Enhanced multiferroic characteristics in NaNbO3-modified BiFeO3 ceramics

Modification of BiFeO3 multiferroic ceramics were investigated by introducing NaNbO3 to form (Bi1-xNax)(Fe1-xNbx)O3 (x =0.1, 0.3, and 0.5) solid solutions. With increasing NaNbO3 content, the crystalline structure changed and the ferroelectric properties were improved. The significantly reduced leakage resulted in more regular ferroelectric hysteresis loop for all compositions. Dielectric characteristics of (Bi1-xNax)(Fe1-xNbx)O3 (x =0.1, 0.3, and 0.5) ceramics were evaluated. Two dielectric relaxations were observed in the temperature ranges of 550-600 and 650-710 K in (Bi0.9Na0.1)(Fe0.9Nb0.1)O3 ceramics, and the higher-temperature dielectric relaxation was related to the antiferromagnetism transition, which indicated the coupling between the ferroelectric and magnetic orders essential for the multiferroic materials. Moreover, weak ferromagnetism with remnant magnetization (M_r) of 0.14 emu/g and coercive field (H_c) of 6.48 kOe were observed in the sample with x =0.1, which suggested that the present modified ceramics had enhanced multiferroic characteristics.