Improved structural, dielectric and magnetic properties of Ca2+ and Nb5+ co-substituted BiFeO3 multiferroics

Ca2+ and Nb5+ co-doped multiferroics having composition Bi0.8Ca0.2Fe1−xNbxO3 (x = 0.00, 0.05, 0.07, and 0.10) were synthesized via solid-state reaction method. Effect of substitution was analyzed by structural, electrical and magnetic measurements of modified BiFeO3 multiferroics. The samples were characterized by X-ray diffraction (XRD), and results support that impurity phases, which normally occurred in BFO, were significantly diminished in modified BiFeO3. Rietveld refinement of XRD patterns demonstrates that phase transformation occurred in all prepared samples. Structure symmetry gets disturbed in presence of Nb and mixed phase (rhombohedral (R3c space group) and orthorhombic phase (Pbnm space group)) was confirmed by refinement. The studies of dielectric, impedance and electrical properties at a wide range of temperature and frequency offered us noticeable information of Nb substitution. Frequency dependence impedance confirms the non-Debye type of relaxation. Nb doping increases resistivity and samples show polarization hysteresis loop. All samples show ferromagnetism in modified multiferroics with maximum remanent magnetization is Mr = 0.0581 emu g−1 and coercive field is Hc = 4.7505 kOe for x = 0.10 which is ten times of magnetization observed in parent sample. Co-substitution at A and B site is responsible for phase transformation and enhancing electrical and magnetic properties.