Improved dielectric and ferroelectric properties of dual-site substituted rhombohedral structured BiFeO3 multiferroics

We report a comparative study of structural and electrical properties by dual-site rare-earth ions substitution in BiFeO3 (BFO) crystal. BiFeO3 (BFO), Bi0.9La0.1FeO3 (BLFO), BiFe0.95Ni0.05O3 (BFNO), and Bi0.9La0.1Fe0.95Ni0.05O3 (BLFNO) samples were prepared by solid-state reaction route. X-ray diffraction patterns reveal that samples have rhombohedral structure (R3c symmetry). Raman scattering measurement infers nine Raman active phonon modes. The substitution of Ni ion at Fe-site in BiFeO3 essentially changes the modes position i.e. all the modes are observed to shift at lower wave number. Frequency variation of the dielectric constant (epsilon') and dielectric loss (tan delta) has been investigated. Both decrease with increasing frequency of the applied alternating field and become constant at high frequencies signifies substantial role of interfacial polarization. From ferroelectric loop, remnant polarization and coercive field enhancement is observed, indicating that dual-site substitution is an effective method to modify BFO material. (C) 2016 Elsevier B.V. All rights reserved.