Abstract
A T-E phase diagram of MHPOBC (C8H17O–
--COO–-COO*CH(CH3)C6H13) has been obtained by means of the temperature (T) dependence of the dielectric constant under a dc biased electric (E) field. It is presumed from the T-E phase diagram that there is a temperature range where the field-induced antiferroelectric-ferrielectric-ferroelectric phase transitions take place. These transitions have been confirmed as five transmittance states between crossed Nicols under a triangular wave, i.e., ferro-ferri-antiferro-ferri-ferro. The field-induced antiferroelectric-ferrielectric phase transition has also been identified through conoscopic observation.