Induced smectic phases in binary mixtures of a compound having a weakly polar end group and a compound having a non-polar end group

Abstract

We have studied the phase diagram of binary mixtures of 4'-n-heptyl-4-bromobiphenyl (a non-mesomorphic compound having a weakly polar terminal group) and 4,4'-di-n-heptyloxyazoxybenzene (a mesomorphic compound having a non-polar terminal group). The mixture exhibits an induced smectic A phase over a wide composition range and also an induced smectic E phase over a narrow composition range. X-ray studies show that the molecular arrangement in the smectic A phase is monolayer for all compositions. We have also observed defects of strength ±pL2 and ±pL3/2 in the nematic phase in a certain composition range of the mixture.