Crystal structure and magnetism of BiFeO3 nanoparticles regulated by rare-earth Tb substitution

Tb-doped BiFeO 3 nanoparticles were prepared using sol–gel method. The effect of Tb substitution on crystal structure and magnetism of BiFeO 3 nanoparticles were investigated. It is shown that the crystal structure and magnetism of BiFeO 3 nanoparticles are regulated by rare-earth Tb substitution. Particularly, the sizes of the particles are reduced to smaller than 100 nm after doping with Tb. The magnetization of Tb-doped BiFeO 3 nanoparticles has been enhanced in magnitude, which is mainly attributed to the suppression of spin cycloid structure belonging to R3c phase fraction in the process of rhombohedral-to-orthorhombic structural phase transformations. At the meantime, the magnetic hysteresis loops show exchange bias towards negative axis. The exchange bias behaviors originate from the coupling interaction between antiferromagnetic core and ferromagnetic surface. The present work provides a route regulating the magnetization of BiFeO 3 particles as well as further promoting its applications in multiferroic materials.