid crystals

Abstract

In this work, experimental data points from which the profile of the order parameter of nematic liquid crystals can be obtained, mainly magnetic susceptibility anisotropy and dielectric anisotropy, will be used to show that when rescaled they coalesce along a common line that extends from the nematic-isotropic phase transition region, until the nematic-crystalline phase transition region. A large set of experimental data of a diversity of nematic compounds that share the presence of a nematic-isotropic and a nematic-crystalline phase transition, without another phase within, has been collected from the liquid crystals literature. Taking for each of them the temperatures of these two phase transitions as fixed points, a common temperature scale has been constructed and, in this scale, the value of each physical quantity has been uniformly fixed at the nematic-crystalline phase transition temperature. This procedure has revealed the existence of a law of corresponding states that covers the entire nematic phase. As the values assumed by these physical quantities can be used to measure the macroscopic order parameter, the use of this temperature scale suggests that it presents a common behavior that covers the entire nematic phase.