Dynamic critical behavior of thermal parameters at the smectic-A-nematic phase transition of octyloxythiolbenzoate

The dynamic as well as the static critical behavior associated:with the thermal parameters was investigated over the smectic-A- nematic phase transiton of octyloxythiolbenzoate ((8) over bar S5) through the simultaneous determination of the specific heat, thermal conductivity, and thermal diffusivity obtained by the photopyroelectric technique. The critical exponent of the specific heat is close to the one predicted for three-dimensional XY like (n = 2,d = 3) transitions, such as the superfluid transition in helium. A dip in the diffusivity was observed and the critical exponent results were consistent with a dynamic model, also with n = 2 and d = 3, which considered dissipative couplings between the order parameter and the conserved energy density in the free energy functional. A smooth thermal conductivity has been obtained over the transition temperature.