Effects of La3+-Zn2+ doping on the structure, magnetic, electrical, and dielectric properties of low temperature sintered Sr-hexaferrites

The Sr-1 xLaxFe12 xZnxO19(x= 0-0.3) hexaferrites with Bi2O3 additive were prepared by microwave sintering method at low sintering temperatures, and their crystal structure, microstructure, magnetic, electrical, and dielectric properties were studied. The results show that the pure M-type phase is obtained for the ferrites with x <= 0.2. With x further increasing to 0.3, the multiphase structure is inevitably formed, where the LaFeO3 phase coexists with the M-type phase. In the single phase region, the varied magnetic, electrical, and dielectric properties with La3+-Zn2+ doping amount are well explained by the occupancy effects of La3+ and Zn2+ in magnetoplumbite structure. It is suggested that the Zn2+ ions replace the Fe3+ ions at 4f(1) site with x <= 0.15, but the substitution of Zn2+ for Fe3+ occurs at 2b site preferentially when the La3+- Zn2+ doping amount exceeds 0.15.