Antiferromagnetic-ferromagnetic transition in Bi-doped LaFeO3 nanocrystalline ceramics

A series of nanocrystalline La1-xBixFeO3 (0.0≤x ≤ 0.5) ceramic powders were successfully prepared by the sol-gel method. X-ray diffraction and transmission electron microscopy were used to investigate the crystal structure evolution and hyperfine interactions of the samples. The average diameter of the powders was revealed to be approximately 80 nm. All the samples were crystallized into an orthorhombic crystal structure (space group Pnma) with no second phase. The magnetization of the Bi-doped samples obviously improved with increasing Bi content. A remarkable antiferromagnetic/ferromagnetic transition was detected at x ≥ 0.2, and a high coercive field of 23.05 kÖe was obtained with x = 0.5. The high correlation between the magnetization parameters and bonding characteristics indicated that significant stretching of the Fe3+-Od2- bonds and a decrease in Fe3+-Od2--Fe3+ linkage angles were the main origins of the strong ferromagnetism in the Bi-doped systems.