Antiferroelectric Chiral Smectic Phases Responsible for the Trislable Switching in MHPOBC

Abstract

At least two antiferroelectric liquid crystalline phases were discovered in MHPOBC. These phases appear below the usual ferroelectric Sm C* phase. Because of the alternation of the molecular tilt directions as well as the dipole orientations in successive layers, the optic axis is along the layer normal. This strong stabilization along the layer normal brings about the so-called third stable state responsible for the tristable switching. The antiferroelectric structure was strongly supported by selective reflections in oblique incidence; a full-pitch band does not appear in the antiferroelectric phases, while it does appear in the ferroelectric phase.

Chiral Liquid Crystals: Structures, Phases, Effects

“…Having demonstrated the occurrence of a spontaneous polarization and the property of ferroelectricity for the chiral, tilted SmC* phase, it should be noted that also other similarities to solid state materials can be observed, namely antiferroelectric [97][98][99] and intermediate [100,101] structures. Just like their ferroelectric counterpart, the former exhibit a helical superstructure, which for now we neglect for reasons of clarity.…”

Cristais Líquidos Ferroelétricos - CLF. Uma abordagem sintética

“…A pesquisa nesta nova frente, sob o ponto de vista acadêmico e de aplicação tecnológica, tem avançado significativamente. Como exemplo representativo, o composto MHPOBC -metilheptil p-noctilbifenilcarboxilato 44 , descrito abaixo, apresenta duas novas fases intermediárias entre as mesofases S A e S C * e entre as S C * e S CA * (S CA * = mesofase anti-ferroelétrica), denominadas de S C *α e S C *γ, respectivamente 45,46 . A definição de mesofase ferri e antiferroelétrica está relacionada com a estrutura macromolecular da mesofase S C quiral.…”

Electrophysical properties of a system with induced antiferroelectric phase comprising cyano compound

“…The antiferroelectric smectic phase was observed for the first time by Górecka, Chandani, and Fukuda in MHPOBC [1]. Since the discovery of antiferroelectricity in liquid crystals, a great number of different structures showing the smectic SmC* A phase have been prepared [2].…”