Influence of Y doping on structural, vibrational, optical and magnetic properties of BiFeO 3 ceramics prepared by Mechanical Activation

Abstract Y substituted BiFeO 3 (Bi 1−x Y x FeO 3; x=0.0–0.1) polycrystalline ceramics were synthesized by Mechanical Activation. The effect of varying composition of Y substitution on the structural, vibrational, optical and magnetic properties of doped BiFeO 3 (BFO) ceramics has been investigated. Rietveld refinement of X-ray diffraction patterns reveals that all samples crystallize in distorted rhombohedral structure with R 3 c symmetry and no structural transition has been observed. Raman spectroscopy also confirmed the distorted perovskite structure with R 3 c space group. Optical studies in the spectral range 1–4.5 eV were dominated by two d-d and three charge transfer (C-T) transitions. The optical band gap decreases from 2.11 to 2.01 eV with increasing Y substitution. Room temperature magnetic measurements showed weak ferromagnetic ordering and enhancement in magnetization with increasing Y concentration. Mechanical activation leads to significantly altered magnetic properties, particularly in higher Y-doping samples. The Mossbauer spectra demonstrate the suppression of spiral spin modulation of the magnetic moments resulting in enhanced ferromagnetism with increasing doping concentration. Significant increase in Neel temperature T N in the substituted compounds was discussed on the basis of structural distortions.