Domain Formation in Homogeneous Nematic Liquid Crystals

  • J. M. Pollack
  • J. B. Flannery


A new electrohydrodynamic mode in nematic liquid crystals (NLCs) was reported recently by Vistin1, and Greubel and Wolff.2 The boundary value problem describing the effect was solved by Penz and Ford3, based on the conduction-induced alignment mechanism of Helfrich.4 Known as the variable grating mode (VGM), this dc effect in planar electroded cells of NLCs with negative dielectric anisotropy is characterized as follows: In thin cells (<10µm) containing high resistivity (>1010Ωcm) material, parallel domains which resemble the well-known Williams striations5 are observed in the plane of the sample. The onset of domain structure occurs at a characteristic threshold voltage of 5–10 V, regardless of cell thickness L, but the linear domain density or spatial frequency, ν, is inversely proportional to L near threshold. The domains consist of regions of vortex-type fluid motion, and are visible by virtue of the spatially periodic variation of the anisotropic refractive index of the NLC and its director. These domains act as a volume phase grating whose relative phase factor φ = πLν/2 varies linearly with voltage above threshold.3


Liquid Crystal Nematic Liquid Crystal Diffraction Efficiency Domain Formation Cell Thickness 
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Copyright information

© Plenum Press, New York 1974

Authors and Affiliations

  • J. M. Pollack
    • 1
  • J. B. Flannery
    • 1
  1. 1.Rochester Corporate Research CenterXerox CorporationRochesterUSA

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