Nonstoichiometric BiFe0.9Ti0.05O3 multiferroic ceramics with ultrahigh electrical resistivity

BiFeO 3 , BiFe0.9Ti0.1O3, and BiFe0.9Ti0.05O3 ceramics of relatively high perovskite phase content were prepared for a comparison study. While both BiFe0.9Ti0.1O3 and BiFe0.9Ti0.05O3 exhibit similarly improved weak ferromagnetism over BiFeO3, there exists a major difference in the x-ray diffraction patterns of BiFe0.9Ti0.1O3 and BiFe0.9Ti0.05O3, and the leakage current of BiFe0.9Ti0.05O3 is decreased by five orders of magnitude from that of BiFe0.9Ti0.1O3. With an ultrahigh electrical resistivity, over 1×1014 Ω cm, BiFe0.9Ti0.05O3 ceramic displays an especially low dielectric loss, 0.015 at 100 Hz, a remanent polarization Pr of 0.23 μC/cm2 and a remanent magnetization Mr of 0.13 emu/g at room temperature. It is proposed that the Fe-deficiency in BiFe0.9Ti0.05O3 decreases the amount of Fe2+ and leads to the ultrahigh electrical resistivity. Nonstoichiometric compositions should receive more attention for developing high quality BiFeO3 multiferroic materials.