Preparation And Magnetic Properties Of Ion-substituted SrFe₁₂O₁₉ Ferrite

Because of its high coercivity,fine chemical stability and high cost performance,M-type magnetic magnetoplumbite ferrite SrFe₁₂O₁₉?SrM?has become a widely used permanent magnet ferrite material.In order to further improve its magnetic properties,the preparation and ion substitution are still paid much attention by many researchers.In this thesis,the egg white was used as the metal ion complex to prepare SrM ferrite via a sol-gel method,and the topography,phase composition and magnetic properties were studied.For the La³⁺-substituted specimens with a nominal composition Sr_1-xLa_xFe₁₂O₁₉?x=0.01,0.02,0.03 and 0.04?,it was found that when the atomic ratio Sr/Fe is 1:8,the SrM ferrites can form a single-phase structure at a sintering temperature of 1215oC,1250oC or 1300oC.The particle size of the sample grew as the sintering temperature increases.It was also found that when the sintering temperature was 1300oC and x=0.04,the coercivity reached the maximum of 94.40 kA/m.In general,the specimen with x=0.04 presented the best magnetic properties.For the La-Ce co-substituted Sr_1-2xLa_xCe_xFe₁₂O₁₉?x=0.00,0.01,0.02 and 0.03?specimens,it was found that with the same La-Ce content,the H_cj and the saturation magnetization of specimens with a sintering temperature of 1215oC is higher than that of 1250oC.When x is 0.02,the specimens presented the best magnetic properties.For the Ce-subsitituted SrCe_xFe_12-xO₁₉?x=0.00,0.02,0.04,0.06,0.08?specimens,the best magnetic properties were obtained at x=0.04 and a sintering tempareture of 1215oC,in which the coercivity increased from 123.14 kA/m?x=0.00?to 129.46 kA/m accompanied with almost the same saturation magnetization.It was found that when x=0.04,1215oC,1250oC,1300oC sintering temperatures.The integrated magnetism of 1215oC is the best.