Two dielectric contributions due to domain/cluster structure in the ferroelectrics with diffused phase transitions

Abstract

The main dielectric contributions and the structure of dielectric spectrum of the ferroelectrics with diffused phase transitions are considered on the base of PbMg_1/3Nb_2/3O₃ (PMN) crystals investigation. Dielectric spectra of the displacive, order-disorder and diffused phase transitions ferroelectrics are compared. Dielectric properties of the PMN are nontypical for displacive-type ferroelectrics and aren't defined mainly by soft phonon mode. The main polarization mechanisms are caused by the thermoactivated dynamics of the metastable polar phase clusters and polar - nonpolar phase boundaries.