Observation of Three Subphases in Smectic C* of MHPOBC by Dielectric Measurements

Abstract

In the phase transition from the paraelectric smectic A to the antiferroelectric SmC_A ^* phase via the ferroelectric SmC^* phase in MHPOBC, the existence of a subphase, SmC_α ^*, between SmA and the normal SmC^* (SmC_β ^*) was confirmed in addition to that of another subphase, SmC_γ ^*, between SmC^* and SmC_A ^* by means of dielectric measurements. It was also confirmed that these subphases, SmC_α ^* and SmC_γ ^*, disappear in the same compound of lower optical purity as observed by DSC. The model structure of the SmC_α ^* phase is speculated on the basis of the dielectric measurements.