Effect of Barium Titanate Particles on Dielectric and Electro-Optical Properties of a Smectic-a Liquid Crystal

Resumo

The effect of submicron ferroelectric BaTiO₃ particles on the dielectric and electro-optical properties of the smectic-A liquid crystal (LC) with a high negative dielectric anisotropy is investigated. It is shown that the addition of BaTiO₃ particles with a weight amount of 1% reduces insignificantly the transverse dielectric permittivity component ε_⊥ of, but significantly increases the longitudinal dielectric permittivity component ε_// of the smectic-A LC. As a result, the anisotropy of the dielectric permittivity Δε = ε_// − ε_⊥ of the smectic-A LC decreases. The addition of BaTiO₃ particles shifts the dispersion ε_⊥ toward lower frequencies. Both components of the electrical conductivity of LC colloid + BaTiO₃ are an order of magnitude higher than of the pure LC. The threshold voltage of the homeotropic-planar transition of the colloid is twice smaller, and its velocity is 6 times higher in comparison with the pure LC. A simple model explaining qualitatively all results obtained is presented.