Abstract
The antiferroelectric smectic- (Sm-) phases of two closely related chiral compounds have been studied with high-resolution calorimetric techniques. Both methylheptyloxycarbonylphenyl octyloxybiphenyl carboxylate (MHPOBC) and its octylcarbonylbiphenyl analog (MHPOCBC) exhibit Sm- and Sm- antiferroelectric phases. The Sm-A–Sm- transitions are mean-field second order and well described by the usual extended Landau model. Three restructuring Sm- transitions in MHPOBC studied with a relaxation calorimeter are shown to be sharp first-order transitions with very small latent heats. Pretransitional heat capacity associated with the Sm-–Sm- (hexatic smectic-) transition and freezing of the monotropic Sm- phase was studied in MHPOCBC.
- Received 8 September 1992
DOI:https://doi.org/10.1103/PhysRevE.47.1203
©1993 American Physical Society