Dielectric relaxation spectroscopy of guest–host ferroelectric liquid crystals: influence of anthraquinone dye

Modification of electro-optical properties of an orthoconic chiral biphenyl smectogen with its isostructural carborane analogue

“…These results are consistent with the theory 54,55 and general behavior of SmC* mixtures. [56][57][58][59] The Cole-Cole analysis of the dielectric results recorded in a broad temperature range for the pure host 1F and the two solutions with 2F demonstrated only a single dielectric mode, the so-called Goldstone mode, present in the SmC* phase. 50 A plot of the imaginary part of the perpendicular component of the dielectric permittivity tensor 3 t 00 in a 10 Hz-10 MHz frequency domain recorded at DT ¼ À20 K showed that the maximum of dielectric loss observed for the pure host 1F at about 1 kHz was shifted to higher frequencies and its amplitude decreased upon addition of carborane derivative 2F (Fig.…”

“…60 Similar changes in the dielectric loss spectra were observed for other SmC* mixtures such as solutions of dichroic dyes in SmC* hosts. [56][57][58][59] The observed Wagner-Maxwell mode 55 in the low frequency region of the 20 mol% solution is due to ion conduction activated most likely by poor alignment uniformity and multi-domain structure of the sample. 55 The dielectric data allowed for the calculation of the relaxation frequency f r and dielectric strength D3 G ¼ 3 0 À 3 N from the Cole-Cole plots for each temperature, and results are shown in Fig.…”

Effect of Cell Thickness on the Dielectric Relaxation Processes in Ferroelectric Liquid Crystals

“…11 Majumdar et al reported the appearance of an unknown mode due to various defects in the sample cell configurations. 12 Results of dielectric relaxation mechanisms in guest-host (dye doped) FLC mixtures have been recently reported by Raina et al 13,14 and Kundu et al 15 They found that the dielectric spectrum in such systems consists of GM, a new relaxation mode (NRM) in SmC * phase and a soft mode in the vicinity of T C * A (SmC * -SmA transition temperature).…”

Dielectric and Electrical Investigations in Pure and Dyed Short Pitch High Spontaneous Polarization Liquid Crystals

“…In the SmA Ã phase, however, the contribution to permittivity is only from soft mode. Recently, some more relaxation modes, namely, bulk domain mode (BDM) and new relaxation mode (NRM), have also been reported in ferroelectric liquid crystal mixtures in the SmC Ã phase [10][11][12][13][14][15][16]. These modes appear in the presence of an external electric field [16].…”