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Jpn. J. Appl. Phys. 45 (2006) pp. L1013-L1015  |Previous Article| |Next Article|  |Table of Contents|
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Letter

Characterization of Nematic Phase of Banana Liquid Crystal

Khoa Van Le, Surajit Dhara¹, Bukkinakere Kapanipathaiya Sadashiva², Yoichi Takanishi and Hideo Takezoe

Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan
¹School of Physics, University of Hyderabad, Hyderabad-500046, India
²Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore-560080, India

(Received July 1, 2006; accepted August 7, 2006; published online September 15, 2006)

We report the first detailed optical and electrical characterizations of the nematic (N) phase of a banana liquid crystal, i.e., pretilt angle, and optical and dielectric anisotropies, and point out the difference from those of rodlike molecules. The pretilt angle measurements using a conventional crystal rotation method show that the pretilt angle is very small (less than 1°) even in cells with a polyimide film yielding a high pretilt angle like 8° for calamitic molecules. We also measured the birefringence Δn in the N phase as a function of temperature and estimated the orientational order parameter S. The medium shows a small negative dielectric anisotropy in the N phase and the anisotropy becomes large in the B2 phase mainly because of the tilt of the molecules from the layer normal.

URL: http://jjap.jsap.jp/link?JJAP/45/L1013/
DOI: 10.1143/JJAP.45.L1013

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