Tilt angles and spontaneous polarization in induced S*cphases

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Abstract
Induced S*c phases can be obtained by doping several non-chiral Sc-host phases (H) with chiral polar compounds (G). The tilt angle θ of such systems and their spontaneous polarization P s were measured as a function of the mole fraction, x G, of the optically active compounds. In the S*c phase of a pure compound P s and θ are expected to be closely related to each other. Consequently, a material constant P 0 can be defined as P s = P 0 sin θ. In induced S*c-phases P s depends on the concentration of the optically active guest compound. In several cases P s(x G) deviates considerably from linearity. To investigate the origin of this non-linearity we measured θ and P s as function of x G. The question arises if P 0 depends on x G and/or on the molecular structure of G and H: P s(x G) = P 0(x G) sin θ (x G). Comparing the results of P 0(x G) for mixed systems with the same optically active dopant G we can make the following statements. As a result we can define a material constant, the polarization power ∂p: which is an inherent material constant for a given polar chiral dopant.