Influence of doping concentration on room-temperature ferromagnetism for Fe-doped BaTiO3 ceramics

Ba(Ti1-xFex)O3 ceramics (x=7, 30 and 70 at%) were prepared by solid-state reaction. All samples are single-phase with 6H-BaTiO3-type hexagonal perovskite structure. Moessbauer spectra show all Fe atoms to be present as Fe3+ in BaTiO3 lattice, occupying M1 octahedral and pentahedral sites. Room-temperature ferromagnetism is exhibited and saturation magnetization gradually decreases with increasing Fe content. The observed ferromagnetism is considered to be an intrinsic property of Ba(Ti1-xFex)O3, originating from super-exchange interactions between Fe3+ in different occupational sites associated with oxygen vacancies. The variation in magnetization with Fe content is related to the ratio of pentahedral to octahedral sites and oxygen vacancies