Smectic C to cubic phase transition of ANBC-22 and electric field effect

Abstract

We examined the influence of an alternating current (ac) electric field on the smectic C (SmC) to cubic (Cub) phase transition of 4'-n-docosyloxy-3'-nitrobiphenyl-4-carboxylic acid (ANBC-22). The most unexpected result is that even at a temperature 8 K below the previously determined zero-field transition temperature (TSmC-Cub = ca. 408 K) and without field, the SmC-Cub transition occurs after a very long induction time of several hours; it is suggested that the 'true' transition temperature, which is difficult to determine precisely, exists around 397 K. Between 408 and 397 K, the SmC-Cub transformation is governed by the strongly restricted nucleation and growth of the Cub phase in the precusory SmC phase. The role of the ac electric field on the transition is to promote the nucleation and to accelerate the growth rate, resulting in the apparent induction of the SmC-Cub transition between 408 and 397 K.