Crystal Structure and Spontaneous Magnetism of BiFeO3 Powder Synthesized by Hydrothermal Method

Abstract

Single-phase BiFeO(3) powder was successively synthesized by a low-temperature hydrothermal method. Scanning electron microscopy and transmission electron microscopy results showed that BiFeO(3) powder had several hundred nanometers to micrometer-sized particles with a broad size distribution. BiFeO(3) powder showed weak-ferromagnetic behavior with a small magnetization value (M(s) similar to 20 memu/g) at room temperature. Rietveld refinement results for the crystal structure show the displacive disorder of the Fe-site(6a); the Fe-site(6a) splits into two pairs, Fe(1) and Fe(2) displaced by 0.9 angstrom from each other and these sites are partially occupied. Hence the O-site(18b) also splits into the two partially occupied sites forming a distorted FeO(6) octahedras. The weak ferromagnetism observed in the hydrothermal BFO powder is ascribed to the displacive disorder of FeO(6) octahedras resulting in an incomplete counterbalance between the antiferromagnetic sublattices of the Fe-ions.