Electric field induced transformations and dielectric properties of ferrielectric smectic phase

Some of the antiferroelectric liquid crystal compounds (C12HH, C12F3 and MHPOBC) displaying ferrielectric phase are investigated. In a planar sample the ferrielectric (SmC*FI1) existing between the ferroelectric (SmC*) and the anticlinic (SmC*A) phases is suppressed due to an anchoring surface. In this configuration, we report the first observation of this phase by heating. Therefore, its properties are studied by dielectric, electro-optic and microscopic techniques. The experiments, mentioned above, suggest that SmC*A–SmC*FI1 transition is first order. The electric–temperature (E–T) phase diagram of the C12HH compound including the existence of induced intermediate phase is well established experimentally. At the same time, the electric–concentration (E–x) phase diagram is also determined in the intermediate phase of the mixtures formed from the enantiomers of the MHPOBC compound. This phase diagram shows a significant concentration dependence of induced phase stability and unwinding threshold.