Effect of Li-Nb Codoping on Structural, Dielectric, Optical, and Multiferroic Properties of BiFeO3

Abstract

(Bi1−xLix)(Fe1−xNbx)O3 (x = 0, 0.1, 0.2, 0.3, 0.4) (BLFN) ceramics have been synthesized by a standard solid-state reaction method and the effect of Li-Nb codoping on their structural, dielectric, optical, and multiferroic properties investigated using various experimental techniques. X-ray diffraction study indicated the formation of pure rhombohedral phase for x = 0 and 0.1. However, a structural phase transition from rhombohedral to tetragonal phase was observed for the x = 0.3 and 0.4 compositions, with a mixed phase for x = 0.2. An enhancement of the dielectric constant (except for x = 0.4) was observed, with a reduction in the tangent loss. A decrease in the leakage current density by four orders of magnitude along with a reduction of the grain size were observed for the sample with x = 0.1. With increasing Li-Nb concentration in bismuth ferrite, significant improvements in remanent polarization, soft ferromagnetic/ferrimagnetic characteristics, and magnetoelectric coupling coefficient were observed. The Fourier-transform infrared (FTIR) peak at 555 cm−1 for x = 0 gradually shifted towards higher wavenumber with increasing Li-Nb concentration.