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.