Effects of Oxidizing/Reducing Agent Ratio on Phase Purity, Crystallinity, and Magnetic Behavior of...

Fabrication of phase-pure well-crystalline BiFeO₃ submicroparticles in large scale is of great importance for the utilization of this rhombohedrally distorted perovskite material in applications such as memory storage and spintronic devices and visible photocatalyst for the degradation of organic pollutants. In fact, because of the narrow temperature range of phase stabilization, the fabrication of phase-pure BiFeO₃ in large scale remained elusive. We present the synthesis of phase-pure BiFeO₃ particles of submicrometric dimensions (246-330 nm average size) through the adjustment of oxidizing/reducing agent ratio in solution combustion process utilizing glycine as reducing agent and nitrate precursors as oxidizing agent. Utilizing X-ray diffraction and Raman spectroscopy, we demonstrate that the BiFeO₃ submicroparticles synthesized at equivalence ratio (Φ_e) close to 0.5 do not contain undesired impurities such as Bi₂Fe₄O₉ and Bi₂₄Fe₂O₃₉. Moreover, the submicroparticles are highly crystalline, possessing high room temperature magnetic moment and stable antiferromagnetic behavior across a wide temperature range. The superparamagnetic behavior at low magnetic field manifested by impurities attached to the BiFeO₃ submicroparticles might lead to their use as effective magnetically separable photocatalysts.