Effect of chromium substitution on structure and magnetic properties of Bi2Fe4O9

Orthorhombic Bi2Fe4−xCrxO9 (x=0.0, 0.25, and 0.75) nanoplatelets were synthesized by a simple hydrothermal method. The structure, morphology, and magnetic properties of the obtained powders have been characterized. Calculation of the lattice parameters of Bi2Fe4−xCrxO9, as well as bond lengths and angles, was carried out by X-ray diffraction Rietveld refinement. The volumes of the metal–oxygen tetrahedra and octahedra were calculated to be sequentially increasing as the Cr doping level increases. The samples undergo an antiferromagnetic transition at 250±5K. The magnetic moments of the samples increase with higher Cr doping level. The 3d electron spin state for Fe3+ in the as-prepared samples is different, which is possibly due to the distortion of Fe–O tetrahedra and octahedra in the crystal structure after chromium substitution.