NOVEL MEASUREMENT METHOD FOR FLEXOELECTRIC COEFFICIENTS OF NEMATIC LIQUID-CRYSTALS

A new measurement method for the flexoelectric coefficient e(11) and e (33) (corresponding to the splay and bend strain, respectively) of nem atic liquid crystals (LCs) is proposed. The values of e(11) + e(33) an d e(11) - e(33) can be determined by fitting experimental electrooptic al characteristics of hybrid aligned nematic (HAN) cells with numerica l simulations. For the measurement of e(11) + e(33) and e(11) - e(33), a dc electric field is applied along the cell normal and along the ce ll surface, respectively. The measurements were carried out for two ne matics, N-(4-methoxybenzylidene)-4'-n-butylaniline (MBBA) and ZLI-4792 . As a result, e(11) + e(33) = (-5.4 = 1.0) x 10(-11) C/m and e(11) - e(33) = (1.4 = 0.1) x 10(-11) C/m for MBBA, \e(11) + e(33)\ less than or equal to 1.0 x 10(-11) C/m and e(11) - e(33) = (-1.5 +/- 0.1) x 10( -11) C/m for ZLI-4792 were obtained.