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Full-Text Articles in Physics

Odd-Even Effects In Bent-Core Compounds Containing Terminal N-Alkyl Carboxylate Groups, S. Umadevi, Antal Jakli, B. Sadashiva Oct 2006

Odd-Even Effects In Bent-Core Compounds Containing Terminal N-Alkyl Carboxylate Groups, S. Umadevi, Antal Jakli, B. Sadashiva

Antal Jakli

A homologous series of eleven five-ring symmetrical bent-core compounds containing terminal n-alkyl carboxylate groups were synthesized, characterized and their dielectric and electro-optical properties have been investigated. The lower homologues (n = 6-11) of the series show B-2 structures with an interesting odd-even effect concerning their local director tilt and polar arrangements. This odd-even effect probably is due to steric (entropic) reasons, which are not suppressed by the relatively low polar interaction. Three of the middle homologues display a B-7' phase, which is bistable and shows linear electro-optical switching with a transition to the chiral antiferroelectric smectic phase at a lower …


Electrically Tunable Lens Based On A Dual-Frequency Nematic Liquid Crystal, Oleg Pishnyak, Susumu Sato, Oleg Lavrentovich Jul 2006

Electrically Tunable Lens Based On A Dual-Frequency Nematic Liquid Crystal, Oleg Pishnyak, Susumu Sato, Oleg Lavrentovich

Oleg Lavrentovich

We report on an electrically controlled liquid-crystal-based variable optical lens filled with a dual-frequency nematic material. The lens design employs a hole-patterned electrode structure in a flat nematic cell. In order to decrease the lens switching time we maximize the dielectric torque by using a dual-frequency nematic material that is aligned at an angle approximately 45 degrees with respect to the bounding plates by obliquely deposited SiOx, and by using an overdrive scheme of electrical switching. Depending on the frequency of the applied field, the director realigns either toward the homeotropic state (perpendicular to the substrates) or toward the planar …


Fluorine Containing Nonsymmetrical Five-Ring Achiral Banana-Shaped Compounds With Columnar And Synclinic Antiferroelectric Layered Phases, Channabasaveshwar Yelamaggad, Indudhara Shashikala, Uma Hiremath, Guangxun Liao, Antal Jakli, Doddamane Shankar Rao, Subbarao Prasada, Quan Li Jun 2006

Fluorine Containing Nonsymmetrical Five-Ring Achiral Banana-Shaped Compounds With Columnar And Synclinic Antiferroelectric Layered Phases, Channabasaveshwar Yelamaggad, Indudhara Shashikala, Uma Hiremath, Guangxun Liao, Antal Jakli, Doddamane Shankar Rao, Subbarao Prasada, Quan Li

Antal Jakli

The phase transitional behavior of two homologous series of five-ring banana-shaped compounds comprising fluorine substituents synthesized through covalent linking of two chemically dissimilar rod-like anisometric cores (arms) to central 1,3-phenylene is reported. The novelty of these molecules originates from the fact that the molecules are highly nonsymmetrical. One of the arms, which is either salicylaldimine or Schiff base core, possesses two vicinal fluorine atoms at the terminal ring having a n-decyloxy tail; while the n-alkyl tail attached to the other arm was varied to realize a homologous series of compounds. The mesophases have been characterized by several complementary studies. The …