Effects of Zr⁴⁺ doping on structure, magnetic and optical properties of Bi₂Fe₄O₉ powders

A series of Bi₂Fe_{4 (1−x)} Zr_4xO₉ (x = 0, 0.03, 0.05 and 0.08) powders have been synthesized successfully by the low heating temperature solid-state chemical reaction to investigate the effects of Zr⁴⁺ doping on structure, morphology, magnetic and optical properties. X-ray diffraction (XRD) and Raman spectroscopy studies reveal the single-phase Bi₂Fe₄O₉ orthorhombic structure without impurities and lattice structural distortion in Zr⁴⁺ doped powders. The morphology, particle size and chemical compositions of powders, characterized by Field Emission Scanning Electron Microscope (FE-SEM) equipped with energy dispersive X-ray spectroscopy (EDS), show the well-developed cubic grains appearance. Magnetic and optical characteristics are observed to depend strongly on the concentration of Zr⁴⁺ ions in the powders. An induced weak ferromagnetism along with improved magnetization at room temperature is observed. The improved magnetization and the reduced bandgap with the increase of Zr⁴⁺ concentration are discussed in terms of the variation of structure and microstructure due to the Zr⁴⁺ doping effects.