X-ray studies of the hexatic phase in liquid crystals with a crystal-<i>B</i>–hexatic-<i>B</i>–smectic-<i>A</i>phase sequence

Abstract

Free-standing monodomain thick films of three liquid crystalline compounds were examined by x-ray scattering. These compounds exhibit a unique enantiotropic crystal-B--hexatic-B--smectic-A phase sequence with no evidence of herringbone order. The hexatic order parameter ${\mathit{C}}_{6}$ changes in the hexatic phase with critical exponent \ensuremath{\beta}=0.15\ifmmode\pm\else\textpm\fi{}0.03. Temperature dependence of the in-plane positional order correlation length suggests a strongly first-order hexatic-B to crystal-B phase transition with indiscernible enthalpy change.