High-resolution calorimetric study of phase transitions in chiral smectic-C liquid crystalline phases

We carried out an improved characterization of phase transitions among chiral smectic-C subphases observed for various antiferroelectric liquid crystals by precise heat capacity measurements. It was found that the phase transitions are intrinsically first order exhibiting a remarkable heat anomaly which involves little pretransitional thermal fluctuation and a finite thermal hysteresis. On the other hand, we also noticed that the critical point of the smectic-Cα*-smectic-C^* transition is induced by the destabilization of the smectic-Cα* phase which couples with the fluctuation associated with the smectic-A-smectic-Cα* phase transition.