Effects of dielectric and conductivity anisotropies on molecular alignment in a liquid crystal

The relative effectiveness of electric and magnetic fields for producing molecular alignment in a nematic liquid crystal has been investigated while changing the magnitudes of the dielectric and conductivity anisotropies. The comparison was made for an ordering of the molecules such that the average angle that a molecule makes with the magnetic field is 45^∘{}. The dielectric anisotropy was changed from ε_∥^'-ε_⊥^'=-0.2-1.0. A relationship involving dielectric, conductivity, and magnetic permeability anisotropies was found to be satisfied in a range of magnetic field strengths of 3-6 kG. If the torque due to the conductivity anisotropy was greater than the torque due to the dielectric anisotropy, stable Williams domains were likely to be observed, but if it was less, stable Williams domains were unlikely to occur. This has been shown earlier for materials exhibiting a negative dielectric anisotropy but this work emphasizes materials with a positive dielectric anisotropy.