Electrical, optical, electro-optical and electro-mechanical properties of liquid crystals in freely suspended films and in periodic three-dimensional array of nano-scale voids in synthetic opals

Pyroelectric effect has been observed in freely suspended film (FSF) of ferroelectric liquid crystal (FLC). The temperature dependence of spontaneous polarization evaluated using this effect has been found to be nearly the same as that in the sandwich cell. In the FLC FSF no threshold has essentially been observed in the electro-optic effect. On the other hand, in transferred film (TF) the threshold exists even at extremely slow scan rate. The threshold field is found to increase with decreasing thickness of TF. In the case of TF the substrate influences strongly the electro-optic effect. The influence of the substrate was found to extend to about 200 smectic layers. Upon acoustic sound irradiation and also electric field application on FLC FSF, the mechanical vibration of the film was effectively excited. For both excitations, resonance vibrations were observed but their oscillating modes were different. The application of FLC FSF to a space electric field sensor has also been discussed. Unique electrical and optical properties of liquid crystals infiltrated in nano-scale voids of synthetic opals with three-dimensional regular array have also been observed.