Dielectric characterisation of a ferroelectric liquid crystalline material having SmA*–SmC*–SmB_h* phase sequence

Abstract

Thermodynamical, optical and dielectric characterisation of a material possessing ferroelectric SmC* and hexatic SmB* phases has been carried out. Phase identification has been done by miscibility studies. From the dielectric studies, a relaxation mechanism is observed in the low MHz region of the SmA* phase, which is related to the tilt fluctuation (soft mode) of the directors. In the SmC* phase, another collective relaxation mechanism has been observed in the kHz region, which is related to the phase fluctuation (Goldstone mode) of the directors. In the SmB_h* phase, 2-weak relaxation modes are observed in the kHz and MHz frequency range, respectively, due to individual molecular rotations.

Keywords:

• ferroelectric liquid crystals
• dielectric spectroscopy
• relaxation mechanism
• Goldstone mode
• soft mode
• miscibility studies

Acknowledgements

The authors thank Dr Damian Pociecha from Faculty of Chemistry, University of Warsaw, for X-ray measurement.