Enhanced ferromagnetism and microwave absorption properties of BiFeO3 nanocrystals with Ho substitution

Ho doped BiFeO3 nanoparticles were synthesized by a sot-gel method, and their magnetic and microwave absorption properties were investigated. X-ray diffraction pattern shows that Ho ions occupy the Bi site in BiFeO3. The Ho substitution is found to enhance ferromagnetic properties, which attributed to the destruction of spin cycloid structure and the emergence of exchange interaction between Ho 4f electrons and Fe 3d electrons. Microwave magnetic loss also shows an obvious increase in the range of 2-18 GHz for high level substitution, caused mainly by the natural ferromagnetic resonance at microwave frequencies. Furthermore, microwave absorbing bandwidth and intensity are greatly improved due to the better electromagnetic match property of BiFeO3 with Ho substitution. (C) 2012 Elsevier B.V. All rights reserved.