Freedericksz transition in a dual-frequency nematic liquid crystal

The Freedericksz transition was investigated in a dual-frequency liquid crystal consisting of a mixture of 2-chloro-4-(4-pentylbenzoyloxy)benzoate and N-(4-methoxybenzylidene)-4-butylaniline, in which dielectric anisotropy strongly depends on the frequency of the applied ac electric field. Because the threshold voltage for the transition from an undistorted state of orientation to a distorted one is a function of the dielectric anisotropy and of the Frank elastic constants, the threshold voltage was expected to depend on the frequency. The threshold voltage increased steeply as the frequency approached the crossover frequency at which the dielectric anisotropy vanished and the threshold voltage eventually diverged. Furthermore, we examined the Freedericksz transition under ac voltages of two different frequencies.