Induction of smectic C phase in binary mixtures of compounds with cyano end groups

Abstract

We have studied binary mixtures of 4-cyanophenyl-3'-methyl-4'(4"-n-dodecylbenzoyloxy)benzoate (12 CPMBB) and 4-n-dodecylphenyl-3'-methyl-4'(4"-cyanobenzoy1oxy)benzoate (12 PMCBB). The former compound exhibits nematic, smectic A and reentrant nematic phases and the latter one nematic and smectic A phases with a possible A_dA₂, transition. Over a fairly wide composition range, the mixtures exhibit an induced smectic C phase on cooling the sample from the A phase. The phase diagram, and the temperature variations of the layer spacings for some specific compositions are reported. The possible origin of the C phase is also discussed.