High-resolution birefringence study at the nematic-smectic A phase transition of ZnS nano particle dispersed octyloxycyanobiphenyl

Abstract

We have studied the effect of ZnS nano particles with different concentrations on the nematic to smectic A (N-SmA) phase transition of a thermotropic liquid crystal octyloxycyanobiphenyl (8OCB). These effects are probed using a high resolution optical birefringence measurement. A decreasing trend of the nematic range of 8OCB has been observed up to a certain limit with increasing concentrations of the guest nano particles. A simple power law analysis has been carried out to extract the critical exponent (α) at the N-SmA phase transition, which allows one to investigate the critical behaviour near the phase transition as well as the universality class. The critical exponent (α) at the N-SmA phase transition strongly indicates the change in the coupling strength between the nematic and smectic A order parameters.