Journal ArticleDOI
Phase transitions from the isotropic liquid to liquid crystalline mesophases studied by linear and nonlinear static dielectric permittivity
Reads0
Chats0
TLDR
Despite significant differences between N, Sm-A, and Sm-E phases the same pretransitional behavior of epsilon and NDE in the isotropic phase, described by critical exponents gamma = 1 and alpha = 0.5, was found.Abstract:
Results of studies of static dielectric permittivity (epsilon) and nonlinear dielectric effect (NDE) in the isotropic phase of 4-n-4'-isothiocyanatobiphenyl (nBT) homologous series from n = 2 to n = 10 exhibiting the isotropic-smectic E (I-SmE) transition, are presented. They are compared with results of similar studies in 4-cyano-4-n-alkylbiphenyls (nCB) from n = 4 to n = 12. In this homologous series isotropic-nematic (I-N) and isotropic-smectic-A (I-Sm-A) transitions take place. Despite significant differences between N, Sm-A, and Sm-E phases the same pretransitional behavior of epsilon and NDE in the isotropic phase, described by critical exponents gamma = 1 and alpha = 0.5, was found. It has been shown that when the length of the alkyl chain of a compound increases the discontinuity of the transition drops in nBT and rises in nCB. The influence of pressure on the discontinuity is also discussed.read more
Citations
More filters
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
On the pressure evolution of the melting temperature and the glass transition temperature
TL;DR: In this article, the evolution of the melting temperature and the glass temperature from negative pressures up to very high pressures is discussed, which is governed solely on pressure invariant coefficients πg,m, b and c. The analysis was carried out for sodium, (Ca, Al)(Al, Si)O3 magmatic mixture, liquid crystalline 5CB, germanium, magmatic melt albite, selenium and epoxy resin EPON 828.
Journal ArticleDOI
Infrared spectroscopic and X-ray studies of the 4-propyl-4'-isothiocyanatobiphenyl (3TCB).
M. Jasiurkowska,Jan Sciesiński,Joanna Czub,Maria Massalska-Arodź,Robert Pełka,E. Juszyńska,Yasuhisa Yamamura,Kazuya Saito +7 more
TL;DR: The results of mid-infrared spectroscopy and X-ray studies of the third member of the 4-n-alkyl-4'-isothiocyanatobiphenyl (nTCB) homologous series are presented and arguments supporting the identification of the glass of smectic E phase are given.
Journal ArticleDOI
Distortion-sensitive insight into the pretransitional behavior of 4-n-octyloxy-4′-cyanobiphenyl (8OCB)
Sylwester J. Rzoska,Aleksandra Drozd-Rzoska,Prabir K. Mukherjee,David López,David López,Julio Cesar Martinez-Garcia +5 more
TL;DR: Results of studies of the static and dynamic dielectric properties in rod-like 4-n-octyloxy-4'-cyanobiphenyl with isotropic (I)-nematic (N)-smectic A (SmA)-crystal (Cr) mesomorphism, combined with measurements of the low-frequency nonlinear dielectrics effect and heat capacity are presented.
Journal ArticleDOI
Study of polymorphism of 4-hexyl-4'-isothiocyanatobiphenyl by complementary methods.
TL;DR: Calorimetric measurements indicate the existence of two stable crystalline phases of 4-hexyl-4'-isothiocyanatobiphenyl and the structural information about the glass of the smectic E obtained from the diffraction studies is complemented by textures recorded by polarized microscopy.
References
More filters
Journal ArticleDOI
Eine einfache molekular-statistische Theorie der nematischen kristallinflüssigen Phase. Teil II
Wilhelm Maier,Alfred Saupe +1 more
TL;DR: In this paper, the authors describe a mittlere Innere Feld einer nematischen Molekülanordnung abgeleitet, and gezeigt, daß this Innere Field in einem gewissen Temperaturbereich einen nematicalhen Ordnungszustand bewirken muß and daß dieser ordnung sustand was with einer bestimmten Temperatur diskontinuierlich und unter Energieaufnahme in die isot
Journal ArticleDOI
Short Range Order Effects in the Isotropic Phase of Nematics and Cholesterics
TL;DR: In this article, the authors assume that the local state of order in the isotropic phase is a symmetric traceless tensor Qαβ, proportional to the anisotropic part of a tensor property such as the magnetic susceptibility.
Journal ArticleDOI
Phenomenology of short-range-order effects in the isotropic phase of nematic materials
TL;DR: In this article, the magnetic birefringence, the intensity and the width in frequency of the Rayleigh scattering, and the flow bireringence are discussed in terms of a small number of phenomenological parameters.
Journal ArticleDOI
Landau theory of the nematic-isotropic phase transition
TL;DR: A review of the wide variety of predictions that results from a Landau-type of description of the nematic-isotropic phase transition is given in this paper, which includes a discussion of the nature of the order parameter and of the various types of possible phases.
Journal ArticleDOI
Pretransitional Phenomena in the Isotropic Phase of a Nematic Liquid Crystal
T. W. Stinson,J. D. Litster +1 more
TL;DR: In this article, the authors have observed a divergence of the magnetic birefringence, and a critical increase and slowing of the fluctuations in order in the isotropic phase of a nematic liquid crystal.