The optical transmittance and the electrical capacitance as a function of the externally applied dc voltage are obtained for a twisted nematic cell composed of inorganic clay; i.e., sodium montmorillonite, as an additive to the organic liquid crystal ET Higher loaded nematic, with smectite clay content of over 3 wt%, exhibits wider voltage-transmittance and voltage-capacitance hystereses, indicating that such cells suffer from more serious ion-charge effects and the orientation barrier of the liquid crystal. Experimental evidence suggests that the addition of merely 0.5-1% by weight of clay substantially rectifies the electro-optical characteristics of the pristine nematic, leading to an apparent lowering of the dc threshold voltage.
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