화학공학소재연구정보센터
Molecular Crystals and Liquid Crystals, Vol.682, No.1, 1-7, 2019
Electric-field-induced transition from SmA to ferroelectric SmC* in MC881, where antiferroelectric SmCA* but not SmC* emerges just below SmA
We studied the electric-field-induced tilt angle in SmA of MC881 and found the field-induced, first-order phase transition to SmC* in the SmA temperature region just above temperature-induced antiferroelectric SmCA*. The similar field-induced first-order transition from SmA to SmC* was observed by Bahr and Heppke [1, 2] in a compound called C7, where the temperature-induced first-order SmA to SmC* transition occurs. Here in MC881, on the contrary, no temperature-induced SmC* emerges just below SmA; instead temperature-induced antiferroelectric SmCA* is produced directly by the first-order phase transition from SmA. So far as we know, this is the first observation of the field-induced first-order phase transition from SmA to SmC* in the SmA-SmCA* phase sequence. We also confirm a large increase in the field-induced birefringence in SmA near the transition temperature to SmCA*, which was once ascribed by Manna et al. [3] to the existence of de Vries-type SmA. We are now considerably skeptical about their view because of the clear observation of the first-order field-induced transition from SmA to SmC*.