Selective reflection of light in binary mixtures with different types of smectic A phase

摘要

In the mixtures of chiral compounds in which smectic A phase exists in limited range of concemtration the selective reflection of light for compositions without smectic A phase can be from red to blue the same as above smectic phase or from blue to red as in mixtures without smectic phase. To check either the type of smectic A phase or the phenomenon of phase induction are responsible for the difference in the light colour sequence polar compounds having chiral nematic phase were mixed with compounds having nonpolar ('classic') smectic A phase or polar A_1 or A_d smectic phases in lower temperatures than chiral nematic phase (in these systems the smectic phase was destabilised) or with compounds having nematic phase chosen in such a way that smectic A_1 or A_d were induced in the system. It was found that the light colour sequence depends on the distance of compositions giving the selective reflection of the light in temperature-concentration scale from smectic phase.