Uniaxial and biaxial lyotropic nematic liquid crystals

Abstract

Experimental evidence for the existence of optically biaxial lyotropic nematics is presented. The first experimental measurements of the optical uniaxial birefringence $\ensuremath{\Delta}n$ versus the temperature in a discotic nematic are reported; they show a discontinuity of $\ensuremath{\Delta}n$ at the discotic-calamitic phase transition.