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Observations of flexo-dielectric walls in a bent-core- calamitic nematic liquid crystal♣

H. P. HINOV1,* , Y. G. MARINOV1, A. G. PETROV1, UMA S. HIREMATH2, C. V. YELAMAGGAD2

Affiliation

  1. Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria
  2. Centre for Liquid Crystal Research, Jalahalli, Bangalore 560 013 India

Abstract

Experimental observations on the electrooptic behaviour of the bent-core-calamitic 4-((3-(4-(4- (decyloxy)benzoyloxy)benzoyloxy)phenylimino)methyl)-3-hydroxyphenyl 4-(6-(4'-cyanobiphenyl-4-yloxy) hexyloxy) benzoate in the nematic phase with a positive dielectric anisotropy were performed for the first time. The efforts were concentrated mainly on the flexoelectric behaviour of the nematic for the case of a d.c. or very low-frequency (up to 0.05 Hz) voltage applied across a highly tilted or homeotropic nematic layer with a thickness of 15 μm. Various flexo-dielectric domains, such as cross-like domains, π-walls, longitudinal flexo-dielectric walls, etc. were observed for voltages below 8 V. The cross-like domains were observed in initially homeotropic nematic regions. The π-walls were observed in highly tilted nematic regions. The cross-like domains and the π-walls can be erased at the threshold by applying an additional high-frequency (5 kHz) voltage of 1-2 Vrms. Our interpretation is that all these flexoelectric domains arise from the inhomogeneity of the electric field created by injection of ions from one of the electrodes..

Keywords

Bent Core-Calamitic Nematic, Flexoelectricity, Domains.

Submitted at: Nov. 5, 2008
Accepted at: Sept. 9, 2009

Citation

H. P. HINOV, Y. G. MARINOV, A. G. PETROV, UMA S. HIREMATH, C. V. YELAMAGGAD, Observations of flexo-dielectric walls in a bent-core- calamitic nematic liquid crystal♣, Journal of Optoelectronics and Advanced Materials Vol. 11, Iss. 9, pp. 1194-1197 (2009)