Journal ArticleDOI
Linear and nonlinear dielectric studies in the isotropic and smectic E phases in 4,4-alkyl-4´-isothiocyanatobiphenyl
S. Hensel-Bielowka,Sylwester J. Rzoska,Aleksandra Drozd-Rzoska,W Burian,M Czachor,Jerzy Zioło,Krzysztof Czupryński +6 more
TLDR
In this article, the Vogel-Fulcher law describes temperature and pressure dependences of the relaxation time in the isotropic, smectic E phase in 4,4-alkyl-4´-isothicyanatobiphenyls (4BT).Abstract:
Results are presented of studies of linear and nonlinear dielectric measurements in the isotropic, smectic E phase in 4,4-alkyl-4´-isothicyanatobiphenyls (4BT). The mean-field behaviour was valid up to the smectic E phase transition. In the smectic E phase the Vogel-Fulcher law describes temperature and pressure dependences of the relaxation time. An analysis of the higher temperature relaxation time data led to predictions of the mode coupling theory with the power law universal function = A (T - TC ) , where = -3.3, TC = 288 ± 15 K. Increase of pressure brings the ´´ curve closer to the Debye shape.read more
Citations
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Journal ArticleDOI
Dielectric studies of the 4-n-alkyl-4'-thiocyanatobiphenyl (nBT) homologous series (n=2-10) in the isotropic and E phases
Stanisław Urban,Krzysztof Czupryński,Roman Dąbrowski,Bo Gestblom,Joanna Janik,Horst Kresse,H. Schmalfuss +6 more
TL;DR: In this paper, the dielectric properties of nine members of the nBT (4n-alkyl-4thiocyanatobiphenyl, n= 2-10) homologous series in the crystal E (E) and isotropic (I) phases are presented.
Journal ArticleDOI
Subdiffusive dynamics of a liquid crystal in the isotropic phase
TL;DR: The isotropic phase dynamics of a system of 4-n-hexyl-4'-cyano-biphenyl (6CB) molecules has been studied by molecular dynamics computer simulations and it is shown that ODOF freezes earlier than TDOF, due to the strongly anisotropic environment that surrounds a 6CB molecule, even in the isotropics phase.
Journal ArticleDOI
X-ray diffraction, DFT theoretical, and IR polarized spectroscopic studies of the crystal-like E-mesophase of 4′-hexyloxy-isothiocyanatotolane (6OTOLT)
Paulina Majewska,Maria Rospenk,Bogusława Czarnik-Matusewicz,Andrzej Kochel,Lucjan Sobczyk,Roman Dąbrowski +5 more
TL;DR: In this paper, the dynamics of 6OTOLT molecules were analyzed based on IR absorption spectra and DFT calculations, and it was shown that an increase in the frequency of NCS vibrations can be expected in good agreement with experimental data.
Journal ArticleDOI
Direct transition from isotropic to smectic-E phase
TL;DR: In this article, the authors apply the Landau theory of phase transitions to the case of a direct isotropic to smectic-E transition and show that the coupling of the order parameters has crucial influence on the phase behavior and the order of the transition.
Journal ArticleDOI
Glassy dynamics in the isotropic phase of a smectogenic liquid crystalline compound.
TL;DR: Based on the enthalpy space and distortion-sensitive analysis, the prevalence of the mode coupling theory (MCT) "critical" and "glassy" dynamics is shown and it is shown that the value of the fragile strength coefficient D(T) is characteristic of a very fragile glassy liquid whereas the steepness index m is typical of a strong one.
References
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Journal ArticleDOI
Nonexponential relaxations in strong and fragile glass formers
TL;DR: In this article, a broad correlation of non-debye behavior with non-Arrhenius relaxations was found for different types of glass formers, distinguished by their respective molecular complexity.
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Analytical thermal lens instrumentation
Mladen Franko,Chieu D. Tran +1 more
TL;DR: In this article, a review describes recent instrumentation developments of the thermal lens techniques, focusing, modulation, sample position, sample cells, data acquisition, noise reduction, and applications of acousto-optic tunable filters.
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Critical behavior of dielectric permittivity in the isotropic phase of nematogens
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Nonlinear dielectric study of pretransitional effects in liquids above the phase transition temperature
Jerzy Małecki,Jerzy Zioło +1 more
TL;DR: In this paper, the authors measured dielectric permittivity in an electric field (NDE) measured for two solutions in the single-phase precritical region and for the isotropic phase of MBBA above the clearing temperature T c.
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The puzzle of the nematic-isotropic phase transition
TL;DR: In this article, the authors present experimental and theoretical results for the critical behavior in the isotropic phase of nematogens and discuss the possibility of tricritical behavior at the nematic-isotropic transition.