Enhancement of Ferromagnetic and Ferroelectric Properties in Codoped BiFeO3

Abstract

Co-doped insulating Bi_0.8La_0.2Fe_1-xMn_xO₃, (x = 0, 0.1) ceramics were prepared by conventional solid state reaction method. The XRD study shows that 20 % substitution of La ions changes the structure from rhombohedral (space group R3c) that of BaFeO₃ to the orthorhombic (C222) for Bi_0.8La_0.2FeO₃ (BLFO). For further substitution of Mn-ions in Fe-site no structural change occurs. From DTA and TGA study, it is observed that magnetic transition temperature (T_m) decreases appreciably whereas ferroelectric transition temperature (T_C) does not affect much with the increase of Mn-concentration. The magnetization-magnetic field measurements show that increase of magnetization for co-doping of La and Mn in Bi_0.8FeO₃ is due to the destruction of the spin cycloid structure in it and the introduction of the mixed valance state. P-E measurement shows the ferroelectric nature of the sample.