Electro-optical features of antiferroelectric liquid crystal material (S)-(+)-4-(1-methylheptyloxycarbonyl) phenyl 4′-(6-octanoyloxyhex-1-oxy) biphenyl-4-carboxylate in its ferro and antiferroelectric phases

A detailed investigation of the electro-optical switching parameters of an antiferroelectric liquid crystal (S)-(+)-4-(1-methylheptyloxycarbonyl) phenyl 4′-(6-octanoyloxyhex-1-oxy) biphenyl-4-carboxylate (abbreviated as S-7H6Bi) has been carried out. S-7H6Bi has paraelectric (SmA⁎) and ferroelectric (SmC⁎) phases in addition to antiferroelectric (SmC⁎A) phase. Switching parameters viz. spontaneous polarization and switching time were determined by polarization reversal method. The spontaneous polarization (Ps) is found to be highly temperature dependent and decreases with temperature. The maximum value of Ps is found to be ∼90 nC/cm2 whereas the switching time (ts) is found to be of the order 1-2 ms. The temperature dependent torsional viscosity (γt) is of the order 10 Pa sec. It increases with decrease in temperature.