Tailoring the dielectric features of a cyanobiphenyl based liquid crystal using bismuth titanate (Bi₂Ti₂O₇/Bi₄Ti₃O₁₂) nanocomposite

We present the concentration and temperature dependent optical textures, and dielectric properties of bismuth titanate (Bi₂Ti₂O₇/Bi₄Ti₃O₁₂) (BT2/BT4) nanocomposite doped 4′-octyl-4-biphenylcarbonitrile (8CB) liquid crystal (LC) mixtures using polarizing optical microscope and dielectric spectroscopic techniques. The optical textures of pure 8CB and BT2/BT4 nanocomposite doped 8CB mixtures affirm a uniform dispersion of nanocomposite. Interestingly, the value of dielectric permittivity ( \(\varepsilon_{ \bot }^{\prime }\) ${\epsilon }_{\perp }^{\prime }$ ) is found to be higher for all mixtures as compared to pure 8CB. Moreover, the values of \(\varepsilon_{ \bot }^{\prime }\) ${\epsilon }_{\perp }^{\prime }$ and electrical conductivity are the highest for the 0.1 wt% mixture in the low frequency region (20 to 100 Hz). These changes are attributed to the fact that both concentration and diffusion coefficient of mobile ions collectively control the dielectric parameters in the lower frequency region. The threshold voltage of N phase of 0.1 wt% BT2/BT4 nanocomposite doped 8CB mixture is found to be higher as compared to pure 8CB and the observed change is attributed to the ion releasing effect of the doped nanocomposite in the 8CB matrix.