Effects of Ba and Ti co-doping on BiFeO₃ multiferroic ceramics optimized through two-step doping

Ceramics of Bi_0.9Ba_0.1Fe_0.925Ti_xO₃ (x = 0.0625, 0.08125, 0.0875, and 0.11) were prepared according to two doping strategies: one is called single-step doping in which Ba and Ti were doped together in calcination, while the other one is called two-step doping in which Ba and Ti were doped in calcination and sintering, respectively. Compared with samples prepared with single-step doping, those prepared with two-step doping have obviously different XRD patterns and small grains, and are dramatically improved in dielectric loss, resistivity, and remnant magnetization. A low dielectric loss of 0.05 at 10³ Hz, a high resistivity of 4×10¹² Ω·cm, and a large remnant magnetization of 1.5 emu/g, have been obtained simultaneously for Bi_0.9Ba_0.1Fe_0.925Ti_0.11O₃ prepared with two-step doping. The contrast between these two doping strategies clearly reveals the importance of establishing a proper doping strategy when two or more elements are co-doped to BiFeO₃.