Structural, raman, dielectric, magnetic and magnetoelectric properties of Ba and Mn doped BiFeO3 nanoparticles

Ba and Mn doped BiFeO₃ nanoparticles were synthesized by sol-gel method. X-ray diffraction and Raman spectroscopy results showed the presence of distorted rhombohedral structure for Bi_0.85Ba_0.15FeO₃ nanoparticles and the substitution induced phase transition (rhombohedral to orthorhombic) phase for Bi_0.85Mn_0.15FeO₃ nanoparticles. FESEM images of both the samples revealed grain size in the range from 50 to 100 nm. Magnetic measurement showed room temperature ferromagnetic behavior, which may be attributed to the antiferromagnetic core and the ferromagnetic surface of the nanoparticles, together with the structural distortion caused by Ba and Mn substitution in BiFeO₃ samples. The magnetoelectric coupling was evidenced by the observation of the dielectric anomaly in the dielectric constant near antiferromagnetic Neel temperature in both the samples.