Effect of Co-Doping on Magnetic Properties of Bismuth Ferrite

The effect of co-doping on structure and magnetic properties of the BiFeO3-based multiferroics with a partial isovalent substitution of bismuth for La3+, Gd3+, Dy3+, and Er3+ ions have been experimentally investigated by X-ray diffraction and magnetic methods. The ceramic R1(x)R2(0.2-x)Bi(0.8)FeO(3) type (x = 0, 0.05, 0.10, 0.15, 0.20; R1, R2 = La, Gd, Dy, Er) samples have been prepared by a solid-state reaction method under cold pressing at high pressure P = 4 GPa. Temperature dependences of magnetization for the co-doped BiFeO3 demonstrate magnetic "weak ferromagnetic-antiferromagnetic" phase transitions in a high temperature range T = 550-650 K. The presence of a weak ferromagnetism in all compositions is confirmed by open loops of magnetic field dependences. It has been found out that the magnetic characteristics strongly depend on the degree of substitution, temperature, and magnitude of magnetic field.