Effect of Gd doping on structural, electrical and magnetic properties of BiFeO3 electroceramic

Room temperature multiferroic electroceramics of Gd doped BiFeO3 monophasic materials have been synthesized adopting a slow step sintering schedule. Incorporation of Gd nucleates the development of orthorhombic grain growth habit without the appearance of any significant impurity phases with respect to original rhombohedral (R3c) phase of un-doped BiFeO3. It is observed that, the materials showed room temperature enhanced electric polarization as well as ferromagnetism when rare earth ions like Gd doping is critically optimized (x=0.15) in the composition formula of Bi1+2xGd2x/2Fe1−2xO3. We believe that magnetic moment of Gd+3 ions in Gd doped BiFeO3 tends to align in the same direction with respect to ferromagnetic component associated with the iron sub lattice. The dielectric constant as well as loss factor shows strong dispersion at lower frequencies and the value of leakage current is greatly suppressed with the increase in concentration of x in the above composition. Addition of excess bismuth and Gd (x=0.1 and 0.15) caused structural transformation as well as compensated bismuth loss during high temperature sintering. Doping of Gd in BiFeO3 also suppresses spiral spin modulation structure, which can change Fe–O–Fe bond angle or spin order resulting in enhanced ferromagnetic property.

► Impurity peaks of BiFeO3 suppressed with the increase of x (x=0.15) in Bi1+2xGd2x/2Fe1−2xO3. ► Structural phase transformation takes place from R3C to Pn21a when Gd is incorporated. ► Gd doped BFO suppresses spiral spin modulation, which in turn favors ferromagnetism. ► Leakage current suppressed significantly for x=0.15 in Bi1+2xGd2x/2Fe1−2xO3. ► Strong response of K and tan δ at low frequency comes from dipolar and interfacial polarization.