Paper
6 October 2005 Electric birefringence of some nematic liquid crystals having hexyl tail
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Abstract
Electro-optical Kerr effect data have been obtained for 6CB, 6CHBT, 6PCH and 6BOBT at temperatures above the nematic-isotropic transition temperature. All the compounds had a positive Kerr constant which increased with decreasing of temperature. The second order phase transition temperatures, T*, were determined for these compounds. The linear dependence of (T - T*)-1 on the Kerr constant is found to be relatively in good agreement with the predications of the Landau-De Gennes model. The replacement of aromatic ring by a flexible cyclohexyl group and or by a bulkier bicyclooctane has a marked effect on the birefringence. Hexyl 4-(4-isothiocyanato-phenyl) bicycle [2,2,2] octane, 6BOBT, with the highest transition temperature had the lowest Kerr constant. In contrast, hexyl cyanobiphenyl,6CB, showed the largest Kerr constant (6BOBT → 6CHBT ≈ 6PCH → 6CB). The effect of the rigid core and polar head group of the liquid crystals was investigated.
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H. Khoshsima, H. Tajalli, A. Ghanadzadeh, and R. Dabrowski "Electric birefringence of some nematic liquid crystals having hexyl tail", Proc. SPIE 5947, Liquid Crystals: Optics and Applications, 59470P (6 October 2005); https://doi.org/10.1117/12.620884
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KEYWORDS
Liquid crystals

Birefringence

Temperature metrology

Kerr effect

Electro optics

Anisotropy

Dielectrics

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