ON SOME ELASTIC INSTABILITIES IN BIAXIAL NEMATICS

Within the framework of the continuum elastic theory of biaxial nemati c liquid crystals, we have addressed ourselves to the structure, stabi lity and energetics of some singular and non-singular topological defe cts, and certain director configurations. We find that certain nonsing ular hybrid disclinations could be energetically favourable relative t o certain half-strength disclinations. The interaction between singula r hybrids depends strongly on the biaxial elastic anisotropy. We sugge st possible defect structures that can exist in spherical droplets of biaxial nematics. Further we find structural instabilities, in confine d geometries, arising due to the inherent biaxiality of the system.