STUDY OF THE NEMATIC ELECTROCLINIC EFFECT IN MIXTURES

The temperature dependence of the nematic electroclinic effect has bee n studied in binary mixtures prepared from two chiral compounds with n ematic-smectic A-smectic C and nematic-smectic C phase sequences. The data obtained show a substantial difference in the magnitude of the ef fect, not only with the type of phase sequence, but also with the temp erature range of the subsequent smectic A phase. These results suggest that short-range smectic fluctuations can play an important role in t he nematic electroclinic effect at least when a smectic C phase is clo se to the nematic. In addition, the dynamic behaviour of the electrocl inic effect has been investigated in the compound with the nematic-sme ctic A transition. As in previous work, an anomaly in the electroclini c response time has been found around the nematic-smectic A transition . This fact is analysed qualitatively assuming two different mechanism s contributing to the electroclinic effect.