Synthesis, characterization, spontaneous polarization and dielectric relaxation studies in the antiferroelectric and ferroelectric phases of an achiral banana liquid crystal: Bent-16

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 ofcalorimetry (T_c and ΔH from DSC) agree with polarization thermal microscopy (TM) and confirm first order nature of Isotropic to 82 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 f_R in LF and HF regions infer comparable activation energy in Antiferwelectric phases with the estimated energies from other experiments in other BLCs. The temperatures trend of dielectric increment δε 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.