Characterization of the smectic-A-hexatic-B transition in 65OBC by adiabatic scanning calorimetry
Laboratorium voor Akoestiek en Thermische Fysica, Departement Natuurkunde en Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001, Leuven, Belgium
* e-mail: Bert.VanRoie@fys.kuleuven.ac.be
Accepted: 14 January 2005
Published online: 7 February 2005
We investigated the smectic-A-hexatic-B (SmA-HexB) transition in the liquid-crystal n-hexyl-4’-n-pentyloxybiphenyl-4-carboxilate (65OBC) with adiabatic scanning calorimetry. We were able to prove in a direct way that this transition is indeed very weakly first order, as was already suggested in the literature. The latent heat at the transition was determined to be ΔH L = 0.04±0.02 J/g. Our experiments confirm the high value for the heat capacity critical exponent earlier reported, yielding α = 0.64±0.05.
PACS: 64.70.Md Transitions in liquid crystals – / 64.60.Fr Equilibrium properties near critical points, critical exponents – / 65.20.+w Thermal properties of liquids: heat capacity, thermal expansion, etc. –
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2005