| The threshold characteristics of an instability in the form of longitudinal flexo-electric domains, arising in thin layers of liquid crystals exposed to a d.c. field were investigated for two nematic mixtures based on azoxy-and ester compounds. The experimental dependences of the threshold voltage and the domain period as functions of dielectric anisotropy were obtained. It was shown that maximum distortion of a homogeneously oriented layer corresponds to the central region of the layer. The difference of the flexo-electric moduli e* = e 11 - e33 was calculated for the mixtures by comparing the experimental data with the theory for two-dimensional flexo-electric deformation developed by Bobylev and Pikin. |
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