Showing papers by "Jan Jadżyn published in 1996"
TL;DR: In this article, nonlinear dielectric spectroscopy was used to study the selfassociation of 2-pyrrolidinone in benzene solutions up to 0.9 mol/L at 25 °C.
Abstract: Nonlinear dielectric spectroscopy is used to study the self-association of 2-pyrrolidinone in benzene solutions up to 0.9 mol/L at 25 °C. The nonlinear dielectric spectra below 100 MHz are recorded...
32 citations
TL;DR: The magnetic Fredericksz transition in a ferronematic (thermotropic nematic liquid crystal MBBA combined with fine magnetic particles of size 10 nm) has been studied as a function of the concentration of magnetic particles by means of simple dielectric measurements as mentioned in this paper.
14 citations
TL;DR: In this paper, the static permittivities and the dielectric spectra were measured for the following liquids in the pure state and in mixtures with 1,4-dioxane at 20 °C.
12 citations
TL;DR: In this article, the authors investigated the possible mechanisms responsible for two relaxation processes in both the isotropic and nematic phases, when the measurements of the electric permittivity versus frequency are made parallel to the orientation axis of the liquid crystal, and the height of the potential barrier which hinders the rotation of liquid crystal molecules around the short axis in the nematic state was estimated on the basis of the values for the relaxation times in the n-hexyl-4-isothiocyanato-phenyl phase.
Abstract: Dielectric relaxation investigations on the mesogen 1-n-hexyl-4-(4-isothiocyanato-phenyl)bicyclo[2,2,2]octane in the nematic and isotropic phases have been carried out in the frequency region from about 1 kHz to 1 GHz. Two relaxation processes have been observed in both the isotropic and nematic phases, when the measurements of the electric permittivity versus frequency are made parallel to the orientation axis of the liquid crystal. The possible mechanisms responsible for these two processes are discussed. The height of the potential barrier which hinders the rotation of the liquid crystal molecules around the short axis in the nematic state, and the order parameter of the liquid crystal under investigation have been estimated on the basis of the values for the relaxation times in the nematic and isotropic phases.
9 citations
TL;DR: In this paper, the debye functions have been used to describe the rotation of the permanent dipole moment around two main molecular axes in the liquid crystal 1-(4isothio-cyanatophenyl)-2-(4hexyl-bicyclo[2,2, 2] octane-1)ethane in the nematic and isotropic phases.
Abstract: Abstract Static and dynamic investigations of the dielectric properties of the liquid crystal 1-(4-isothio-cyanatophenyl)-2-(4-hexyl-bicyclo[2,2,2]octane-1)ethane in the nematic and isotropic phases have been carried out in the frequency region from 1 kHz to 1 GHz. Two relaxation processes, described by the Debye functions, have been observed not only in the isotropic but also in the nematic phase, when the measurements of the electric permittivity vs. frequency have been made parallel to the orientation axis of liquid crystal. These processes are related to the rotation of the permanent dipole moment around two main molecular axes. The height of the potential barrier which hinders the rotation of the liquid crystal molecule around the short axis in the ordered nematic phase and the order parameter of the liquid crystal investigated have been estimated on the basis of the relaxation time values in the nematic and isotropic phases.
5 citations
TL;DR: In this article, the guest order parameter as a function of temperature for five dichroic azo dyes dissolved in four members (pentyl to octyl) of the homologous series of n-alkyl-4-(4-isothiocyanatophenyl)bicyclo[2, 2,2]octanes has been evaluated.
Abstract: On the basis of the polarized absorption spectra, the guest order parameter as a function of temperature for five dichroic azo dyes dissolved in four members (pentyl to octyl) of the homologous series of n-alkyl-4-(4-isothiocyanatophenyl)bicyclo[2,2,2]octanes has been evaluated. Moreover, the influence of the dichroic dye addition on the nematic-isotropic phase transition temperature has been examined. The relation between the molecular geometry of the guest, its orientation efficiency in the nematic host and the clearing temperature of the azo dye-liquid crystal mixtures has been determined. The experimental results have been compared in some detail with calculations performed on the basis of the mean field theory for binary mixtures.
4 citations