Stability of Field-Induced Phase Transitions in PMN-PT Compositions near the Morphotropic Phase Boundary

The properties of the relaxor ferroelectric PbMg_1/3Nb_2/3O₃ (PMN) can be controlled by adding PbTiO₃ (PT) ferroelectric, which forms a solid solution with PMN. With the concentration of PT around ~0.33, the composition reaches the morphotropic phase boundary (MPB) between relaxor and ferroelectric behavior. In the vicinity of the MPB, PMN-PT shows maximum dielectric and piezoelectric properties. By applying an electrical field, we can induce macroscopic polarization in PMN-PT as it transitions to the ferroelectric state. Different regimes of field applications show very different dynamics of the relaxor to ferroelectric transition. We also found that this transition in PMN-PT close to the MPB depends on the magnitude of the field as well as the electrical prehistory of the sample (cooling-heating rate, protocol of the field application, etc.). This could indicate competition between glassy disorder and the applied field in ordering the macroscopic polarization.