Effect of Ba doping on magnetic and dielectric properties of nanocrystalline BiFeO₃ at room temperature

Ba doped BiFeO₃ nanocrystallines were prepared by a sol-gel method. The crystal structure and morphology of the prepared samples were characterized using X-ray diffraction analysis and transmission electron microscope, respectively. The results showed that the lattice structure of the nanocrystallines transformed from rhombohedral to tetragonal with Ba substitution increased and the average grain size of the prepared samples lay in the range of 20-70 nm. Dielectric properties and magnetic properties of the nanocrystallines were studied. Dielectric properties were measured up to high frequency ∼100 MHz. We found that suitable amount of Ba dopant was helpful to improve the dielectric properties of BFO and the nanocrystalline with 20% Ba doping on Bi sites had the best dielectric properties among the Ba doped nanocrystallines. Magnetic properties of the nanocrystallines were greatly improved due to the presence of oxygen deficiency and significant opening in the room-temperature M-H loop was observed with Ba substitution. All the nanocrystallines presented the high ratio of M_r/M from 0.462 to 0.594 and large coercivity from 3.92 to 5.16 kOe.