Studies On The Structure And Magnetic Properties Of Substituted Sr Hexaferrite Nanoparticles

Magnetic recording is one of the most important recording technologies. Developing new type of magnetic recording media is most important for the recording density of magnetic recording to keep its speed of increasing. Recently, magnetoplumbite hexagonal ferrites have been considered as attractive candidates for high-density recording materials because of the good mechanic, chemical properties and high magnetic anisotropy.In this thesis, LaZn, Cr, ZnTi and ZnIr doped Strontium ferrite nanoparticles were prepared by chemical sol-gel route. The samples were characterized by x-ray diffractometry(XRD) and vibrating sample magnetometry (VSM). We discussed the structure and magnetic properties of the samples. The main results were as follows:The results of phase transition of Sro.7Lao.3Fen.7Zno.3O19 indicated that r-Fe2O3 phase was formed before strontium hexaferrite phase. The samples showed nearly soft magnetic behavior below annealing temperature 650C. a-Fe2O3 phase is very harmful to magnetic capability during the formation process.The samples were single phase at the annealing temperature 900C.The experimental results showed that saturation magnetization os of Sr1-xLaxFe12-xZnxO19(x=0~0.5) increased at the beginning and then decreased slowly, while the coercive strength Hc decreased monotonously with increasing x. For SrFe12-xCrxO19(x=0-1.0), When the substituted amount x was below 0.4, the samples were the single M-type hexagonal ferrite, and when the substituted amount x was 0.2, the saturation magnetization crs attained the maximum.The Magnetic properties of SrFe12-2x(ZnTi)xO19(x=0~1.0)and SrFe12-2x(ZnIr)xO19 (x=0~0.6) were discussed. For an amount of substitution 0