A Fluid Liquid‐Crystal Material with Highly Polar Order |
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| Authors: | Hiroya Nishikawa Kazuya Shiroshita Hiroki Higuchi Yasushi Okumura Yasuhiro Haseba Shin‐ichi Yamamoto Koki Sago Hirotsugu Kikuchi |
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| Affiliation: | 1. Institute for Materials Chemistry and Engineering (IMCE), Kyushu University, Kasuga, Fukuoka, Japan;2. Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka, Japan;3. JNC Petrochemical Corporation, Ichihara, Chiba, Japan |
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| Abstract: | An anomalously large dielectric permittivity of ≈104 is found in the mesophase temperature range (MP phase) wherein high fluidity is observed for a liquid‐crystal compound having a 1,3‐dioxane unit in the mesogenic core (DIO). In this temperature range, no sharp X‐ray diffraction peak is observed at both small and wide Bragg angles, similar to that for a nematic phase; however, an inhomogeneous sandy texture or broken Schlieren one is observed via polarizing optical microscopy, unlike that for a conventional nematic phase. DIO exhibits polarization switching with a large polarization value, i.e., P = 4.4 µC cm?2, and a parallelogram‐shaped polarization–electric field hysteresis loop in the MP phase. The inhomogeneously aligned DIO in the absence of an electric field adopts a uniform orientation along an applied electric field when field‐induced polarization switching occurs. Furthermore, sufficiently larger second‐harmonic generation is observed for DIO in the MP phase. Second‐harmonic‐generation interferometry clearly shows that the sense of polarization is inverted when the +/? sign of the applied electric field in MP is reversed. These results suggest that a unidirectional, ferroelectric‐like parallel polar arrangement of the molecules is generated along the director in the MP phase. |
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| Keywords: | dielectric anisotropy ferroelectric‐like polarization highly polar order liquid crystals |
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