Enhanced dielectric and multiferroic properties in BaTiO₃ doped Bi_0.85Nd_0.15Fe_0.98Mn_0.02O₃ ceramics

The multiferroic ceramics of (1-x) Bi_0.85Nd_0.15Fe_0.98Mn_0.02O₃-x BaTiO₃ (x = 0, 0.275, 0.3 and 0.325) were prepared by the conventional solid phase reaction. The crystal structure, microstructure, dielectric, ferroelectric and magnetic properties were systematically investigated. The X-ray diffraction pattern indicates that the structure of Bi_0.85Nd_0.15Fe_0.98Mn_0.02O₃ is rhombohedral and the space group is R3c. Rietveld refinement shows that with the introduction of BaTiO₃, the crystal structure of the material transformed from rhombohedral (R3c) to pseudo-cubic (P4mm). Scanning electron microscopy analysis shows that the average grain size decreases with the introduction of BaTiO₃. Temperature dependence of the dielectric constant and the dielectric loss indicate that the introduction of BaTiO₃ leads to ferroelectric relaxation. The dielectric constant and the dielectric loss are improved in sync. The leakage current density is reduced by about two orders of magnitude under the electric field of 15 kV/cm. The ferroelectricity and ferromagnetism are greatly improved after the addition of BaTiO₃ seen from the polarization hysteresis (P-E) loops and the magnetization hysteresis (M-H) loops.