Ho and Ti co-doped BiFeO₃ multiferroic ceramics with enhanced magnetization and ultrahigh electrical resistivity

Bi_0.9Ho_0.1Fe_0.95O₃ and Bi_0.9Ho_0.1Fe_0.9Ti_0.05O₃ ceramics were prepared and compared to reveal the effects of Ho and Ti codoping in BiFeO₃. X-ray diffraction indicated that both ceramics had a high rhombohedral perovskite phase content, and microstructural analyses showed that the grains of the Bi_0.9Ho_0.1Fe_0.9Ti_0.05O₃ ceramics were much smaller than those of Bi_0.9Ho_0.1Fe_0.95O₃. An electrical resistivity of more than 1×10¹⁴ Ω·cm at room temperature, and a magnetic hysteresis loop with a remnant magnetization 2M_r of ～0.485 emu/g were obtained for Bi_0.9Ho_0.1Fe_0.9Ti_0.05O₃; both were much higher than those of Bi_0.9Ho_0.1Fe_0.95O₃. Changes in the defect subsystem of BiFeO₃ induced by Fe-deficiency and (Ho,Ti) codoping are proposed as being responsible for the improvement in the properties.