Direct and inverse electromechanical effect in ferroelectric liquid crystalline elastomers

Ferroelectric liquid crystalline elastomers (FLCEs) form a novel class of materials, in which the properties of macroscopically oriented ferroelectric liquid crystals can be combined with those of elastomers. The (direct and the inverse) piezoelectric effect in these systems is measured and analyzed on a molecular level. Backed also by x-ray measurements, a model is suggested that interprets the observed piezoelectricity caused by electrically or mechanically induced motions of smectic layers which are inclined with respect to the sample surface. The strength of the observed electromechanical effects compares well with (or exceeds) that of classical piezoelectric materials like barium titanate, lead zirconate titanate or poled polymers like poly(vinylidene fluoride), making FLCEs an interesting candidate for applications in microsystems technology. (C) 1999 American Institute of Physics. [S0021-8979(99)06915-7].