The strong temperature dependent goldstone mode relaxation frequency in a broad range SmC* phase

Abstract

Broad frequency range dielectric spectroscopy, X-ray diffraction, electro-optical methods and thermal analysis are used to characterize a single component liquid crystal with a monotropic broad range room temperature ferroelectric SmC* phase. The dielectric spectrum shows a Soft mode and a Goldstone mode. Unlike in other ferroelectric liquid crystals the Goldstone mode of this substance has a strongly temperature dependent characteristic frequency. It is proposed that glassy-state fluctuations are responsible for the appreciable increase of activation energy (from 37 to 91 kJ/mol) upon cooling from 318 K (T_CA) to 278 K. Beside these modes a Domain mode is detected. Measurements in the high frequency range 1 MHz to 450 GHz show an additional relaxation process.