The Phenomenological Considerations of the Electric Field Induced Transitions in Improper Ferroelectrics and Ferroelastics. II

抄録

The electric-field effects on the transitions in the improper ferroelectrics are discussed on the basis of the Landau-type thermodynamic potentials. The phase diagrams in the electric field vs temperature are drawn in the cases where the high temperature normal phase is not piezoelectric and the transition from it is of the first order. The qualitative difference in the obtained phase diagrams in the present and the previous paper is mentioned. The anomalies in the temperature dependence of transition parameters, the electric susceptibility and the elastic constant are discussed.