Dielectric Spectroscopy of the Fluorinated AFLC's and Their Protonated Analogs

Abstract

Dielectric measurements were performed for three representative with n = 2, 5 and 7 of series of three ring esters with perfluoroalkanoyloxyhexyloxy terminal chain and for their protonated analogs. Temperature dependences of relaxation frequency f _R and the inverse of dielectric strength 1/Δ ϵ′_⊥ were obtained by fitting experimental values perpendicular components: real ϵ′_⊥′ and imaginary ϵ′_⊥ parts of the complex dielectric permittivity ϵ′_⊥ to the Cole-Cole distribution. On based above results and taking into considerations temperature dependences of the spontaneous polarization, the tilt angle, the interlayer spacing and calculations of molecular structure of investigated compounds obtained by using Hyper Chem modelling software, one can conclude that for all compounds of both series molecules are already tilted in SmA* phase and dielectric soft mode absorption correlates with the degree of layer shrinkage.

Keywords:

• Smectics phases
• antiferroelectrics
• dielectric spectroscopy
• layer shrinkage