Dielectric and switching properties of a highly tilted AFLC material (S)-(+)-4-(1-methylheptyloxycarbonyl)-2,3-difluorophenyl 4′-[3-(2,2,3,3,4,4,4-heptafluorobutoxy)prop-1-oxy]biphenyl-4-carboxylate |
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Authors: | Avneesh Mishra Roman S. Dabrowski |
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Affiliation: | 1. Soft Materials Research Laboratory, Centre of Material Sciences, Institute of Interdisciplinary Studies, University of Allahabad, Allahabad, India;2. Institute of Chemistry, Military University of Technology, Warsaw, Poland |
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Abstract: | Thermodynamic, dielectric, optical and switching parameters of a single-phase antiferroelectric (AF) liquid crystalline material (S)-(+)-4-(1-methylheptyloxycarbonyl)-2,3-difluorophenyl 4′-[3-(2,2,3,3,4,4,4-heptafluorobutoxy)prop-1-oxy]biphenyl-4-carboxylate have been studied. These studies show wide temperature range (~97.8°C–25.3°C) of AF SmC*A phase in the material. The dielectric studies have been carried out in the frequency range of 1 Hz–35 MHz under planar anchoring conditions of the molecules. The dielectric spectrum of the SmC*A phase exhibits three relaxation modes due to the collective as well as individual molecular processes. Relaxation frequencies of these modes lie in the range of kHz–MHz regions. Relative permittivity of the material (at 10 kHz) varies from ~8.8 at 98.8°C to 9.9 at 41.0°C. Maximum tilt of the molecule in the SmC*A phase is ~43°C. Spontaneous polarisation, switching time and rotational viscosity have also been determined. The maximum value of PS is ~439 nC/cm2 and switching time is the order of 1–5 millisecond, whereas viscosity is moderate. |
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Keywords: | antiferroelectric liquid crystal antiferroelectric Goldstone mode dielectric permittivity relaxation frequency spontaneous polarisation switching time |
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