scholarly journals Electro-Optical and Photo Stabilization Study of Nematic Ternary Mixture

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2283
Author(s):  
Aleksandra Kalbarczyk ◽  
Noureddine Bennis ◽  
Jakub Herman ◽  
Leszek R. Jaroszewicz ◽  
Przemysław Kula

Liquid crystal materials composed of mixed nematic compounds find broad use in liquid crystal displays and photonic applications. A ternary mixture formed from three different nematic compounds shows peculiar behavior such as tunable electro-optical properties dependent on the frequency of the driving voltage. The paper presents an analysis of the response time and phase retardation of a frequency tunable nematic liquid crystal mixture (under code name 5005). This material possesses high birefringence (Δn = 0.32 at 633 nm) as well as high dielectric anisotropy (Δε = 6.3 at 100 Hz). The unique property of the 5005 mixture is frequency-controlled phase modulation, as in a dual frequency liquid crystal, while dielectric anisotropy goes to zero instead of being negative at high frequencies. For each component of the mixture, details on mesomorphic properties and their role in the formulation of the mixture are reported. The 5005 mixture was characterized by multiple investigation techniques, such as temperature dependence dielectric anisotropy, transmittance measurements image polarizing microscopy, and UV stability.

2009 ◽  
Vol 40 (1) ◽  
pp. 992
Author(s):  
Sebastian Gauza ◽  
Meizi Jiao ◽  
Shin-Tson Wu ◽  
Przemysław Kula ◽  
Roman Dabrowski ◽  
...  

2008 ◽  
Vol 16 (4) ◽  
Author(s):  
P. Kula ◽  
A. Spadło ◽  
J. Dziaduszek ◽  
M. Filipowicz ◽  
R. Dąbrowski ◽  
...  

AbstractCompounds with moderate and large negative dielectric anisotropy (Δɛ) are very attractive liquid crystal (LC) for vertical alignment mode (VA). Materials with such properties can be achieved by lateral substitution of a polar group into a mesogenic molecule. We synthesized some new LC materials with a negative value of Δɛ, a moderately high birefringence (Δn), and a low viscosity. The mesomorphic and physical behaviour of the novel biphenyls, terphenyls and quaterphenyls fluorosubstituted in the rigid core and also with fluorinated alkyl and alkoxy chains are investigated. The prepared series of four LC compounds are promising for new LC mixtures for various applications. Examples of nematic mixtures with Δɛ∼−3.25 will be presented.


Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 307 ◽  
Author(s):  
Trong Nghia Lang ◽  
Van Bao Bui ◽  
Yo Inoue ◽  
Hiroshi Moritake

Liquid crystals, which have high dielectric anisotropy even in the terahertz region and are easily controllable for dielectric permittivity by applying an electric field, have become increasingly attractive in recent years. The non-radiative dielectric (NRD) waveguide has a structure in which a dielectric line is sandwiched between two metal plates and by replacing the dielectric part with liquid crystal, a low loss liquid crystal-loaded NRD waveguide type terahertz phase shifter can be obtained. However, since the thickness of the liquid crystal layer is several hundred micrometers, it has a response time of as long as several hundred seconds when the driving voltage is removed. It is necessary to devise improvements for practical application. By inserting two polyethylene terephthalate (PET) films and reducing the thickness of the liquid crystal layer, the decay time was improved well, but the phase change was significantly reduced. In this study, we report improving both decay time and phase change with aligned nanofiber/liquid crystal complex. In addition, we demonstrate liquid crystal-load phase shifter, which has 360° phase change and the response time below one second.


1992 ◽  
Vol 277 ◽  
Author(s):  
Tomohisa Gotoh ◽  
Hideya Murai ◽  
Etsuo Hasegawa ◽  
Katsuhiro Mizoguchi

ABSTRACTTwo new types of reverse-mode polymer-dispersed liquid crystal films have been developed and successfully produced. The first was produced by UV-curing of a mixture of dual frequency addressable liquid crystal (DFALC) and UV-curable polymers under an applied voltage at a frequency lower than the crossover frequency (fc) of the DFALC. This first type is referred to as a dual frequency type. The second type was produced by injecting a liquid crystal having negative dielectric anisotropy into a specially prepared porous polymer film from which liquid crystal having positive dielectric anisotropy had previously been extracted. The type thus produced through such “negative-for-positive” substitution is referred to as a substitution type. While the dual frequency type can not be driven at a low frequency, substitution type can, which gives it a distinct advantage. Other electro-optic characteristics of the two types of films, including alignment properties of the liquid crystal molecules, are also discussed.


1999 ◽  
Vol 85 (11) ◽  
pp. 7511-7516 ◽  
Author(s):  
Takeshi Yamaguchi ◽  
Hajime Yamaguchi ◽  
Yasushi Kawata

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