The study of local atomic and electronic structure with magnetic properties of Bi(Fe0.95Co0.05)O3 ceramics

The origin of the room-temperature ferromagnetism of Bi(Fe1−xCox)O3 (x=0, 0.05) has been investigated by X-ray Absorption Fine Structure (XAFS) and Soft X-ray Absorption Spectroscopy (SXAS). The results of XAFS data indicate that partial Fe cations occupy Bi-sites of lattices and the dopant Co cations occupy Fe-sites. The existence of divalent Fe2+ ions in this system is detected. The O1s core level SXAS spectra indicate the crystal field split energy for x=0.05 sample is larger than that for x=0 sample, which means a structural distortion. The origin of ferromagnetism in both samples is related to the existence of Fe2+ ions, crystal lattice distortion and occupation of Fe ions. To the enhancement of saturated magnetizations in the Co-doped sample, the existence of Fe2+ ions is not the dominant factor, while the crystal lattice distortion due to partial Fe ions occupying at Bi-sites plays an important role.

► Enhanced magnetization (MS=1.6 emu/g) in Co-doped BiFeO3 is observed.
► XAFS results show that partial Fe ions occupy Bi-sites of BiFeO3 and Co ions occupy Fe-sites.
► The ratio (fitted by XAFS) of Fe ions at Bi site to the whole Fe ions is about 9.4%.
► The existence of divalent Fe2+ ions and the structural distortion are demonstrated.
► Partial Fe ions at Bi site and lattice distortion are the possible main reasons of enhanced MS.