Harvested and non-harvested tin thiohypodiphosphate (Sn₂P₂S₆) ferroelectric nanoparticles are used to dope the 4-n-octyl-4′-cyanobiphenyl liquid crystal (8CB). Due to their higher average spontaneous polarization, the harvested nanoparticles have stronger interactions with the liquid crystal molecules which leads to a higher order parameter as demonstrated by the increase in phase transition temperatures. This is confirmed by the results of dielectric characterization. In the homeotropic orientation, the increase in the order parameter leads to a higher dielectric permittivity. In the planar orientation, the coupling between the spontaneous polarization of the nanoparticles and the order parameter induces a slight reorientation of the liquid crystal director from the initial planar orientation, leading to an increase in the dielectric permittivity. This effect is more important for the liquid crystal doped with harvested nanoparticles.

We have performed dielectric measurements in the S*_Cα phase of an antiferroelectric liquid crystal. Without superimposition of a DC bias, one relaxation process is detected in this phase. This process goes continuously from the S_A soft mode to the S* _C Goldstone mode, with linear temperature dependence of the reversed dielectric strength and of the critical frequency. The S* _Cα phase is clearly detected since a break in slopes is observed at the S_A - S* _Cα and the S*_Cα-S* _C phase transitions. This relaxation process is connected with the helicity of the S* _Cα phase since it is strongly modified under bias. At high bias, one relaxation process is also observed which behavior is similar to that of the soft mode at a S_A-S* _C phase transition.

Two thioester compounds: (S)-(+)-4-(1-methylheptyloxy)biphenyl 4′-heptylthiobenzoate (in short: MHOBS7) having rode-like, calamitic-chiral molecules, and 1,3-phenylene bis{4-[(4-octyloxybenzoyl)-sulfanyl]benzoate} (in short: 8OSOR) built of banana like achiral molecules, have been studied by complementary methods to show differences in their linear dielectric as well as ferroelectric properties. To this end the following experimental methods were used: differential scanning calorimetry, polarizing microscopy, dielectric spectroscopy and reversal current method. The first compound shows a ferroelectric SmC* phase with temperature dependent Goldstone mode displaying negative activation energy. At the N*--SmC* transition spontaneous polarization changes discontinuously showing first order character of this transition. For 8OSOR compound with bent core molecules only B₁ phase shows up, which does not switch. However, it was possible to record reversal current spectra but temperature dependence of spontaneous polarization was unusual suggesting antiferroelectric order of this phase.

In this article the physical properties of hexatic phases of three substances MHPNBC, FOOPP and FNHPP have been studied by differential scanning calorimetry, texture observation and dielectric spectroscopy. Experimental results are discussed from the point of view of existing theories. It is interesting that two of the substances studied, the FOOPP and FNHPP, exhibit enhanced spontaneous polarization in the highly ordered SmI* phase and show a jump of the spontaneous polarization in the vicinity of the SmC*–SmI* transition. In the SmI* phase of FOOPP a very high value of spontaneous polarization of the order of 530 nC cm⁻² was found. Based on the results obtained the macroscopic and microscopic properties of the hexatic phases are discussed.

The temperature dependence of the ionic conductivity is studied in a series of poly(propylene glycol) diacrylate monomers. The experimental data are analyzed by means of the approach recently proposed by Petrowsky et al. [ J. Phys. Chem. B. 113, 5996 (2009)]. This so-called compensated Arrhenius formalism (CAF) approach takes into account the influence of the dielectric permittivity on the exponential prefactor in the classical Arrhenius equation. The experimental data presented in this paper show a good agreement with the CAF; this means that the exponential prefactor is principally dielectric permittivity dependent. The compensated data revealed two conduction processes with different activation energies; they correspond to low and high temperature ranges, respectively.