Study of liquid crystalline phases from temperature dependent dielectric constant

Derivative of the static dielectric constant (epsilon) with inverse tempera ture (I/T) is a sensitive technique to determine the liquid crystalline pha ses. According to Maier and Meier theory (Maier & Meier, Z Naturforsch, 16A (1961) 262), epsilon can be written as A + B/T. Plots of B = d epsilon/d(I /T) [which is the function of molecular density (N), order parameter (S) an d dipole-dipole correlation factor (g)] with T show peaks at the transition temperatures, and the values of B give an estimate of the nature and magni tude of dipolar correlation in different mesophases. The technique has been applied to determine the transition temperatures of six liquid crystalline materials by their temperature dependent dielectric data.