Dielectric and Thermal Study of K2SeO4 Transitions

TLDR: In this article, the Curie temperature varies almost linearly with the biasing field with the coefficient of 0.19°/kV/cm, while the spontaneous polarization and coercive field determined from the hysteresis loop are 6.5×10 -8 coul/cm 2 and 60 V/cm respectively at 80°K.

Abstract: The behaviours of the various dielectric properties and specific heat of potassium selenate, K 2 SeO 4 , have been studied with particular reference to the transitions at 129.5°K and 93°K. Below 93°K the crystal is ferroelectric along the c axis. The spontaneous polarization and coercive field determined from the hysteresis loop are 6.5×10 -8 coul/cm 2 and 60 V/cm respectively at 80°K. The curve of dielectric constant vs temperature obeys the Curie-Weiss law above the Curie point and the Curie constants for warming and cooling processes are 27°K and 30°K respectively. The Curie temperature varies almost linearly with the biasing field with the coefficient of 0.19°/kV/cm. Effects of the γ-radiation on the dielectric behaviour are observed. Discontinuity of the specific heat of about 2.3 cal/mol·deg has found at the transition of 129.5°K. Anomaly at the transition of 93°K is very small. The transition energy and the entropy change are estimated to be of the order of 0.5 cal/mol and 5×10 -3 cal/mol·deg of le...