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

BiFeO3, 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 X 10(14) Omega cm, BiFe0.9Ti0.05O3 ceramic displays an especially low dielectric loss, 0.015 at 100 Hz, a remanent polarization P-r of 0.23 mu C/cm(2) and a remanent magnetization M-r 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. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3506526]