Title:	Parameters of LC molecules’ movement measured by dielectric spectroscopy in wide temperature range
Authors:	Chausov, D N Kurilova, A D Belyaev, V.V. Kumar, Sandeep
Keywords:	Dielectric relaxation Dielectric spectroscopy Crossover frequency Molecular friction Rotational diffusion Liquid crystals
Issue Date:	2-Mar-2018
Publisher:	Elsevier B. V.
Citation:	Opto-Electronics Review, 2018, Vol.26, p44-49
Abstract:	Dielectric properties of a nematic liquid crystal (NLC) mixture ZhK-1282 were investigated in the frequency range of 102–106Hz and a temperature range of −20 to 80 °С. On the basis of the Debye’s relaxation polarization model dielectric spectra of temperature dependence of the orientational relaxation time τ and the dielectric strength δe were numerically approximated at the parallel orientation of a molecular director relative to alternating electric field. Influence of ester components in the mixture plays crucial role in relaxation processes at low temperature and external field frequency. The activation energy of the relaxation process of a rotation of molecules around their short axis was measured in a temperature interval of −20 to  +15 °С in which the dispersion of a longitudinal component of the dielectric constant takes place. The energy of potential barrier for polar molecules rotation in the mesophase was calculated. The value of the transition entropy from the nematic to isotropic phase was obtained from this calculation. The values of the coefficient of molecular friction and rotational diffusion were obtained by different methods. The experimental data obtained are in a satisfactory agreement with the existing theoretical models.
Description:	Restricted Access.
URI:	http://hdl.handle.net/2289/6887
ISSN:	1230-3402
Alternative Location:	http://arxiv.org/abs/cond-mat/ https://doi.org/10.1016/j.opelre.2017.12.001
Copyright:	2018 Elsevier Inc.
Appears in Collections:	Research Papers (SCM)

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