Measurement of Elastic Constant and Intrinsic Twist of Ferroelectric SmC* Liquid Crystal

The elastic constant B 3 and the intrinsic twist D of a ferroelectric SmC* liquid crystal and their temperature dependences were measured by making use of the selective reflection in a homeotropically aligned cell, and the critical electric field E c needed to unwind the helix was also estimated. E c was much smaller than a critical electric field when the dechiralization lines disappear in a homogeneously aligned cell. The constants determined here are considered not to be influenced by the wall anchoring of the glass plate. When we apply a simple power law, α(1-T/T c)γ, to the temperature dependences of B 3, D and E c, the exponents γ will be 0.44, 0.81 and 0.95, respectively, where T c is the SmC*-SmA transition point.