Effect of different concentrations of dopant titanium dioxide nanoparticles on electro-optic and dielectric properties of ferroelectric liquid crystal mixture

In the present study, the insulating titanium dioxide (TiO2) nanoparticles were dispersed in two different concentrations of 0.5 wt % and 1.0 wt % in pure ferroelectric liquid crystal (FLC) mixture, W206E. The effects of different concentrations of dopant TiO2 in W206E for electro-optical and dielectric properties have been studied. The optical microscopy measurements clearly show the isotropic transition temperature of both the doped samples slightly increases by about 1 ~ 2 0 C as compared to the pure sample. Further, with the increasing concentrations of dopant TiO2, the value of spontaneous polarization decreases. The value of dielectric permittivity also decreases for both the doped samples and this decrease in the value of permittivity is more prominent with increasing concentrations of TiO2 at the lower frequencies. The dielectric measurements also confirm the presence of Goldstone mode in Smectic C* phase in pure as well as in both the doped samples. The conductance measurements confirm the decrease in conductivity of doped samples as compared to the pure W206E FLC. This study may help in improving the transition temperature and reducing the impact of free ionic charge impurities on various physical properties of liquid crystal host by screening the free ions using TiO2 nanoparticles as dopant. Copyright © 2016 VBRI Press.