Dielectric Properties of Ferroelectric Rb₂CoCl₄

Abstract

Phase transition temperatures of single crystals of Rb 2 CoCl 4 prepared by the Bridgman method were checked by a DTA technique and a dielectric measurement and it was found that the Curie temperature T C is -74°C and the normal-incommensurate transition point T i is 21°C on heating. The thermal anomaly at the Curie temperature T C was observed by the DTA technique with a Ge–Ag thermocouple. The temperature dependence of the dielectric constants in the b and c directions was measured in a temperature range covering these phase transition points and the temperature dependence of P s and E c was determined from the observed 50 Hz D - E hysteresis loop, respectively. It was determined that the ferroelectric axis of Rb 2 CoCl 4 is the a axis in reality.