Linear electromechanical effect in free-standing ferroelectric liquid-crystalline films

Mechanical oscillations of free-standing films based on ferroelectric liquid crystals were studied by optical methods. The intrinsic oscillation modes in the samples were excited by applying an alternating electric field parallel to the film surface. The surface viscosity of the films determined using the electromechanical effect was ηs=8.8×10−3 g/s under normal pressure and ηs=1.5×10−3 g/s in vacuum. The surface tension measured in a special experiment was σ=35.3 din/cm. It was established that the spectrum of mechanical oscillations in the system studied is affected by the vapors of volatile organic solvents such as kerosene, toluene, and ethyl alcohol. The linear electromechanical effect in the free-standing films was used to observe inversion of the sign of spontaneous polarization in a ferroelectric liquid crystal.