Dielectric spectroscopy and electrical conductivity measurements of a series of orthoconic antiferroelectric liquid crystalline esters

Abstract

Dielectric spectroscopic measurements of five homologous series of orthoconic antiferroelectric liquid crystalline (OAFLC) esters (S)-MHPOBC ((S)-4-(1-methylheptyloxy) carbonyl phenyl 4^’-octyloxy-4-biphenylcarboxylate) has been investigated. The investigated compound contains SmC*, SmC_A* and SmA phase with SmC_A* phase at a broad temperature range. Parameters such as absorption curve, dispersion curve, Cole-Cole plot, relaxation frequency, relaxation time, dielectric strength and electrical conductivity has been discussed. The structure property correlations of these compounds are also highlighted in the light of the dielectric measurements. Compound S1.6 (FF) and S2.6 (FH) has dielectric strength of around 250 in the SmC* phase due to the presence of Goldstone mode.

Keywords:

• Dielectric spectroscopy
• orthoconic antiferroelectric liquid crystals
• Cole-Cole
• dielectric strength
• relaxation modes

Additional information

Funding

Department of Science and Technology, New Delhi is acknowledged for providing the financial support under grant EMR/2016/005001 and EEQ/2017/000829. S. Nepal is grateful to the Department of Science and Technology, New Delhi for the award of a Junior Research Fellowship.