X-Ray Study of the Hexatic-B-to-Smectic-APhase Transition in Liquid-Crystal Films

Abstract

X-ray studies of thick, free-standing films of the liquid-crystal compound $n$-butyl 4′-$n$-hexyloxybiphenyl-4-carboxylate (46OBC) have determined the critical behavior at the three-dimensional hexatic-$B$-to-smectic-$A$ phase transition. The position and width of the scattering peaks exhibited $1-\alpha$ singularities in agreement with theory and heat-capacity results. Measurements on two-layer films of 46OBC provided evidence for a continuous, two-dimensional, hexatic-to-liquid transition.