Effect of La and Ni substitution on structure, dielectric and ferroelectric properties of BiFeO3 ceramics

In this communication, we present the results on Bi1−xLaxFe1−yNiyO3 (x=0.0, 0.1; y=0.0, 0.05) samples processed by solid-state reaction route in order to study crystalline and electronic structure, dielectric and ferroelectric properties. The best refinement was achieved by choosing rhombohedral structure (R3c) for BiFeO3 and Bi0.9La0.1FeO3 samples. Whereas, the XRD pattern of BiFe0.95Ni0.05O3 and Bi0.9La0.1Fe0.95Ni0.05O3 samples were refined by choosing rhombohedral (R3c) and cubic (I23) structure. Raman scattering measurement infers nine Raman active phonon modes for all the as prepared samples. The substitution of Ni ion at Fe-site in BiFeO3 essentially changes the modes position i.e. all the modes are observed to shift to lower wave number. Dielectric constant (ε′) and dielectric loss (tan δ) as a function of frequency have been investigated and they decreases with increasing frequency of the applied alternating field and become constant at high frequencies. This feature is a characteristic of Maxwell Wagner type of interfacial polarization. The remnant polarization (Pr) for Bi0.9La0.1FeO3, BiFe0.95Ni0.05O3, and Bi0.9La0.1Fe0.95Ni0.05O3 are 0.08, 0.11, 0.69 μC/cm2, respectively and the value of coercive field for Bi0.9La0.1FeO3, BiFe0.95Ni0.05O3, and Bi0.9La0.1Fe0.95Ni0.05O3 are 0.53, 0.67, 0.68 kV/cm, respectively. X-ray absorption spectroscopy (XAS) experiments at Fe L2,3 and O K-edges are performed to investigate the electronic structure of well-characterized Bi1−xLaxFe1−yNiyO3 (x=0.0, 0.1; y=0.0, 0.05) samples. The presence of reasonable ferroelectric polarization at room temperature in Bi0.9La0.1Fe0.95Ni0.05O3 ceramics makes it suitable for technological applications.