Studies On Preparation Of Rare Earth Doped Co₂Y Type Barium Ferrite Powders By The Coprecipitation Method And Rheological Phase

Ferrite is a composite oxide material by composition of one or more metal elements and iron group elements. It is a class of ferromagnetic and wave absorbing metal oxide materials. In this thesis, the studied ferrite belongs to magnetoplumbite Y-type（Co₂Y） barium ferrite, has a hexagonal crystal structure, and shows ferromagnetic potent.In this thesis,two methods, co-precipitation method and rheological phase method, were used to prepare barium ferrite Ba₂Co₂Fe₁₂O₂₂, respectively. Combined with X-ray diffraction（XRD）analysis, differential scanning calorimetry（DSC） analysis and scanning electron microscope（SEM） analysis, the factors, such as precipitation dosage, p H value, reaction temperature, reaction time, calcination temperature, calcination time and heating rate, were investigated to confirm the optimum process conditions.On this basis,La3 + and Eu3 +were doped into Co₂ Y barium ferrite. The product phase, morphology and other aspects were studied when the La3 + and Eu3 + ions were doped with different amounts.The results showed that: when the barium ferrite Ba₂Co₂Fe₁₂O₂₂ was prepared by the co-precipitation method, the optimum process conditions were as follows.（1） The p H value of precipitantion solution was 9.（2） The calcination temperature was 1100 ℃.（3）The calcination time was 5 h.（4） The heating rate was 8 ℃/min.The Co₂ Y barium ferrites were doped with La³⁺ and Eu³⁺, when replacing the Ba₂+, the maximum amount of doped La³⁺ and Eu³⁺ were both x=0.25. When replacing the Fe³⁺, the maximum amount of doped La³⁺ and Eu³⁺ were both x=0.30.When the barium ferrite Ba₂Co₂Fe₁₂O₂₂ was prepared by rheological phase method, the optimum process of reaction conditions were as follows.（1） The ratio of the theoretical amount precipitation dosage to the actual amount precipitation dosage was 1.5 to 1;（2）The reaction temperature was 120 ℃;（3）The reaction time was 12 h;（4） The calcination temperature was 1100 ℃.（5）The calcination time was 5h.（6） The heating rate was 8 ℃/min.The Co₂ Y barium ferrites were doped with La³⁺ and Eu³⁺, when replacing the Ba₂+, the maximum amount of doped La³⁺ and Eu³⁺ were both x=0.25. When replacing the Fe³⁺, the maximum amount of doped La³⁺ and Eu³⁺ were both x=0.30.