Phase Transitions, Magnetic and Piezoelectric Properties of Rare‐Earth‐Substituted BiFeO3 Ceramics
The concentration range of the stability of polar (R3c) and antipolar phases in the Bi1−x
(RE–La ‐ Dy) solid solutions has been determined by X‐ray study of the polycrystalline samples. Both polar and antipolar phases become less stable with a decrease of the rare earth ionic radii. It is stimulated by a reduction of the rare‐earth ions polarizability
with a decrease in ionic radii. The antipolar phase is characterized by a weak ferromagnetic state, whereas the polar one exhibits dominantly antiferromagnetic behavior near the polar‐antipolar morphotropic boundary. The local piezoelectric response decreases with increase in antipolar
phase content in the mixed polar‐antipolar structural state. It is suggested that the piezoelectric activity is associated with polar (R3c) phase.