Thermodynamic investigation of phases transition in antiferrolectric liquid crystals: Theory and experiment

In this work, a theoretical model is developed, to investigate in more detail the electric field-temperature phase diagram (E-T) of antiferroelectric liquid crystals. The analysis shows that it is possible to obtain a complete description of the induced electric field transition of this material to deduce the entropies, nature of transition, enthalpies versus transition temperatures and transition electric field. Therefore, a quantitative and qualitative analysis of (E-T) phase diagram for some compounds is given. In addition, the constant current technique shows a significant increase of the cell voltage above the threshold near the electric induced (SmC*A-ferrielectric) transition. This behavior, which appears to be rather similar to the supercooled liquids near glass transition, is also discussed in the present work.