| Popis: |
Long-range forces between ultra-fine particles imbedded in liquid crystal (LC) result in intriguing colloids. Embedded inorganic particles in LC contribute to the properties of the LC matrix. Large (>>mkm) colloidal particles form defects in LC matrices due to strong director deformations and ensembles of these particles and defects can form complex structures. Small particles at its high concentration (> 2-3% by weight) create almost a rigid LC suspension. We show that at low concentrations LC submicron colloids appear similar to a pure LC with no readily apparent evidence of dissolved particles, but possess unique properties. The diluted suspensions are stable, because the small concentration of submicron particles does not significantly perturb the director field in the LC, and interaction between the particles is weak. At the same time, the submicron particles share their intrinsic properties with the LC matrix due to the anchoring with the LC. We report on the development and unique properties of the diluted suspensions of ferroelectric submicron particles. Our results show that doping a nematic LC matrix with ferroelectric submicron particles results in a suspension, which possesses an enhanced dielectric anisotropy and reveals ferroelectric and paraelectric properties inherent to the submicron particles. In particular, we observed essential decrease of the driving voltage of the quadratic dielectric response and non-usual linear dipole response of the suspensions on the application of ac-field. We present a theoretical model of dielectric properties of ferroelectric suspensions. |
