Preparation And Magnetic Properties Of Controllable Morphology Nano-Permanent Magnetic Ferrite With Soft Chemistry Method

In the paper, the development history and typical preparation method of permanent magnetic ferrite material were introduced. The factors (optimistic mol ratio of Fe3+ to precursor, pH, water volume and so on) to obtain fine and dispersing homogeneously permanent magnetic ferrite particles were determined. At the base of craft, co-completion method and inorganic salt were used to prepare controllable morphology nano-SrFe₁₂O₁₉.The mechanism was analyzed. The craft was optimized to improve the magnetic properties of various morphologies.SrFe₁₂O₁₉ was doped, cross coupled withα-Fe2O3 orγ-Fe2O3.The influence of doping and cross coupling to magnetic properties were studied.(1)The water volume, pH value, the mol ratio of citric acid to metal ion, calcination temperature was determined to prepare pure fine well-dispersed nano-SrFe₁₂O₁₉ with citric acid method. The optimum craft was as follow: the molar ratio of citric acid to metal ion was 1:1,the pH value was 6,the volume of water was 120 ml, calcinated 900℃at 2 h.(2)As the optimum preparation craft, ethanedioic acid,stearic acid and EDTA were used as co-complex agent to obtain spherical,spindle,rod-like,needle-like nano-SrFe₁₂O₁₉ respectively. The influence of co-complex agent to the morphology, diameter, dispersion character, magnetic properties of SrFe₁₂O₁₉ was studied. The result indicated that the coercivity of needle-like samples was maximum, the coercivity of rod-like samples spindle samples spherical samples decreased gradually.(3)At the base of preparation of nano- SrFe₁₂O₁₉, KCl,KBr and KI were added in the calcination process to prepare needle-like,rod-like and bubble nano-SrFe₁₂O₁₉ respectively. The optimum quantity of KCl,KBr and KI was determined. The influence of inorganic salt to the morphology, diameter, dispersion character, magnetic properties of SrFe₁₂O₁₉ was studied.(4)The SrFe₁₂O₁₉ were doped at the base of EDTA-citric acid co-complex method. The influence of the doped agent to the magnetic properties of SrFe₁₂O₁₉ was studied. The coercivity, saturation magnetization and remanent magnetization of prepared samples were 6052.5 Oe,71.8 emu·g-1and 42.5 emu·g-1 respectively.(5)α-Fe2O3 orγ-Fe2O3 was recombined with SrFe₁₂O₁₉,the change mechanism of M-ferrite was analyzed. The coercivity, saturation magnetization and remanent magnetizationγ-Fe2O3/ SrFe₁₂O₁₉ Sr-M style ferrite composite were6198.3 Oe,71.5 emu·g-1 and 42.3 emu·g-1 respectively. The comprehensive magnetic properties of samples was improved.