Stable field-induced ferrielectric liquid crystal phases in devices

The field-induced transitions between ferri-, antiferro-, and ferroelectric liquid crystal phases are interesting because although there are only small thermodynamic differences between them, each of these phases has different electrical and optical properties. We report an irreversible field-induced transition from an antiferroelectric phase to the ferrielectric phase in a liquid crystal device, and compare it to a system in which the transition is reversible. The two systems differ mainly in their spontaneous polarization (120 nC cm-2 for the former and 60 nC cm-2 for the latter) while the optical tilt is comparable (29° and 25°, respectively). We explain the observed transitions based on the relative magnitudes of the discrete flexoelectric and spontaneous polarizations. © 2009 American Institute of Physics.