Possible Influence of Layer Deformation and Chiral Segregation on Dielectric Modes in the Dark Conglomerate Liquid Crystal

Dielectric spectroscopy is used to investigate the structure, molecular dynamics, and relaxation phenomena in electric-field-induced switchable dark conglomerate (DC) phases in a bent-core liquid crystal. The DC phases are obtained by applying a high-frequency ac electric field in the B1rev phase or by cooling under a dc or an ac field from the isotropic phase. Although the DC phases exhibit good electro-optic switching properties, the dielectric parameters are different from those observed in typical lamellar SmCP phases and similar to those obtained in a non-switchable DC phase. We therefore propose that the dielectric response and reduced intensity of the relaxation modes may be a general feature in DC phases and may owe its origin to the deformed layer structure in which certain molecular motions are impeded. Further, we find that in the field-induced DC phases derived from the isotropic phase, the dielectric modes are affected by chiral segregation promoted by the applied field.