Effect of Nb substitution on the structural, dielectric and magnetic properties of multiferroic BiFe1−xNbxO3 ceramics

Highlights: ► Effect of Nb5+ ion doping in structure, dielectric and magnetic properties of multiferroics BiFeO3 was studied. ► The result suggests the limit of dissolubility of Nb5+ ions in BiFeO3. ► The lowering of dielectric loss tangent by Nb5+ addition in the measured temperature range suggesting the control of oxygen vacancy and improved resistivity. ► The observed increase in magnetic parameter Mr with Nb5+ doping reflects the corresponding increase in the suppression of spin spiral with a continual change in lattice parameters and different exchange pathways owing to the distortion created by Nb5+ doping, changing the statistical distribution of Fe3+/Fe2+ as a result of charge compensation. ► The increase in absolute value of magnetocapacitance with increasing magnetic field, BiFe1−xNbxO3 is expected to show magnetoelectric coupling below Neel temperature. - Abstract: Polycrystalline BiFe1−xNbxO3 ceramics have been synthesized by standard solid-state reaction method. The effect of Nb substitution on the dielectric, magnetic and magnetoelectric properties of the BiFeO3 multiferroic perovskite was studied. X-ray diffraction pattern revealed that all the samples with x = 0.00–0.10 showed rhombohedral perovskite structure. We obtained single phase upto doping concentration of x = 0.05 and with further increase in Nb concentration, some impurity peaks appeared. An anomaly in the dielectric constant (ε) and dielectric loss (tan (δ)) in the vicinity of the antiferromagnetic Néel temperature (TN) was observed. Nb substitution reduced the antiferromagnetic Néel temperature (TN) in BiFe1−xNbxO3. Proper amount of Nb could decrease the dielectric loss. Magnetic hysteresis loops measured at 5 K/300 K and temperature dependent magnetization curves indicated ferromagnetism in Nb substituted BiFeO3 ceramics. The room temperature magnetic moment was found to increase with increase in Nb concentration. The dependence of dielectric constant on the magnetic field is an evidence of magnetoelectric coupling in BiFe1−xNbxO3 ceramics.