Effect of the hexatic-Btemperature range on the nature of the smectic-A–hexatic-Bphase transition

High-resolution heat-capacity measurements have been carried out on several pure compounds and binary mixtures in the homologous series of n-alkyl-4'-n-decyloxybiphenyl-4-carboxylate. The measured smectic-A--hexatic-B heat-capacity anomalies can be fitted to a power law over two decades in the reduced temperature with a large value for the critical exponent ({α}=0.60). The value of {α} remains fairly constant when the hexatic-B phase temperature range varies from 0.8 to 22 K.