Journal ArticleDOI
Optical and x-ray evidence of the "de Vries" Sm-A*-Sm-C* transition in a non-layer-shrinkage ferroelectric liquid crystal with very weak interlayer tilt correlation.
TLDR
A non-layer-shrinkage fluorinated ferroelectric liquid crystal compound, 8422[2F3], has been characterized by means of optical, x-ray, and calorimetric methods and there is strong evidence that the second-order Sm-A*-Sm-C* transition is well described by the diffuse cone model of de Vries.Abstract:
A non-layer-shrinkage fluorinated ferroelectric liquid crystal compound, 8422[2F3], has been characterized by means of optical, x-ray, and calorimetric methods. The orientational distribution within macroscopic volumes, determined through wide-angle x-ray scattering and birefringence measurements, was found to be identical in the $\mathrm{Sm}\ensuremath{-}{A}^{*}$ and helical $\mathrm{Sm}\ensuremath{-}{C}^{*}$ phases. Together with the absence of layer shrinkage, this constitutes strong evidence that the second-order $\mathrm{Sm}\ensuremath{-}{A}^{*}--\mathrm{Sm}\ensuremath{-}{C}^{*}$ transition in this material is well described by the diffuse cone model of de Vries. The absolute values of the layer spacing show that the molecules aggregate to antiparallel pairs. The molecular interaction across the layer boundaries will then occur only between fluorine atoms, leading to unusually weak interlayer tilt direction correlation. This explains the experimental observations of a very easily disturbed $\mathrm{Sm}\ensuremath{-}{C}^{*}$ helix and a peculiar surface-stabilized texture. Tilt angle and birefringence values as a function of field and temperature have been evaluated in the $\mathrm{Sm}\ensuremath{-}{A}^{*}$ and $\mathrm{Sm}\ensuremath{-}{C}^{*}$ phases and the results corroborate the conclusions from the x-ray investigations.read more
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Journal ArticleDOI
Chiral 5-phenylpyrimidine liquid crystals with ‘de Vries-like’ properties: dependence of electroclinic effect and ferroelectric properties on carbosilane nanosegregation
TL;DR: In this paper, a series of tri-, di-and monocarbosilane mesogens with a 5-phenylpyrimidine core and a chiral (S,S)-2,3-difluorohexyloxy chain were synthesized and characterized.
Journal ArticleDOI
Observation of exceptional ‘de Vries-like’ properties in a conventional aroylhydrazone based liquid crystal
Hemant Kumar Singh,Sachin Kumar Singh,Rajib Nandi,D. S. Shankar Rao,S. Krishna Prasad,Ranjan K. Singh,Bachcha Singh +6 more
TL;DR: In this article, a straight alkoxy chain-terminated conventional aroylhydrazone based liquid crystal N-(4-(tetradecyloxy)-2-hydroxybenzylidene)-4′((4′(hexadecycloxy)benzinyl)oxy) benzohydrazide (BSac-1416) undergoes the SmA-SmC phase transition with a maximum layer contraction of 0.65%.
Journal ArticleDOI
Germanium liquid crystals
William N. Thurmes,K. M. More,Michael R. Meadows,Matthew B. O'Neill,Rohini T. Vohra,Michael D. Wand +5 more
TL;DR: In this paper, germanium-containing liquid crystals were incorporated into smectic C mixtures, and they showed small cone angles which fall smoothly and extrapolate to zero.
Journal ArticleDOI
Phase Transitions and Characterization in a Chiral Smectic-AdeVries Liquid Crystal by Low-Frequency Dielectric Spectroscopy
TL;DR: In this paper, a low-frequency (10-Hz-6.5MHz) dielectric analysis was carried out in the Smectic-AdeVr phase exhibited by a chiral Liquid Crystal molecule viz., TSiKN65F.