Simple method for confirming the antiferroelectric structure of smectic liquid crystals

Abstract

Schlieren texture has been observed in S_c and S_CA liquid-crystalline phases. We found that defects of strength s=± 1/2 exist in the S_CA phase in addition to those of s=± 1 observed in the S_c phase. The existence of the s=± 1/2 wedge disclination is explained by taking account of a screw dislocation. This complex defect consisting of a wedge disclination and a screw dislocation, i. e. a dispiration, serves as a simple test to confirm the antiferroelectric (S_CA) structure.