Influence of Eu substitution on structural, magnetic, optical and dielectric properties of BiFeO3 multiferroic ceramics

Eu substituted BiFeO3 (Bi1−xEuxFeO3; x=0–0.15) polycrystalline ceramics were synthesized by a solid state reaction method. Rietveld refinement of X-ray diffraction patterns reveals that samples crystallize in R3c structure for x≤0.10 and (R3c+Pn21a) phases coexist for x≥0.12–0.15. The magnetic measurements show weak ferromagnetic nature of Eu substituted BiFeO3 samples due to ferromagnetic coupling between Eu3+ and Fe3+ ions. The remnant magnetization is found to increase from 0.0003 emu/g for x=0.00 to 0.087 emu/g for x=0.15. The gradual change in line shape of electron spin resonance spectra has been attributed to local distortion induced by Eu substitution. UV–visible absorption spectra in the spectral range 1.12–3.5 eV were dominated by two charge transfer transitions and two doubly degenerate d–d transitions. The optical band gap is found to decrease from 2.25 to 2.16 eV with increasing Eu concentration. Improved dielectric properties with enhancement in frequency independent region of dielectric constant and loss have been observed.