Electromechanical responses of antiferroelectric and ferrielectric liquid crystals

We measured the electromechanical responses in the antiferroelectric and ferrielectric phases of the prototype antiferroelectric material (R)-MHPOBC. Our observations confirm recent results, which indicated that SmCbeta* is ferrielectric, or at least not normal ferroelectric. In addition, we found that the layers become permanently tilted after dc field treatments. The mechanical responses are practically zero normal to the plates due to mechanical compensation of the electroclinic effect. This fact may have an importance in display applications, since a vertical vibration usually disturbs electro-optical performances. (C) 1999 American Institute of Physics. [S0021-8979(99)00102-4].