Detailed heat-capacity studies have been carried out in the vicinity of the smectic-C–smectic-I transition of two liquid-crystal compounds in the homologous series of racemic 4-(2’-methylbutyl)phenyl-4’-n-alkyloxybiphenyl-4-carboxylate (2M4PmOBC or mOSI). In contrast to the continuous smectic-A–hexatic-B transition found in many members of n-alkyl-4’-n-alkyloxybiphenyl-4-carboxylate (nmOBC) with symmetric and sharp heat-capacity anomalies, asymmetric and rounded ones are observed in the smectic-C–smectic-I transitions of both 2M4P8OBC and 2M4P9OBC.

• Received 6 November 1987

DOI:https://doi.org/10.1103/PhysRevA.37.3963