Molecular–Statistical Theory for the Description of Re-Entrant Ferroelectric Phase

Abstract

The re-entrant ferroelectric phase (Sm- C re * ) is investigated in the framework of a molecular–statistical approach. It was found that anticlinic synpolar along the smectic layer normal phase can arise below the antiferroelectric phase (Sm- C A * ) in the temperature scale, and we suggest this phase to be Sm- C re * . We have shown that in the vicinity of Sm- C A * –Sm- C re * phase transition temperature, a very small electric field can cause a transition into the bidomain synclinic phase, where the helical pitch is unwound and the tilt planes have contributions either along or against the electric field. The helical rotation, elasticity and deformation of the Sm- C * , Sm- C A * and Sm- C re * structures without electric field or in the presence of electric field, as well as the dielectric response, are investigated. It is shown that Sm- C re * can arise solely due to the dipole–dipole interaction, and thus, in contrast to the conventional (improper) ferroelectric Sm- C * , appears to be the proper ferroelectric phase.