Nonstoichiometric BiFe₀.₉Ti₀.₀₅O₃multiferroic ceramics with ultrahigh electrical resistivity

Abstract

BiFeO₃, BiFe₀.₉Ti₀.₁O₃, and BiFe₀.₉Ti₀.₀₅O₃ceramics 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 BiFe₀.₉Ti₀.₁O₃and BiFe₀.₉Ti₀.₀₅O₃ , and the leakage current of BiFe₀.₉Ti₀.₀₅O₃is decreased by five orders of magnitude from that of BiFe₀.₉Ti₀.₁O₃. With an ultrahigh electrical resistivity, over 1 x 10¹⁴Ωcm, BiFe₀.₉Ti₀.₀₅O₃ ceramic displays an especially low dielectric loss, 0.015 at 100 Hz, a remanent polarization Pힲ of 0.23 μC/cm² and a remanent magnetization Mힲ 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.