Reentrant Ferroelectricity in Liquid Crystals

Reentrant ferroelectricity in liquid crystals.

The ferroelectric (Sm C*)-antiferroelectric (Sm C*A)-reentrant ferroelectric (re Sm C*) phase temperature sequence was observed for systems with competing synclinic-anticlinic interactions. The basic properties of this system are as follows: (i) the Sm C* phase is metastable in the temperature range of the Sm C*A; (ii) the helix handedness inverts at both Sm C*-Sm C*A and Sm C*A-re-Sm C* phase ...

Molecular theory of proper ferroelectricity in bent-core liquid crystals.

Antiferro- and ferro-electric ordering has been discovered in orthogonal smectic phases composed of nonchiral bent-core molecules. These systems are the only proper fluid ferroelectrics confirmed experimentally so far. We consider a molecular theory of proper ferroelectric ordering in isotropic, nematic and smectic A phases and conclude that the delicate balance between the tendencies for local...

Ferroelectricity in low-symmetry biaxial nematic liquid crystals.

Order parameters and phenomenological theory for both high- and low-symmetry biaxial nematic phases are presented and it is predicted that the chiral low-symmetry biaxial phase must be ferroelectric. This conclusion is based on general symmetry arguments and on the results of the Landau-de Gennes theory. The microscopic mechanism of the ferroelectric ordering in this chiral biaxial phase is ill...

Ferroelectricity in Simple Binary Crystals

The origin of ferroelectricity in doped binary crystals, Pb1−xGexTe, Cd1−xZnxTe, Zn1−xLixO, and Hf1−xZrxO2 is discussed, while no binary ferroelectrics have been reported except for two crystals, HCl and HBr. The ferroelectricity is induced only in doped crystals, which shows an importance of electronic modification in chemical bonds by dopants. The phenomenological and microscopic treatments a...

Dielectric relaxation in liquid crystals exhibiting a reentrant phenomenon