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Synthesis, Characterization, Spontaneous Polarization and Dielectric Relaxation Studies in the Antiferroelectric and Ferroelectric Phases of an Achiral Banana Liquid Crystal: Bent-16 of an Achiral Banana Liquid Crystal: Bent-16 P.

Chalapathi , A V and Srinivasulu, M and Goud, B V S and Pisipati, V G K M and potukuchi, D M (2005) Synthesis, Characterization, Spontaneous Polarization and Dielectric Relaxation Studies in the Antiferroelectric and Ferroelectric Phases of an Achiral Banana Liquid Crystal: Bent-16 of an Achiral Banana Liquid Crystal: Bent-16 P. Ferroelectrics, 322 (1). pp. 53-67. ISSN 1563-5112

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Abstract

Synthesis and textural characterization along with spectroscopic (IR) confirmation (of supra molecular bond formation) are reported for an achiral Banana Liquid Crystal (BLC) Bent-16, viz., 1,3-phynylene bis(4-hexadecylbenzoate). Bent-16 exhibits a B2 phase which undergoes a paramorphotic change to B2(FE) phase with decreasing temperature. The intra-B2 i.e., AF to FE transition is confirmed through double peaked spontaneous polarization profiles. Results of calorimetry (Tc and �H from DSC) agree with polarization thermal microscopy (TM) and confirm first order nature of Isotropic to B2 phase transition. Low-frequency (5 Hz–12 MHz) dielectric measurements of capacitance C (T) and capacitance dC/dT agree with TM and DSC. Two orientational relaxations viz., a low-frequency (LF ∼ 1 KHz) and a high frequency (HF ∼ 1 MHz) corresponding to a slow and fast time regimes respectively are reported. Arrhenius shift of relaxation frequency fR in LF and HF regions infer comparable activation energy in Antiferroelectric phases with the estimated energies from other experiments in other BLCs. The temperatures trend of dielectric increment �ε and α-parameter estimated from off-centred Debye’s dispersion in both the B2 phases (LF and HF mechanism) support relative confinement of the dipole.

Item Type: Article
Uncontrolled Keywords: Achiral; Bent; liquid crystal; antiferroelectric; relaxation
Subjects: Engineering > MIT Manipal > Chemistry
Depositing User: MIT Library
Date Deposited: 09 Feb 2013 05:29
Last Modified: 09 Feb 2013 05:29
URI: http://eprints.manipal.edu/id/eprint/78307

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