Complementary studies of BaTiO

In scope of this paper, DSC, small-angle X-ray scattering (SAXS), electro-optic and dielectric studies have been done on BaTiO3 nanoparticles dispersed in a ferroelectric liquid-crystalline (FLC) matrix. Electro-optic studies showed slightly lower spontaneous polarization, faster response time and relatively higher coercive voltage for the nanocomposite as compared to the pure FLC mixture. Dielectric measurements revealed a lower relative dielectric permittivity for the nanocomposite. This paper addresses all the issues starting from the kind of nanoparticles and FLC materials used for the preparation of nanocomposites, the various measurements done and a detailed discussion on the observed results

Dielectric and Conductivity Anisotropy in Liquid Crystalline Phases of Strongly Polar Thioesters

The main objective of this paper is to study dielectric properties of two compounds of acronyms 5OSCl and 6OSCl having strongly polar bond (C-Cl) at para position. Dielectric measurements were done in the frequency range from 40 Hz to 15 MHz. The dielectric spectra were measured for two principal alignments. For homeotropic alignment, the reorientation of molecule around the short molecular axis was observed. Both substances studied exhibit large positive dielectric anisotropy and the anisotropy of conductivity was obtained in smectic A as well as nematic phase

Dielectric and Electrooptic Investigations of B Phases οf Banana-Shaped Thioesters

Electrooptic and dielectric measurements were done for B phases of two banana-shaped homologues 1,3-phenylene bis{4-[(4-nonylo-xy-benzoyl)sulfanyl]benzoate (9OSOR) and 1,3-phenylene bis{4-[(4-dodecylo-xy-benzoyl)sulfanyl]benzoate (12OSOR). Polarizing microscopy allowed to identify $B_{1}$ phase for 9OSOR and $B_{2}$ phase for 12OSOR on the basis of texture observation. Spontaneous polarization measurements were performed using reversal current method. The current response to applied triangular voltage shows that $B_{1}$ phase is a ferroelectric and $B_{2}$ phase - antiferroelectric one for which two well separated peaks were observed. Polarization for phase $B_{1}$ of 9OSOR is rather small and its temperature dependence is unusual for ferroelectric liquid crystals - it increases with temperature. Spontaneous polarization for $B_{2}$ phase of 12OSOR compound is of about 600 nC/$cm^{2}$. Dielectric spectra measured with bias field for $B_{2}$ phase of 12OSOR show two well separated relaxation processes. In the low frequency range the relaxation process is connected with fluctuations of ferroelectric domains. The relaxation process in the high frequency range appearing also without bias field is connected with molecular reorientation. The dielectric spectra measured for $B_{1}$ phase of 9OSOR with and without bias voltage showed only one dielectric relaxation process connected with molecular reorientation around the short axis