Electrostrictive Corrections to the Pseudo One-Dimensional Ising Model of Ferroelectrics

抄録

The electrostrictive corrections have been made to a previous theory based on the pseudo one-dimensional Ishing model. The corrected results explain well the dielectric and the heat-capacity data of CsD₂PO₄ (d-CDP) both in the para- and ferroelectric phases even without the proton-tunnelling terms, but they are not so successful in the case of CsH₂PO₄ (CDP). The ratio of the effective dipole moments which indicates the strength of the effect of proton-tunnelling [Levstik et al.: J. Phys. C19 (1986) L25] is evaluated as μ_ε⁄μ_p=1.2 for CDP. This value suggests that, in CDP, the tunnelling-effect cannot be neglected.