Anomalous Temperature Dependence of the Elastic Constant B at the Smectic-to-Nematic Phase Transition in Binary Mixtures of Hexyloxycyanobiphenyl-Octyloxycyanobiphenyl (60CB-80CB)

In hexyloxycyanobiphenyl-octyloxycyanobiphenyl (60CB-80CB) binary mixtures displaying reentrant behavior, the smectic elastic constant, B, deviates from a simple power law of the form B=B₁(TNA-T)^φ and levels off as T→TNA. This behavior is consistent with the Nelson-Toner dislocation-unbinding model of the transition.