Effect of Alkaline-earth Metal Ions Doping on the Multiferroic of BiFeO₃ Ceramics

To investigate the effect of alkaline-earth metal doping on the multiferroic of BiFeO₃ ceramics, BiFeO₃ and Bi_0.9A_0.1FeO₃(A=Ca, Sr, Ba) ceramics were successfully prepared by solid phase method, and their ferroelectric as well as ferromagnetic properties were studied. XRD results showed that all samples could be indexed to be the hexagonal perovskite structure with space group R3c. The lattice parameters increase first and then decrease with the increase of the radius of doping ions. Electrical measurements showed that ferroelectric polarization as well as leakage current density of Bi_0.9A_0.1FeO₃ ceramic increases with increasing the radius of doping ions. Taken the XPS analysis into account, we conclude that both structure distortion and the change of oxygen vacancy concentration impact the ferroelectric properties. Under a magnetic field of 14 T the magnetizations of BFO, BCFO, BSFO, BBFO ceramic are around 0.150, 0.356, 0.497 and 0.995 emu/g, respectively. The distortion of the antiferromagnetic structure and the variation of the Fe ions in Bi_0.9A_0.1FeO₃ ceramics are responsible for the enhancement of the ferromagnetism.