Charge accumulation in vicinity of escaped disclinations

The escaped disclinations arising in capillary tubes or in Schlieren texture, were analyzed numerically. The flexoelectric properties of the nematic liquid crystal and the presence of the ionic space charge were taken into account. The splay and bend deformations, occurring in these systems, led to the flexoelectric polarization which in turn gave rise to the potential differences and charge redistribution in the samples. The director orientation angle, the electric field strength and the space charge density were calculated as functions of radial coordinate by solving the torques equation and Poisson equation. For example, in the capillary with homeotropic boundary conditions, the effective positive space charge occupied the relatively large central regions, whereas the negative space charge gathered at the wall. In the Schlieren textures, the positive space charge was accumulated on the disclination lines and in their close neighborhood. The negative charge was removed from this region and spread over the rest of the layer. In the highly pure nematics, the radial electric field of order 10⁴ V/m arose in central parts of the capillaries and in vicinity of the disclinations in the Schlieren texture. The concentration of ions accumulated on the disclination lines in the Schlieren texture of well purified nematic exceeded the average bulk concentration of ionic impurities by nearly two orders of magnitude.