Pressure Study of a Hexatic B and Crystal B Phase

Abstract

Pressure temperature phase diagrams of two compounds exhibiting smectic B phases are presented. In one compound, the smectic B phase is liquid (no long range positional correlations) and is called a hexatic B phase, whereas in the other the smectic B phase is crystalline in nature. “Transition bars”, which are often observed at a smectic A to crystal B transition are observed above 1.5 kbar (and not below) in the former compound and the smectic A phase appears quite piezo-resistant. In contrast, for the latter compound, the smectic A phase disappears above 1.94 kbars. These results suggest that the two smectic phases are stabilized by different forces and we suggest a model.