On the Slater-Takagi Model of the Ferroelectric Phase Transition in KH₂PO₄ —Role of the Takagi Configuration—

Abstract

The Slater-Takagi model of the ferroelectric phase transition in KH₂PO₄ is analyzed in detail. The transition is of the second order not only for partial removal but also for complete removal of the ice condition on proton distributions, as has been clarified by Silsbee et al. The free energy and the spontaneous polarization are given explicitly as functions of temperature. The role of the Takagi configuration is discussed.