High-pressure study of a reentrant isotropic phase

The boundary between the isotropic phase and the $N_L$ lyotropic nematic phase in a mixture of potassium laurate, ${\mathrm{D}}_2$O, and decanol has been mapped as a function of pressure and temperature. The nematic region is found to be surrounded by an isotropic region in the P-T plane, demonstrating conclusively that the isotropic phase seen at lower temperatures in this system is indeed a reentrant phase. At the phase transition the density of the nematic phase is found to be always less than that of the isotropic liquid.