The magnetoelectric coupling in rhombohedral-tetragonal phases coexisted Bi _(0.84)Ba _(0.2)0FeO _3

摘要

Ba doped Bi _(1.04-x)Ba _xFeO _3 ceramics with x up to 0.30 have been prepared by the tartaric acid modified sol-gel method. The X ray diffraction patterns show that the structure transforms from rhombohedral to tetragonal with increasing the Ba substitution concentration from 10% to 30% and the coexistence of distorted rhombohedral and tetragonal phases in 20% Ba substituted BiFeO _3, which was further confirmed by the Raman spectra. Bi _(0.84)Ba _(0.20)FeO _3 exhibits the highest magnetization (1.6 emu/g under magnetic field of 12 kOe) compared with the other samples of different Ba substitution concentration. Significant enhancement of the ferroelectricity has been observed in 20% and 30% Ba substituted BiFeO _3 with saturate polarization close to 6.6 μC/cm ~2 for Bi _(0.74)Ba _(0.30)FeO _3. The magnetoelectric coupling of Bi _(0.84)Ba _(0.20)FeO _3 has been measured and the maximum decrease of magnetization under magnetic field of 9.8 kOe was about 0.06 emu/g with increasing applied electric field to 11 kV/cm, and the magnetoelectric coefficient is 1.5×10 ~(-12) s/m.