Structural evolution and enhanced magnetization of Bi_1-xPr_xFeO₃

The structural, ferroelectric, vibrational, and magnetic properties of polycrystalline Bi_1-xPr_xFeO₃ (0≤x≤0.50) powders are investigated by the measurements of X-ray diffraction, X-ray photoelectron spectroscopy, Raman scattering spectroscopy, and magnetization at room temperature. Our results reveal that the rare-earth ion Pr substitution at Bi site causes the structural transformations from rhombohedral R3c phase to orthorhombic Pbam phase at x≈0.15, and then to orthorhombic Pnma phase at higher Pr concentration x≈0.25, accompanying the ferroelectric-antiferroelectric-paraelectric phase transition. Measurements of magnetic properties confirm that Pr substitution can improve the magnetization of BiFeO₃ before approaching the first phase transition. We find that an inverse behavior occurs after passing a maximum across the antiferroelectric-paraelectric phase boundary. We also obtain the unique switching behavior in low magnetic field of Bi_0.5Pr_0.5FeO₃ from the field dependence on magnetization, indicating the existence of the antiferromagnetic ordering.