High temperature antiferroelectric smectic phase composed of banana-shapedachiral molecules

In this paper a report is given on a fluorinated compound, composed of bana na-shaped molecules showing antiferroelectric behavior in the high temperat ure smectic Bz phase. Dielectric studies performed in the frequency range b etween 10 Hz and 13 MHz revealed two broad peaks in the low frequency diele ctric spectrum of B2 phase. There is only one complex relaxation process in the B-1 phase that transforms into a glassy state where the molecular proc ess responsible for the dielectric spectrum is being frozen out. The Vogel- Fulcher model has been applied to describe temperature dependence of the re laxation time in the vicinity of the glassy transition that is characterize d by T-o = 303.95 K and Tg = 316.46 K. At the end some possible mechanisms of dielectric relaxation processes observed will be discussed. Spontaneous polarization computed by integrating of the polarization current peaks is e qual to ca. 400 nC/cm(2) for the B-2 phase.