Lanthanum modified BFO–BT solid solutions: a structural, electrical and magnetic study

In this paper, structural, electrical and magnetic characteristics of Lanthanum-modified multiple perovskite BiFeO₃–BaTiO₃(BFO–BT) solid solutions have been reported. Detailed structural analysis via Rietveld refinement technique using X-ray diffraction pattern provides the evolution of a mono-phase distorted perovskite structure with the concurrence of rhombohedral structure. Scanning electron micrograph of La modified BFO–BT solid solutions at ambient temperature exhibits that with varying La content in the material, more symmetric structure, high density and uniform grain distribution are obtained. The dielectric parameters are strongly depends on composition, frequency and temperature. The well defined polarization–electric field hysteresis loop of the samples at room temperature suggests that La substitution at the Bi site of the solid solutions strongly affects remnant and saturated polarization of the materials. The low lanthanum concentration in the solid solutions is able to provide a well-defined ferromagnetic characteristic with saturation magnetization (M_s) in the range of 6–9 emu/g and remnant magnetization(M_r) 1.5–2 emu/g and shows that BT substitution in BFO releases latent magnetization whereas addition of higher content of barium titanate shows an anti-ferromagnetic behaviour which has been confirmed by M-H hysteresis loop and Arrot plots. Based on the derived parameters of La modified solid solution, it is expected to fabricate a multifunctional device.