抄録
By the use of the analogy between the self-consistent phonon theory and the self-consistent renormalized spin fluctuation theory on itinerant electron ferromagnets, the Curie-Weiss susceptibility in displacive-type ferroelectrics is shown to consist of two different mechanisms, (a) the decrease in the mean square amplitude of the soft mode and (b) the increase in the correlation between dipoles. The ratio of the paraelectric moment to the saturated moment is calculated from experimental data in typical ferroelectrics. The great deviation of this ratio from unity in displacive-type ferroelectrics is shown to be attributed to the mechanism (a), and the appearance of the relaxation mode in dynamical spectra to (b).
