Dielectric properties of TGB_A and TGB_C phases

Abstract

The dielectric properties of two compounds displaying N*-TGB_A-S_C* or N*-TGB_A-TGB_C-S_C* phase sequences have been studied. A simplified model based on a TGB_C structure established from previous X-ray and optical works is also proposed. The observed relaxation processes are attributed to the Goldstone and the soft modes. The amplitudes (resp. frequencies) are low (resp. high), especially for the Goldstone mode. This is explained by elastic distortions due to the existence of grain boundaries, these distortions being very dependent on the block size.

Keywords:

• Dielectric
• Ferroelectric liquid crystal
• soft mode
• Goldstone mode
• Twist Grain Boundaries phases