Domain Formation and Molecular Alignment in Nematic Liquid Crystal Mixtures with Positive Dielectric Anisotropy

Abstract

The relative effectiveness of electric and magnetic fields for producing molecular alignment and consequent instabilities has been investigated in nematic liquid crystal mixtures of MBBA and MBCA with positive dielectric anisotropy in moderately thick samples. Domain formation and its stability has been related to the magnitudes of positive dielectric anisotropy. Grid patterns have been observed in mixtures with dielectric anisotropy between +0.5 and +1.2. The variation of threshold voltage with dielectric anisotropy for domain formation and dielectric alignment in moderately thick and thin samples has been reported. It is found that the maximum values of positive dielectric anisotropy below which electrohydrodynamic instability is likely to exist in thin and moderately thick samples differ.