Calculation of the spontaneous polarization and the dielectric constant as a function of temperature for KH 2 PO 4

Abstract

The temperature dependence of the spontaneous polarization P is calculated in the ferroelectric phase (T T C) of KDP at atmospheric pressure. For this calculation of P and ε, by fitting the observed Raman frequencies of the soft mode, the microscopic parameters of the pure tunnelling model are obtained. In this model, the proton-lattice interaction is not considered and the collective proton mode is identified with the soft-mode response of the system. Our calculations show that the spontaneous polarization decreases continuously in the ferroelectric phase as approaching the transition temperature T Also, the dielectric constant decreases with increasing temperature and it diverges in the vicinity of the transition temperature (T= 122 K) for KDP according to the Curie-Weiss law. © 2012 Hamit Yurtseven and Sema Şen.